texts: FreeRtos problems in ADC task and Streaming Task

texts:
I have an ADC task that uses 4 channels and uses the DMA for transfer.
I also have a streaming client which streams the ADC data through the TCP socket.
I made the ADS Task lower priority than the streaming client.

I'm sending an integer that selects which ADC channel is selected as a message queue to the streaming client.

The problem is I get queue overflow when sending that adc channel integer.

ADC TASK

  if(bufferSelect != BUFFERS_NOT_READY)
        {
            if(xQueueSend(g_adcQueue, &bufferSelect,  0) != pdPASS)
            {
                throwError(ERROR_MESSAGE_QUEUE_FULL);
                PRINTF("%s\r\n", getErrorMessage(ERROR_MESSAGE_QUEUE_FULL));
            }
            bufferSelect = BUFFERS_NOT_READY;
        }

Streaming client task

/* obtain next buffer ready event */
        if(xQueueReceive(g_adcQueue, &bufferSelect, 0) == pdFALSE)
        {
            g_stopStreaming = true;
            continue;
        }


texts: How close is too close for traces on a PCB?

texts:
Are these traces too close for conventional PCB manufacture? DRC check advises against it, but I haven't filled out all the settings for it.

For scale, the resistors are all 0603.


texts: simple battery back-up power path design idea

texts:
I need an application with back-up battery. Like UPS when power go down device will work with battery. There are chips with power path option but it is diffucult me to get components from outisde of my country (not impossible but diffucult and expensive so i stick components can be found here) and the one i got bq24072 it is very diffuclt to solder. So i came up with below idea with mcp73831 but i am not sure it will work. I will try it with dead-bug prototyping after i get opinions (i am afraid of blowing battery on my face). I am planning to use Li-Po battery

MOSFET's gates can be driven with transistors. The battery symbol is only for showing where the battery is. Will that work or can anyone suggest better solution. or i shoul stick with a chip which has power-path feature?


texts:
the circuit below is a triangular and square wave generator.
With the first stage (the integrator) I can generate a triangular wave, and with the second stage (comparator) I can generate a triangular wave with a limited amplitude.

I've never seen this circuit with the net circled in red. What does this net does?

The text of the exercise says: Analyze the circuit assuming ideal op-amps.
...the circuit is an astable multivibrator in which zener diodes are ideal with Von =0,6V and Vbkd = 5.6V.
1)Describe the circuit and what kind of waveform can be found at Vout and Vs
2) find R1 and R2 in order to obtain an amplitude  of Vout of Vpeak = 10V, and f = 10kHz.


texts:
I'm new to this forum. I have a TA-1630 that is truly baffling me. I know that some of you have had experience of this amplifier or a similar model, and wondering if you can offer some experience/advice.

This amplifier has a volatile output section, in that it likes to blow the transistors to oblivion. The result if the transistor stays intact is the one of the output pair shorted sending around 29v out the speaker terminals. The other one goes OC.

I have pulled the 2 previous stages and diode tested all of them. All other transistors seem fine. I changed a couple of suspect resistors and the capacitors of the bad channel. I have changed the bias diodes to the Sony suggested rubber diode and that made little change - it worked with new output pairs of TIP41/2C as suggested in the ST transistor cross reference list. It worked until I turned up the volume. The same channel exploded again.

I checked everything I could find, traced PCB tracks for bridges or breaks. Checked the rubber diode, checked the bias pot, though I see the rubber diode overrides that. Rechecked the transistors. Reflowed solder joints. Changed the output ones again. Double double checked, power on - bang.

Checking component values from left to right, all seem to read the same.

With this PCB, it is almost impossible to work on it in situ. Testing is a nightmare, as the solder side of the PCB is inaccessible when you come to power on. Every time I have to change something, it's weakening the heatsink screws, the aged PCB tracks, the hardwired cables. I have a virtual scope (usb) and a multimeter. I cannot get the thing to be stable enough to test via the scope.

I have no way of running this on low power to reduce chance of blowing up yet more parts, no way of easily testing it minus the output Transistors. I do not want to apply power to it with the PCB sticking out of the chassis, nor undo perfectly good original wiring to the preamp. What I wanted to do is simply replace the dud parts and move happily on, how wrong I was.

Anyone had a similar issue? I realise many did with the SV04F, but mine is not that straightforward. I just cannot see what is causing this. Could the driver stage be faulty even though they read fine on a diode check?

I had another Sony that was "fun" to fix - TA-F30. That one though didn't explode transistors, it just had a tendency to overheat and fluctuate the bias. That was down to the diodes. Fixed that.

Update:
I've had another tour round the PCB, referring to the service manual. I then noticed that in the parts list of the manual, the transistors differed from those on the Schematic! Also, someone had repaired this unit in the past and for some reason, replaced the drivers with smallish signal 0.75w transistors. The proper drivers were sitting where small signal transistors should be, constant current and pre-driver. In the schematic, the same pair 5w driver transistors are also listed in the position of constant current Q1/206 and pre-driver Q1/207.  I also believed it must be correct until yesterday I noticed the parts list have different transistors specified for them. I cannot get the required transistors, and those subs for the drivers didn't spec close enough, so I swapped the drivers to the correct positions and subbed the missing small transistors with pairs of A733 and C945 which are close enough. I don't have the replacement power transistors, but running the amp on the 1 good channel with reduced power as suggested resulted in the good channel actually working better, louder as one would expect. It didn't blow up even with the incorrect drivers where as the other channel did, but let's see if my correction of the circuit would make a difference.


texts:
I am building an invention (WIPO Patent W02020172689) to control the pitch of a fan/propeller/turbine blade that uses a thread applied to the rotating system and a nut threadedly mated to that rotating system; the nut has radial protrusions and is made out of a ferromagnetic material -- it is spun using electromagnets which are switched off and on using the logic levels of a gear tooth sensor disposed near the threaded nut's radial protrusions.  I need to position two gear teeth sensors at angles in relation to the electromagnets so that I can create logic levels that will turn off and on when I can maximizing the reluctance torque.
I have read through journal articles looking for a torque vs angle plot to help guide this decision.  I believe the terminology for this is the "load angle."  This paper displays this plot:

Is it a correct inference to say that torque is maximized when the rotor pole's angle in relation to the stator pole is maximized for a 6/4 configuration when "this" angle is between 10 and 25 degrees?


texts: Ideal method for handling multiple VDDs in a system

texts:
I am trying to "glue" a bunch of existing components together and it's turning into a power supply nightmare.  I am trying to determine the best way to generate relative voltages for all of the different components around a common ground.

In the previous version of this hardware, a transformer existed with a bunch of taps were used with isolated supplies.  I am adding a MCU that will have an optoisolator to the USB so that it is not "yanked" anywhere.   I have a good ground that exists, but that's about my only saving grace.  The overview of the system follows.

I have an ADC input that will have the "common gnd" about 1/2 way up the range.  The ADC that was previously used was the standard SAR with 5V rails and the ADC had 3.3v tolerant inputs.  The MCU runs at 3.3V and just doles out SPI commands.  +-11V exist for an amplifier that I have not included.

The point, I have a real power supply mess, and I feel that I should redesign the system instead of trying to glue it together, but I need a compelling argument outside of complexity.

Does anyone have any experience dealing with an issue where multiple supplies are required?


texts: What type of electric motor drive can be used for keeping a load at specific heights?

texts:
We are planning to adjust the level of a load (around 50 kg) by using an electrical motor. Now we are using a hand crank and we want to get rid of this manual process.

For example we want to implement a control where one can adjust the height of the load. The load is hanging down on a pulley. We want to keep the load at 4 different fixed heights by using an easy push button system or a computer. When one sends signal to the motor the motor will adjust the load to a particular height depending on the signal and then will stop there.

What type of motor and electronic control can be used?


texts: Transformer for electrostatic speaker (high voltage, very low current)

texts:
I've read recently about DIY projects making electrostatic loudspeakers (example). The membrane of the speaker should be supplied with bias DC voltage between 1 and 5 kV, roughly. There is virtually no current needed, only for charging the membrane.

With old CRT screens and photocopiers being short supply, how does one get such a voltage? Around here, only step-down transformers are easily bought, and I don't really want to be using any of those the other way around (effectively putting the rated voltage on the secondary coil).

I can imagine getting nearly 1 kV directly using a 1:1 transformer and voltage quadrupler, but this may prove inadquate. So the question is whether there is another way to get high DC voltage when I can't get my hands on an up-to-spec transformer.

Europe here, so 240V on the tap.


texts:
I want to create a 16x16 LED array in KiCad and I would like to minimize any "manual" work. I can easily copy/paste in schema editor but I would like to align the footprints on PCB in a grid.

I did find these options so far:

Assign the footprints manually. This is the worst case, I will have 512 footprints and even with the use of grids etc, it is a long and error prone work. Not to mention that I may need to do it all again when I decide to change i.e. the grid spacing
Python scripting. This seems like a reasonable way, for example as in KiCAD parametric component placement . But still I will need to make the traces.
Skidl - this seems to be more complicated than scripting inside pcbnew and it even does not allow for footprint placement afaik...
The array tool - this will distribute one component and make copies so I would need to manually redo all references and create traces
Copy/paste - this seems like the most viable method, but I will still need to redo all references.


texts: Signal noise cancelled by touching the leads

texts:
I have a pressure sensor that outputs 0.5V with a +/- 20 mV noise.  I am trying to identify the root cause of the noise using an oscilloscope.
The noise occurs in waves of twice the mains frequency, and each noise wave pulse is made of smaller pulses of much higher fequency.

The noise used to be much higher when I was using a "wall wart" 12V power supply to the sensor than when I used the bench top power supply or a proper 12 V dedicated power supply.

Weird clue 1)  although the noise was partially related to the power supply used, the power output of the wall wart supply didnt show any noise.EDIT: the noise is there, but catching a 50mV noise on a 12V signal was just difficult on my oscilloscope.

Weird clue 2) when I touch with my finger the conductive probes (either positive or negative) of the oscilloscope, while measuring the sensor signal, the noise decreases

I got minor improvement in the noise by putting capacitors between the signal and the ground, but I have a feeling my main issue is elsewhere. Can you please clarify the root cause of the noise ?

Edit: after suggestions, please find the oscillo screen using different power supplies


texts:
So I have an Arduino Uno and I've made a device to humidify my the enclosure for my Tortoise.
The device consists of a temperature and humidity sensor, an LCD screen to display temperature and humidity and a water pump, which comes on if the humidity is below a certain point.

I set the program to loop every ten minutes, so as to not flood the enclosure with too much water but of course that means the LCD screen with only update every ten minutes too.
I want the LCD screen to update every few seconds but the pump to only turn on 10 minutes after it's already been on if the humidity is still too low.

How can I do this?

Here is my code...

#include <dht.h>
#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

dht DHT;

#define DHT11_PIN 7
int pump = 13;

void setup(){
  pinMode(pump, OUTPUT);
  lcd.begin(16, 2);
}

void loop()
{
  int chk = DHT.read11(DHT11_PIN);
  int hum = DHT.humidity;
  lcd.setCursor(0,0);
  lcd.print("Temp: ");
  lcd.print(tmp);
  lcd.print((char)223);
  lcd.print("C");
  lcd.setCursor(0,1);
  lcd.print("Humidity: ");
  lcd.print(hum);
  lcd.print("%");

  if(hum <= 70) {
    digitalWrite(pump, HIGH);
    delay(2000);
    digitalWrite(pump, LOW);
  }
  else{
    digitalWrite(pump, LOW);
  }

  delay(600000);
}

Thanks for your help! =]


texts:
in the schematic on page 5 of this document:

The note says:

  T2a is connected as a diode (clipping diode) to protect the power
  source against higher Vcc voltages.

I assume from this I can replace T2A with a simple diode, with one side connected to pins 4/5 of T2A and the other connected to TRKR (pointing towards TRKR) - am I correct, or have I overlooked something?


texts: Fried microcontroller while taking a voltage measurement?

texts:
Alright, feeling pretty dumb here lol. I was taking a DC voltage measurement with a Fluke 87 V from a pin of a microcontroller to GND, when out came the magic smoke. The pin I was measuring is a 5V output pin. This has happened twice now, I thought the first time my probe may have touched a surrounding pin, but I was extremely careful this time. I've been having trouble with my meter lately - I get erratic readings when trying to zero the leads. Internet search did not yield any results worth speaking of.

I should also say that though this post seems poorly constructed, I'm just looking for obvious issues. I don't want to get into the weeds, just trying to figure out if there's anything that jumps out as an explanation as to why it may have happened.


texts: Making a radio-controlled clock work from a local time signal

texts:
Is it possible to modify radio-controlled clocks (so-called "atomic" clocks, like https://www.amazon.co.uk/Wall-Clocks-Radio-Controlled/s?ie=UTF8&page=1&rh=n%3A376322011%2Cp_n_feature_keywords_browse-bin%3A1249834031) to synchronise to an arbitrary (local) time signal rather than the standard time signal (i.e. MSF in the UK, WWVB in US, or any number of other time signal stations across the world)?

As I see it, this would involve two parts:

a.) Adjusting the radio receiver in the unit to listen on a different radio frequency of a locally-provided time signal rather than the default frequency

b.) Broadcast the desired time signal in the expected format on that frequency.

I've had a look at the signal standard, and I think I'd be able to broadcast a signal as described here http://www.npl.co.uk/upload/pdf/MSF_Time_Date_Code.pdf using a handful of components and an Arduino.
However, I'm not really sure how I'd approach adjusting the receiver as described in a.) - or whether there's a better approach I could take? (or other flaws in my plan I haven't considered), and my Google-fu has not brought up any useful resources to suggest others having achieved this in the past. I wondered whether I'd even need to change the frequency, or whether producing a local signal on the same frequency would have sufficient power to "override" the official time signal?
Any advice would be gratefully received!

To further explain my purpose; I'm not trying to improve the accuracy - I'm trying to broadcast and display an arbitrary local "stopwatch" time, unrelated to whatever the actual current time might be. (From asker's asker's clarifying comment)


texts:
I made a little board using a STM32F205 micro.  For the protos, I just plugged the board into Windows via USB and used STM's DFUSE software to flash the chip with the built in bootloader.  That was fine for protos, but each one takes about a minute and that's too long for doing 1000.

Is there a better way?  Preferably some way to do it without the chip being soldered to the board?


texts: RF trace matching network component pad sizes

texts:
I'm creating an RF connection between a PSoC4 BLE device and the cypress MIFA antenna according to this app note.
I'm confused about the pads that are required by the components used in the RF matching network.  Using a grounded co-planar waveguide with 50 Ohm impedance trace, I've calculated a particular trace width and ground plane separation.
However, when the component pads contact the trace, the pads are a different size than the rest of the trace.  So I suspect there will be an impedance change there, causing reflections and problems.  There are at least 4 such pads along the length of the trace with a pi-filter methodology.
Looking at the PSoC BLE Design files, the pads for the matching network components are sized to match the thickness of the trace precisely.

The manufacturer datasheet for one of the caps used (C14, bridges the gap in the trace, in-line cap Johanson Technology Inc. 500R07S1R5BV4T) does not provide a recommended land pattern.  However, the width of the package is spec'd at 0.02".  This is quite different than the trace width that I currently have calculated (0.012") for my waveguide.
So, to check my thinking:  given that I have a CPWG, that means I can vary both the trace width and the co-planar ground plane clearance to control my impedance.  So should I resolve this difference by setting the trace width to 0.02", and then setting the ground plane clearance to get 50 ohms?  If so, I guess that means I have make sure all of components use the same size pad?


texts: Does the number of batteries help when using a DC 4.5-40V to 5V DC-DC step-down converter?

texts:
I bought for my Raspberry Pi 2 a module which converts a DC input of 4.5-40V To 5V 2A and has an USB output. By connecting two 3.7V Li-ion batteries in series (7.4V) my Raspberry Pi works fine.

I'm curious what happens inside: what happens with the voltage which is cut (in this case 2.4V)?

I'm thinking if connecting more batteries in series would help my Raspberry Pi to live more. Will it?

Does more voltage beyond the 5V limit increase somehow the amperage * hour?


texts: PWM driven bipolar DC motor controller filtered with LC for a peltier element

texts:
I want to control peltier element's temperature with a PWM driven bipolar DC motor controller to be able to switch between heating and cooling and also control the level of it. The peltier element is 12V/8.5A. I also have 12.5A DC power adapter.

I want to buy a motor controller (like this 13A controller) in order to simplify the project as much as possible. This particular controller can be driven by 20kHz PWM.

I was thinking about a following circuit:

in1 and in2 would be connected to outputs of a controller. out1 and out2 would be connected to peltier.

Using 1mH inductors and 470uF gives 232Hz rolloff frequency which is 86 times smaller than 20kHz.

I have a few questions:

1) Does this circuit make sense and is it enough for my situation?
2) I found 1mH 10A inductors, but I'm not sure if I should take into account anything else regarding L and C proportions and this particular circuit
3) Do I have to look for anything specific in capacitor or will any 470uF capacitor be fine? Is bipolar capacitor required?


texts: WD37C65: identify type of floppy disk drive

texts:
This floppy disk controller chip was used in IBM AT compatible machines. It happened that I am currently developing some firmware for it to control FDDs. The circuit and driver are developed and perform properly, the only one thing bothers me:

If I recall back in 90s, IBM PC storage controller BIOS was somehow able to identify the type of drive connected - 1.2M or 1.44M.

The difference must be in supported data rate (when setting up for data transfers), and number of sectors per track (when formatting and accessing media).

Looking to the datasheet of the 37C65 (I use chip SMC37C65C), I can not understand how this identification can be done. There's no status bit showing the number of heads or possible sectors per track; the supported data rate; and performing read command with no diskette will most probably terminate abnormally with invalid C/H/S values (however I did not try).

Anyone has knowledge on the subject?


texts: Understanding the incomplete CMSIS PID motor control documentation

texts: I'm trying to understand the CMSIS PID Motor Control. Obvisouly it is a PID controller in parallel structure (instead of in series stucture or some sophisticated structure). It seems like there is no standardized way of how the "gains" are defined w.r.t. naming as well as valid value ranges. The derived gains A0, A1 and A2 may be calculated from the gains Kp, Ki, Kd. The state array is not documented at all.


texts:
For a Hcs129s12 micro-controller ADC (please see the image) , the  sample-and-hold stage accepts analog signals from the input multiplexer and stores them as a charge on the sample capacitor. The sampling process has two stages:
1. Initially, a sample amplifier (of unity gain) is used to buffer the input analog signal for two cycles to charge the sample capacitor almost to the input potential. This stage reduces charging and discharging the sample capacitor by the signal source.
2. The sample buffer is then disconnected and the input signal is directly connected to the storage node for programmable 2, 4, 8, or 16 cycles.
The conversion time of a sample is given by the following equation:

Conversion time =(no. of bits in resolution + no. of programmed sample clocks + 2)/ ATD clock frequency

I have a question about step 2: when the sample buffer is disconnected and the input signal is directly connected to the storage node for programmable 2, 4, 8, or 16 cycles, does it mean that we store the voltages during the time that the sample buffer is disconnected? If so why we assign a register to this task if we never use this data?


texts:
I'm new to digital communication. How are the terms data rate and sampling rate related to the term "bandwidth" . Am I missing something here?.Can someone explain me in detail?

thanks in advance,
phani tej


texts: Why does carry flag change from 1 to 0 after ADDS?

texts:
While doing my homework on ARM controllers and assembly programming, I stumbled upon a confusing question.
So here's the line of code which I don't understand (there are other codes before and after this line):
ADDS r0, r5, r6

where r5 is 0x20408624 and r6 is 0x42680402.
The question asks me to explain the difference in the carry bit of xPSR before and after executing the ADDS operation.
According to the software I am using, C is 1 before ADDS, and 0 after. I understand why it's 0 after, but why is it 1 before? Could it be related to a previous instruction that has altered C?


texts: Question on uniform semiconductor doping

texts:
So my question is shown above. For sample A , I tried to substitute the value of NA into the
equation for law of mass action , but I was unable to get the answer. I had to use the equation for charge neutrality to get the answer. Why is this so? Shouldn't NA and ND obey the principle of law of mass action as well?

Thanks for the help!


texts: Maximum and Minimum delay of combinational logic circuits

texts:
I am preparing for my exam and I am stuck with this past year question:

In the circuit shown below, the blocks A, B, C, and S are combination logic circuits. FF1 to FF3 are D flip-flops with same timing, i.e. TClk_Q = 0.2ns, Tsetup= 0.5 ns, and Thold = 1 ns. The clock frequency is 100MHz with 50% duty cycle. The clock skew on clock tree network is 0.2ns.

(i) Assume that the worst case delay of the circuit S is 2ns. What is the maximum delay for circuit C?

(ii) Assume that the fastest arrival time of the circuit S is 0.5ns. What is the minimum delay for circuit C?

Any help will be really appreciated. Also some explanation to how your arrived to your answer will be helpful.


texts: Over how many floors can powerline work?

texts:
My girlfriend lives in the same building as a couple of friends of hers. She lives in the 1st floor and the friends live in the 6th floor.

As she doesn't have a telephone line in her room and wants internet, I thought that maybe the friends can share their internet with her. WLAN will not work for that many floors. We cannot add a cable. The only solution I can think of is powerline. I haven't used that and I have only a very vague idea how it works. I guess that there are some elements which would guarantee it not to work; e.g. I have a hard time to imagine that it would work across different buildings.

Could powerline work over that many floors?

It's an older building in Germany; I would guess maybe 14 different apartments.


texts: How many standard deviations is Sensor / Component Uncertainty (+/- X) given in?

texts: For example a resistor of 1kohm with uncertainty of +/- 1%, does this mean in 68% of cases = 1 standard deviation, the resistance will vary by +/- 1%, or does it mean in 95% of cases = 2 standard deviations or is it in 99% of cases = 3 standard deviations the resistance will vary by +/- 1% ?


texts:
In the following question on symmetrical components, the 11kV of the source is the line-to-line voltage. When using symmetrical components you want to be working with line-to-neutral voltage. Am I right in saying this? In the memo for this question the 11kV is devided by squareroot 3 in order to obtain the phase voltages. Initially I used the 11kV without dividing by squareroot 3. How would I determine which path to follow (divide or not by squareroot 3), by looking at this question? Is there a standard which I should always follow, or am I missing key words in the question which tells me exactly what to do?

I am fine with the rest of the question, I'm just confused in determining the phase voltages. Thank you

"A 11 kV source delivers power to a power
system with terminal voltages at rated value.
A fault occurs in the source and it causes the
b-phase voltage Vbn of the source to fall to
zero (not an open circuit). With the a-phase
voltage Van of the source as the zero
reference, calculate the sequence network
voltages V0, V1 and V2."


texts: Does reference voltage long term drift reset after a power cycle?

texts:
I'm building a 16-bit ADC system to measure the analog output of an ASIC and accuracy is of utmost importance. One subcomponent required for any ADC system is the reference voltage. When choosing a reference voltage and calculating an error budget, a key specification to consider is the long term stability. From my understanding, long term stability is simply how much the output voltage can deviate from the original output voltage over time.
I'm looking into the REF6025 voltage reference by Texas Instruments. From the spec sheet, the long term drift is 80 ppm typical from 0 to 1000 hours. How is 0 to 1000 hours defined? Is this the first 1000 hours after manufacturing? Or is this the first 1000 hours after a power cycle and turning back on? I can't seem to find the answer to this anywhere.
So what I'm really trying to ask is this: will the long term drift reset after turning off and back on again? Or will it effectively be eliminated once the reference has been turned on for thousands of hours, even if I turned it on and off during those thousands of hours?


texts:
I am currently trying to use a DC motor with a lead screw to eventually open an close a window. My window requires around 2 kg's of force to open and the distance that needs to be traveled is 20 inches.

As I lack knowledge in this field, I ordered the wrong motor for my job (Motor). It has too high of an RPM(5500) and not enough torque to even move .6 kgs. Here is the datasheet(My version is NA4565D, datasheet). When powering with my power supply, it only draws about .12 Amps(at 24v). How can I reduce the RPM and increase the torque? If possible without the use of gears, as i don't own a 3D printer to make them. And if there is no reliable way to do this, How can one do it with gears? And how would one calculate the required torque?
Thanks in advance, do let me know if I can give you any more helpful info.


texts:
I'm having a little difficulty to drive this kind of motors using parallel port. Have googled loads of tutorials but unfortunately couldn't found any color codes or types of motors I have. I cannot even order or get Stepper Motor Driver (e.g., Arduino) in my region. So looking for creating my own.

These are the motors:


texts: Embedded System power requirement calculation

texts: How can I measure total power requirement of an embedded system which consists of a lpc2138 interfaced with various other components such as lcd, humidity sensors and temperature sensors. Also the output actions taken are through relay. There is also motor interface. I realised that we can measure total consumption after the circuit gets implemented in hardware by measuring current via multimeter but how to estimate it while in design phase? Which data sheet values are to be considered while calculating power? There are various types of currents mentioned. How do I proceed for calculations? Please help.


texts: what really are: Microcontroller (uC), System on Chip (SoC), and Digital Signal Processor (DSP)?

texts:
The actual question is at the end. But reading that alone might not show you why am I confused. I wrote this post starting with some definitions, assumptions, and speculations and then asking the actual question.

I always think that I know the difference but when I get a question like: "if I put a transceiver with a uC, is that now an SoC?" I go all jumbled up and I don't know how to answer. I recall once I was told that a uC is essentially an SoC. But what proof do I have? But arduino is not on a single chip! I can take out the Atmeg processor off the "board" anytime!

When I check online I get all kinds of answers that confirm or contradicts what I just said directly or indirectly. This is always confusing to me and I blame none-other than marketing people who use these terms loosely and sometimes interchangeably, and the people who follow their lead.

So I decided to look for the fundamental meaning of these three terms: uC, SoC, and DSP. Because for example, when I get confused about voltages in circuits, I always go back to physics fundamentals, ground is not really zero it is just a "reference" and voltages are not "absolute", they a "relatives". This always points me to the right direction. But there is no base to go to when talking about uC. "micro" "controller" is a controller so small that it is in the micro meter scale. But we don't have the nanocontroller term, do we? So this way of thinking wouldn't help.

What I am trying to answer are the following is:

uC is a processing unit with other peripherals and memory with it for
general use, right?
SoC is a full "system" on a "chip". So whatever system you put on a single chip, is an SoC, right?
DSP is a processing unit for specific use, mainly
mathematical operations, right?

Now
Does that mean that everything in a uC they are all required to be
in one chip? because if yes, then uC is in fact a SoC. Maybe a small one, but it is. What about arduino. Probably uC "can" be an SoC if it is on a single chip, but doesn't have to (I am heavily using arduino as an example here).
So arduino is a uC, if I take all of its components and put them in another board and I add XBEE to the mix for example. It is still a uC, right? So when do we say that now it is an SoC? Only when the same stuff are put in a single chip rather than collected in a board?

Till now I think that the above questions somehow answer themselves, but I just want to confirm so I can move on. When I try to think "fundamentally", chip or board "can" be the same, it is just wires connecting the different components. and at this point, what do you define a component? Is it a single transistor or a circuit like an ADC? But I don't want to go there.

The next question is what this post is truly about:

Is a uC  essentially an SoC? A special case of an SoC which one of its requirements being that the whole system is for general purpose use.
uC is general purpose (according to internet) and DSP is mainly to mathematically process signals collected from the real world. But DSP is still a "processor" and a uC contains a "processor". Can I just put a DSP with a bunch or peripherals (let's say ADC and DAC since these are usually used with it) and call the mix a uC? or is that an SoC (since now the mix is not general purpose and hence we cannot call it uC but it is still an SoC)


texts: Simple melody recognition based on a microcontroller

texts:
Is there a way to implement a simple melody recognition using a hobby-level microcontroller board like Arduino or Tiva Launchpad? By "melody" I mean a sequence of 4-5 clear notes, produced by a musical instrument. The device should recognize the stored pattern.

I am starting on this project now and I was wondering if there are any implementations o draw ideas from.


texts: Using open collector as regular 5v output

texts:
I'm trying to use the following IC: SN74S289BJ so that the output is 5v when HIGH and ~0v when LOW, however I'm having problems due to the open collector nature of it, as I've written data to a specific address and the transistor won't sink the pull-up current (meaning that the output LEDs that I use to verify the data are always on) according to the data sheet whenever there is data on a specific output the transistor will be saturated and will cause it to guide the flow of the current to GND.

Currently I have 5v through a 330 Ohms to the collector of the IC 74S289BJ and a LED to show the status.

What would be the correct way to set it up?

Here is my current setup, assume that the address and data are prepared and that
the IC is in read mode (WE is HIGH).

Also, the output is inverted because according to the datasheet the output is the data's complement.

Note: IC U2/3/4/5 in the above schematic are SN74H04N HEX inverters


texts:
A route of 340 km has 17 hops in between.
Effective bit rate per hop is 16.384 Mb/s and average link utilization is 80%.
The message is 486 bytes of payload and 28 bytes of header.
Velocity is 2 × 108 m/s.
How do I find the end to end delay of one packet?


texts: STM32F405 code compatibility with STM32F407

texts:
I have to do a project which will be based on STM32F405VG (100 Pin) but I don't have that MCU at the moment. Instead I have STM32F4-Discovery board which has STM32F407VG (100 Pin) on board. All the specs of both MCUs are same, as shown below including pin numbers, clock, flash, RAM etc except that the 'F407 has 2 additional peripheral interfaces namely Camera and Ethernet.

If I do all my development using the 'F4 Discovery board but select the 'F405 MCU in the CubeMX project creation and flash this code in the 'F407 MCU on the Discovery board .. do all the testing and later when I will get the 'F405 custom board then will I be able to use this code for 'F405 exactly as it is tested on the 'F407 MCU?


texts: Design a full adder of two 1-bit numbers using multiplexers 4/1

texts:
How can i implement the full adder of two 1-bit numbers using only multiplexers 4/1? I created a truth table for a one-bit full adder, which looks like this:

A  = first bit
B  = second bit
Pu = bit from lower position (used to create an adder for multiple bit numbers)
S  = sum
P  = transfer to higher position (e.g. if A=1, B=1 and Pu=0, the sum is 0 and transfer 1)

I made K-maps and used AB as selection inputs of a  multiplexer and Pu as information input.

And finally got to this solution:

Is it correct?


texts: Aluminum Electrolytic Decoupling Capacitors

texts:
It is obvious to me that decoupling capacitors are necessary in proper circuit design. I also realize that different types of capacitors can be more useful depending on the application. However, I have also read in several places (most recently in Op Amps: Design, Application, and Troubleshooting by David L. Terrell) that decoupling capacitors can completely be negated in their purpose if aluminum elecrolytic capacitors are used due to their higher impedance or the leads are not short enough. This ties directly into my question:

Why do I find aluminum electrolytic capacitors being used in decoupling techniques? Is it bad practice to use them or are these few sources I have read from incorrect in their explanations?


texts:
I am trying to make a basic EPROM programmer for M27C322/160/800 chips, mainly as an learning exercise since I know I can buy adaptors for programmers I already own.

I found a very useful resource in the form of an old magazine article that explains how you can make something like this yourself (you can find it here).

I have a similar problem to tackle that the author of this article did, in that several of the pins on my ZIF socket will need to either supply power to the chip or provide an address signal to it. For example, on the '322 pin 32 is the A20 line, but on the '160/'800 that pin is the BYTE line that needs Vpp during programming (+12V). Here is what the author came up with himself:

Now, I'm sure I understand how the power switching works - pulling any of the "xV Enable" lines low individually will allow current to sink through the appropriate resistor and create an output voltage from the '317 based on that resistor's value. What I don't understand is how the A15 control line and associated transistors is working and how this circuit is able to transfer control of ZIF pin 1 between the power signals and address signals... Is someone able to kindly explain what is going on here?

Is it so that if all 3 of the Enable lines (in this case) are driven high, then the output voltage on the '317 will be either +5V or +0V based on the state of the A15 line? It's worth noting for clarity that the "B" line in the diagram is a -1.4V bias, I guess that helps generate the +0V he needs but I'm not sure how.

Thanks for any help.


texts: Using a Single Supply OpAmp in inverting mode

texts:
Is it possible to use a single supply op amp in inverting mode by supplying it with GND -> Vcc?

EDIT: The input signal would never go negative.


texts:
This is a beginner's theoretical question. I was looking at the figures on this site: http://www.electronics-tutorials.ws/amplifier/amp_6.html and noticed that the so called "conducting angle" of a class AB amplifier is given this way:

It is said to conduct between 180° and 360°. What I don't understand is that the output signal is coming from two transistors, additive. I see that a single trasistor in the pair does not conduct in the full 360° range. But the amplifier as a whole does conduct at any angle right? The transfer function of the amplifier won't be a straight line (obviously), but I don't see where the signal is clipped. Please help me understand.

UPDATE: here is a graph showing two functions:

f(x) = min(-0.6, sin(x))
g(x) = max(0.6, sin(x))

I believe that the response of the whole amp to a sinusoidal input is something like f(x)+g(x)


texts: Can you replace a RJ45 connector with smaller connector?

texts:
I'm designing a small board that needs an ethernet connection. However, the RJ45 jack takes considerable space. I would like to reduce the footprint of the connector to safe some space.

Would it be possible to replace it by a (non-standard) smaller connector, like a micro usb connector or a JST PH connector? Which connectors would be suitable and why (or why not)?


texts: How to archieve induction isolation from adjacent inductors on a plane, but no isolation from inductors outside the plane

texts: I am thinking of designing a large wireless charging pad. The idea is to have many inductors in a grid setup, where when a phone is placed on the pad it starts charging from the inductors closest to it. There are weight sensors, so only the inductors directly under the phone will be powered with weight sensors, but how do I prevent adjacent inductors on the plane of the pad from being induced by the inductors that are on. The idea is to charge the phone, not to dispose power to adjacent inductors on the pad.


texts: Best sensor for measuring a dynamic force

texts:
I am working on a project to hopefully measure dynamic loads (weight) within the range of 0 - 100 kg with a minimum accuracy of about 1-4 kg. What is the best type of sensors to use for this particular application?

Currently I have looked at using:

Load cells from a weight scale (I am not sure if this will perform for dynamic loads)
Piezoelectric film (I am unsure about this choice due to inexperience)
Force-sensitive resistors (not rated for application)
Capacitive force sensor (I am unable to find a commercially available one)


texts: USB enumeration problem, cannot reply on request

texts:
I program with LPC2368 on ARM7 architecture and will configurate usb coonection with my pc. After initialization periphery and clock, i try to start usb.
I am using the following scheme fro pull-up resistor in line D+:

For connection this pull-up, i change voltage-level on pin UCON from 1 to 0. After this i receive reset signal from host and message GET_DESCRIPTOR. Then i try to reply on request, but controller nothing sends. I think, problem in hardware. Maybe needed disconnect pull-up resistor after detecting my device?


texts: Connecting a smartphone android camera while charging the phone

texts:
I am hoping for advice. I have a android camera (the same as in this video: https://www.youtube.com/watch?v=AvWIp5vtsEU) and want to connect it to a Sony phone to see if I can use it as a streaming device. However, obviously the phone battery will eventually run out of current so I have to keep it on a charger permanently. The problem is that there is only one micro usb port on the phone. I have connected the positive and negative wires of an usb charger directly to the positive and negative of the probe camera’s cable. It works, but the phone either only picks up the camera and is not charging or is charging but is not picking up the camera. It depends on what is plugged in first. Do you have any advice so it will carry data while being charged at the same time?
Amazon sells the following:
https://www.amazon.com/Kework-Micro-Splitter-Female-Extension/dp/B07ZZ8PNQF/ref=as_li_ss_tl?dchild=1&keywords=Micro+Usb+Splitter&qid=1601039265&sr=8-16&th=1&linkCode=sl1&tag=galtecrev-20&linkId=2b50e736895351b0d5f08d0dd550f486&language=en_US
but it is out of stock and I have tried other local stores but no success.
Regards


texts:
I've routed my PCB but had to change the minimum keepout rules which means I'll now have a lot of DRC errors - most tracks are too closely placed together and that would violate the new keepout rule.

However, I can see the errors only when I route a track.

Is there a way to see all DRC violations at a glance? I'm sure there's a better way of doing it than selecting each track individually.


texts: Can wrist strap be attached to running PC?

texts: Sorry if this is a noob question... I've Googled for instructions on how to use a wrist strap, but most of the answers I've seen assume that you're going to be opening up your PC and installing or working with boards in it, so they all say to turn off the power and attach the strap to the PC case.  My situation is that we have a separate board that will be connected to the PC via a USB, but I will not be opening up the PC and don't plan to turn it off.  I still want to prevent ESD damage to the board.  Is it still OK to attach the wrist strap to the PC case (say, to a screw on the back) while the PC is on?  Or am I risking injury?  (More info: This is in an office building, recent construction, 2nd floor, all carpeted, boss would prefer not to shell out money for a mat.)


texts: L200c power supply, pot won't go down to 0 ohms

texts:
So I'm trying to make a power supply using the L200 regulator. I'm using the circuit in Figure 1. Programmable Voltage Regulator with Current Limiting. I made the circuit after that design. Except that I put a potentiometer in series with R3 to make the current variable. And it does work. The problem that I'm having is this.

I want to current to go up to 2 amps. R3 in my circuit is 0.22 ohms. so 0.45/0.22 = 2.04 amps. BUT the pots I have will only go down to 0.4 ohms, I've tried like 5 of them, is this normal or do I have crappy pots? I don't know how to make the supply go up to two amps.

Is it possible to make the pot go down to maybe 0.1 ohms at least?


texts:
This seems like it must be a common problem but I don't find a clear answer anywhere, maybe my approach is wrong.

I have a DC-DC regulator in my circuit, which has a ripple of 50mV at 200kHz, the current draw is 500mA, voltage output 5V. I want to add a lowpass LC filter to reduce this.
https://upload.wikimedia.org/wikipedia/commons/e/eb/Lowpass_Filter_LC.svg

However I struggle at determining which values I should selected, is there a standard approach in determining these values based on the ripple frequency or otherwise, or how should I go about determining these?

Cheers
Sam


texts: Connecting a high-speed comparator into a computer

texts:
I need to store the output of a stand alone comparator (Hittite HMC875LC3C) in computer RAM drive. Currently, I'm using an 8bit 2GHz ADC (an Agilent PCIe - Acquiris U1071A) to bridge between the comparator and the RAM drive. This solution is redundant, slow, and very expensive (the Agilent ADC is almost $10k).

I would enjoy a better solution where no ADC is present and the comparator connects directly to the PC. Perhaps through a USB port?

Ideally, I would like the comparator to operate at around 1GHz (it supports operations up to 20 Gbps). I would suspect the maximal throughput essentially depends on the computer's processor and interface i/o characteristics.

The comparator outputs pulses are about 60ps long and the Output Voltage High Level is -10mV while the Output Voltage Low Level is about -420 mV. The comparator is emmbeded on a PCB with SMA connectors.

Question: Is it possible to connect a high speed (1GHz) comparator into a PC without having to use an ADC? If so would some form of synchronization be required?

Thanks

Louis


texts: Make energy out of a capacitor in the sea

texts:
First of all sorry about my english it's not my mother tongue.

Problem statement:

A cylindrical capacitor is placed in the sea so that when a wave comes (the water goes up), the water becomes the capacitors dielectric, when the wave has passed (the water goes down) the air becomes the dielectric.
So now when the water is at its highest, i attach a battery to the capacitor.

When the water goes down i detach the capacitor from the battery, this creates an isolated system in which the charge remains constant and can change the potential difference between the capacitors plates.

The force of gravity makes the water that was between the capacitors plates go down, and so it reduces the capacitors capacitance. The dielectric constant of water is quite high (about 81) and the change of capacitance is also quite high.

The charge remained the same but the potential difference between the capacitors plates has increased.
This means that the energy in the system has increased.
So i found a way to harvest energy from the waves movement without moving bodies.... but....

Explain why this system in practice can not really work.
Think about how to make it work (even if with reduced performance, how to make the capacitor stay at the same height is not to be considered).
Estimate how much energy could be made out of such a device.

The attempt at a solution

I think this does not work because sea water is not distilled which means it conducts current. So now there's a current flowing through the capacitors plates which i think would damage the capacitor itself.
Or maybe the battery would get damaged because the capacitor with sea water inside makes a short circuit?

To make it work i think one would need to put distilled water in the capacitor or another insulating material and make it go up and down the capacitor thanks to the waves movement.

I have absolutely no idea how to estimate how much energy could be made out of such a device.

If i'm not mistaken energy in a cylindrical capacitor is calculated as:

$$U = \frac{1}{2}C\Delta V^2$$

So i thought about calculating

Uw = energy when the capacitor is filled with water

and then

Ua = energy when the capacitor is filled with air

and then doing

Uw-Ua = energy generated by the device

But i'm not sure this is right.

What do you think?


texts: Orcad Schematic Capture. Instances vs Occurrences

texts:
Using Orcad capture to create a multi-page hierarchical schematic I used the "Annotate..." option to renumber all parts. First set the them to "?" then incrementally update them.

However, after this when looking at part properties I realized that every single part in the schematic (not just the ones in the hierarchical pages) now had two different versions: the instance in white, and the occurrence in yellow.

Now every single change had to be done to both versions of the part, or I had to make sure that the corresponding occurrence field was deleted, so that it would default to the instance. You can see an example here:

In this case the part reference is different for the instance and the occurrence, while the PCB footprint in the occurrence is defaulting to the one in the instance.

This became very cumbersome and confusing very quickly. For example, copying a part and pasting it elsewhere, would generate a copy of the instance, not of the specific occurrence I was copying.

After many repetitions of "Annotate..." with different settings (and multiple errors while trying to generate a BOM) I found out that by going to every single occurrence and deleting the part reference field by hand, in most cases I could remove the occurrence, making cleanup easier. But I still had to fix a few more issues so that I could get a clean BOM.

My questions are:

What is the purpose of the "Occurrence" in non-hierarchical portions of the design?
How can I clean up these occurrences in the future, or how can I avoid them from reappearing?

Update: I am not sure why, but I again have undesired occurrences messing up part numbering. So I have to do yet another pass through the Annotate and cleanup cycle.

Related question: Hierarchical designs in Orcad Capture


texts:
So I have a K150 PIC programmer, and spent about a week just getting the blasted thing to function in Linux. It managed to program a PIC12F675 twice... and then crapped out. Since I intend to abandon these chips before long, I don't want to put any more money into using them, and so I turned to a project that uses an Arduino as a PIC programmer. A couple hours later, bam, got that set up and re-engineered for my slightly different chip. Some of my best work. Except, it doesn't work.

Looong debugging process short, the PIC isn't entering programming mode. The one thing I managed to get onto this chip was just a "hello world" equivalent of turning on an LED, and that's become a shockingly useful tool; if the LED lights up, it's gone into run mode instead. According to the programming manual, VPP needs to be brought to at least ~8.5 volts, then wait no less than 5us, then bring VDD to ~5 volts to activate programming.

I've got 11.7 volts, and I've tried turning things on at precise times with the Arduino, as well as just manually plugging wires into the board (removing the Arduino from the equation entirely). I thought maybe VPP had to start at true 0 via pull-down resistor (despite no one else seeming to need it), but neither strong nor weak pull-downs made a difference. Of course, I've tried several different chips (though only one has the obvious indicator). Everything meets or exceeds the requirements stated in the programming guide - so what's going on? And why doesn't this seem to be a common issue?


texts: Voltage range shifter from 0V to 3V to -/+1.5V

texts:
I'm trying design from scratch (discrete components and opamps) a circuit that could linearly translate from 0V to 3V range to -1.5V to +1.5V. Can someone provide suggestions and designs of how to do this?

edit:
Ideally, the input and output relationship would look linear. Something like Vo = Vi - 1.5
The input voltage would be AC in the sense that it varies, such as a positively shifted sine wave.


texts: Using mosfets instead of relays for speaker protection - Distortion?

texts:
Traditionally relays have been used for speaker protection in amplifiers to quickly disconnect the speaker in case there is an offset on the output, due to componet failure.

Relays are simple and probably to no contribute to distortion, but their contacts age and can cause problems.

Because of this some designers use mosfets instead:

This circuit (attached) has the first overtone -90dB below which is quite OK and inaudible, but I was more of wondering what causes distortion in these cases and how to select the optimal mosfet for the lowest distortion.

One assumes that V2 drives the mosfets to that they are fully on. One possible distortion source is Rdson variability with Id. For most mosfets this is a flat line for a very great variation in Id so it should be insignificant, but are there other possible sources?

Would a reasonable strategy be to look for mosfets with the lowest possible Rdson and least variablity with Id?

Edit:
Changed to a true floating drive, V2 is generated by a VOM1271T:

Distortion is now undetectable. The one I saw before was caused by Vgs not being constant:

LTSpice model:

Version 4
SHEET 1 880 680
WIRE 112 128 -16 128
WIRE 256 128 208 128
WIRE 480 128 352 128
WIRE -16 144 -16 128
WIRE 480 176 480 128
WIRE 192 208 192 176
WIRE 240 208 192 208
WIRE 272 208 272 176
WIRE 272 208 240 208
WIRE 240 224 240 208
WIRE -16 320 -16 224
WIRE 240 320 240 304
WIRE 240 320 -16 320
WIRE 480 320 480 256
WIRE 480 320 240 320
WIRE 240 336 240 320
FLAG 240 336 0
FLAG -16 128 IN
FLAG 480 128 OUT
SYMBOL nmos 112 176 R270
SYMATTR InstName M1
SYMATTR Value IRFH7932
SYMBOL nmos 352 176 M270
SYMATTR InstName M2
SYMATTR Value IRFH7932
SYMBOL voltage -16 128 R0
WINDOW 123 24 124 Left 2
WINDOW 39 24 152 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(0 1 1000 0 0 0)
SYMBOL voltage 240 208 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 10
SYMBOL res 464 160 R

But back to my initial question.. Am I correct in assuming that I should look for a mosfet with as little change in Rdson with Id? So not this one?

But rather this one:

For a typical power amplifier, the curve would approximate a flat line.


texts: Designing a peripheral for soft core CPU

texts:
I've been implementing a hardware module in VHDL for part of my university dissertation and I want to implement it as part of a NIOS II core in my cyclone 2 FPGA. This uses the Avalon interface, what resources can I look at designing a generic module? I have no idea where to start with this part of my project.

I don't know whether my design will be a slave or a master. Can someone point me in the relevant direction on designing the part of my project.

So I want my hardware module to form some extra instructions of the CPU to speed up the execution of a specific algorithm. So that we have some Assembly call in my C program that uses the hardware encryption co-processor.

My hardware module is DES Encryption module, and i'd like some extra instructions so that I can interface a CPU core to my module.


texts: How to find status (on/off) of any applicance ( light, fan, etc.) connected to an electrical circuit

texts:
There are 4 appliances connected to an electric circuit, how to determine which applicance is on/off and pass that information to an electronic device in binary form.

The idea is to make an electronic device which when attached to the electrical circuit determines whether the applicance is switched on or not and pass the information in binary format


texts: Writing to a 2 byte register from 1 byte registers

texts:
I am an assembly newbie and I am trying to write an assembly routine to write data to EEPROM of a 8051 variant. (Specifically, AT89C51CC03)

In the datasheet, it says that I need to write to the column latches first. For this, I need to fill DPTR register with the address I want to write (2 bytes). As I am working mainly with C, I needed a way to pass the address from C code to the assembly routine. The following link explains the convention:

http://www.keil.com/support/man/docs/c51/c51_ap_parampassreg.htm

which says that pointer parameters are assigned to R2(MSB) and R1(LSB).

My question is, how can I move the contents of these 1 byte registers to DPTR, which is a two byte register? I have a feeling that if I use MOV, I will overwrite the first byte I have written. And the instruction set manual only provides an example for passing immediate values, not from registers.


texts: Should I connect stepper motor case to mains earth or power supply V-

texts:
I have a stepper motor driver, the sockets have the expected V+,V-, etc. However there is a bolt with a grounding symbol on the outside, I think this connects to mains earth? The third pin on a plug? Googling seems to put forward it should be connected to the V- of the power supply.

All the sockets have +,- for inputs and such so I don't think it's for reference but to drain away any electrical noise?

The driver is kelings.


texts: microSD card voltage level- reverse engineering design

texts:
Goal: Adding (back) a microSD socket to a camera that does not have one.

The microSD pads are laid out and appear to be fully connected. Ground is to the ground plane, the data lines are with resistors. When powered up there is 1.6V on the clock line and 3.3V on the MOSI pin (oddly).

However VDD is not connected to anything.

Searching the board on the opposite side there are pads for a SOT-23 device. I've included a photo and, following number conventions, 1 is the lower left, 2 is the lower right, and 3 is the top.

SOT-23-Pad 3 is connected to the VDD pin on the microSD socket.
SOT-23-Pad 2 goes to 3.30V when the unit is powered on.
I can't find a connection to SOT-23-Pad 1, however.

So, am I too far off guessing that this is a PNP transistor pad? Of course that leaves not knowing how the base is pulled as there is a couple of other tiny components missing. You can see in the photo that the two component pads on either side are empty. I haven't had luck ohming things out. I thought there was another trace that went high or low depending on if the card was inserted, but I haven't found it.

Since the camera has 'hot swap' (which you'd never do because you have to literally disassemble the whole thing) what would be an good opinion on just bridging the SOT-Pad-2 to SOT-Pad-3?

The software side of the house I believe I've already modified the necessary file, as the UART log (ugly and limited) appears to show scanning for the card.

If you were me, how would you go from here?

Thank you.

References:
http://elm-chan.org/docs/mmc/mmc_e.html
https://www.vishnumaiea.in/projects/hardware/interfacing-catalex-micro-sd-card-module
http://www.dejazzer.com/ee379/lecture_notes/lec12_sd_card.pdf
https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/
MicroSD Card Slot SPI Signals

Measured on microsd socket:
3   3.30v
5   1.65v

Pinout of card

1   NC      Not used
2   CS      Chip Select
3   MOSI    Master-out, Slave-in
4   VDD     Positive Supply
5   CLOCK   Serial Clock
6   GND     Ground
7   MISO    Master-in, Slave-out
8   NC      Not used


texts: How does a 40 Gbit/s Ethernet interface process packets in silicon?

texts:
A 40 Gbit/s Ethernet interface should have a 40 GHz signal on it. How does common silicon IC technology handle such an exotic beast?

My best guess is that internally various parallel busses are used, but I haven't found much on the internals of these things.


texts:
I have a synchronous datapath in my design that fails negative slack timing check, and I could most likely fix it by putting extra pipeline registers between datapath blocks by changing RTL sources.

I've also tried constraining multicycle path like this (made a simple test project to figure out how timing constraints work, they're new to me):

# tell the router that 'do' should be 5 cycles late
set_multicycle_path -setup 5 -to [get_ports {do}]

I, for some reason, expected the router to put extra registers on the path to 'do' output port to increase latency, but it tried to make a very long net and still failed timing. I do suspect now, that since pipelining involves changing RTL behavior, router and its timing checks have nothing to do with that, and those constraints are only for setting timing requirements.

I then tried to do this:

# don't care how fast the route is as long as it's up
# to 5 cycles
set_multicycle_path -setup 5 -to [get_ports {do}]
set_multicycle_path -hold 4 -to [get_ports {do}]

This fixed timing checks, but still no extra pipelining and now I can't be sure how quick the path is unless I specifically look at timing. I think this would become a problem when constraining a bus that way since the different lines in it might pass timing check, but still might be out of alignment with each other.

So here's the question: is there any way to make the FPGA tools do the work of figuring out how much pipelining a path needs and then inserting it automatically?


texts: reuse Cyclone IV fpga Pasive serial configuration pin for SPI

texts:
Can i reuse pins  DATA0 & DCLK in my application as FPGA SPI interface after configuration (PS) has been completed ?

This are the dual purpose pin options:

if i set "use as Regular I/O" , i will be able to configure after power on the FPGA, once PS configuration is done , i could use this pins as SPI DATA and Clock ....  but not reconfigure de FPGA until next boot...right?


texts: What's wrong with my static relay connections?

texts:
Im trying to use a static relay for the first time. It is an HFS5, supposed to turn on/off at ~5V.

Soldering is not clean but I have triple checked with a multimeter that the connections are ok on lines 1, 2, 3 and 4, that the relay's pins are connected to the lines and that there are no shorts.

1 and 2 are connected to a tablet's 5V DC charger and I checked the voltage is ok on the HFS's input.

However, when I plug in the charger / putting 5V between lines 1 and 2, the connection does not happen between lines 3 and 4 (checking with the multimeter again)

Any idea what can be wrong in your experience ?


texts:
I saw this circuit and I want to find the relation between Vin and Vout.

Assuming ideal Op-Amps, If VB>0 then the diode will be ON and A2 acts as a buffer so VB must be equal to the voltage of Virtual short circuit of A1 and then VB=0.

If VB<0 then the transistor and diode will be OFF and there is no way from Vin to VB.

If VB=0 there will be no relation between Vin and Vout and I think this can't be the answer.

What is the true method of analyzing this circuit? (I can find the relation of VB and Vout. my problem is in finding the relation of Vin and VB)


texts: How to build a timed circuit with an LCD?

texts:
I am looking to build circuit that does the following:

Be able to operate a motor through a chargeable battery for a certain amount of time
display the battery levels on an LED
display the countdown for the time the motor is running on the same LED

I am a mechanical engineering student and am unsure what kind of a circuit mechanism I will have to use? I could use an Arduino and code the entire circuit but I am struggling for space and require something that requires less space and can be fit in a small space. Any assistance will be much appreciated.


texts: Cable length and voltage drop in offgrid solar installation

texts: I have connected my Lithium-ion battery pack(11.1v 100ah ) with my Epever MPPT charge controller using 5M length of 8 AWG cable. when i put load which consume around 12A , the charger controller shows 11.4 V as the batter voltage. But when i check the voltage between the battery terminal it shows as 12V.Will it be the problem of cable length?


texts:
I tried to create a custom pad shape in altium desginer 14 for my pcblib but i missing a option in altium to assign a designator to the region.
i already assigned solder/paste mask and now placed a pad in the middle of the region but i have doubt what this is the appropriate way.

i followed the instruction in this video http://www.altium.com/video-creating-custom-pad-shapes


texts: Confused with understanding the text about high input impedance and coupled noise for an electret microphone

texts:
I have a problem with understanding a text's paragraph about the use of FET as a preamplifier. It claims that it reduces the coupling noise for an electret microphone before it is amplified in the next stage. Here is that section:

  The electret microphone has a very high output impedance because in
  practical microphones the capacitance of the diaphragm is very low.
  This requires a very high impedance load for the microphone. To prevent
  noise pickup by the high-input impedance amplifiers, an FET
  preamplifier is provided within the microphone and provides a low
  output impedance.

What is the text trying to explain here? The FET in the capsule for preamplification already has a very very high input impedance. So it can already pickup noise. What is the point of saying "to prevent noise pickup by the high-input impedance amplifiers" here? It seems to me if the noise pickup issue is due to the "high-input impedance"; then by adding a preamplifer FET they are again coupling the mic capacitor to a high-input impedance isn't it?

I don't understand how they mitigate the noise by adding another high input impedance device(FET) if the noise is related to high input impedance.

Edit:


texts:
I have a 5000 pcs. Package of PU392 transistors, but I cannot find a datasheet for the PU392. It is a NPN transistor in a modified TO92 case with cooling from National Semiconductors.

Goggle and the various datasheet websites do not find this transistor.
How can I find the datasheet for the PU392?


texts: Both sides of a voltage level shifter connected

texts:
The TXS 0108E is a level shifter circuit, performing, in my project, a shift level voltage from 3.3V to 5V . Because of a design error in the wiring diagram, I left some pins with the same name on the connectors and their respective sides of the TXS 0108E IC. Not all pins, only 4.  The result was that these 4 I/O pins now are connected in the pcb.

These interconnected pins are not required and are not used in the circuit, so that on both connectors, these pins will be left unconnected.

However, I can not predict if there is a problem in leaving the pins on the A and B side of the TXS0108E  connected, and if this can interfere with other signals making noise or reducing the life time of the IC.

Below is a diagram of the internal circuit of the TXS0108E IC

Does some one has any idea of what can happens ?

[edited]

I noted that a current will flow from Vcca to Vccb once Vcca > Vccb. But, which kind of damage it can cause ?


texts: I'm looking for an advice how to select capacitors for my SEPIC converter. I have done calculations, but I haven't find Cin, Cs and Cout yet. What seems like a problem is that there are few work papers that recommends to use capacitor "capable to endure calculated current ripple". How can I be sure that the selected capacitor would endure calculated current ripple? I know that ESR is what produces heat in capacitor, but how should I know if some ESR won't produce enough heat to overheat my capacitor? For example, I got that RMS current for an input capacitor is 2.2A, and some voltage ripple condition tells me that the capacitance of that input capacitor must be greater than 180uF. So I'm having a problem how to choose those current capable capacitors on my own. Can someone helps me?


texts: Is it possible to send AT commands through TCP?

texts:
I have a SIM900 GSM/GPRS device, I can send AT commands through HyperTerminal and everything is fine. I can configure GPRS connection through AT commands:

AT+CGATT=1
AT+CIPMUX=0
AT+CSTT="INTERNET","",""
AT+CIICR
AT+CIFSR
AT+CIPSTART="TCP","IP","PORT"

With these configuration I can make it connect my PC (using port forwarding on the home router). I created a TCP server in C# and the server accepted the TCP connection from the device. My question is, is it possible to send AT commands through TCP and execute them ? The server sends AT commands to the device and they are received but as data not commands.


texts: vario trafo 4 terminals, trouble shooting

texts:
So I got a bare vario trafo and with 4 terminals,  2 terminals are constantly showing around 3 ohms (primary maybe?) the to other 2 terminals can vary in ohm as I turn the wheel (secondary?). So I tried 220 volts on primary and it smoked and made a loud humming noise, after it was hot, I quickly turned it off.
The resistance didn't change so I'm thinking there might be a chance to get it to work. what to do now? I read other places that its a good idea to try with low voltage first. But should I put a fuse in series with it or a load, I don't want it to burn further?
Thanks for your help

By the way the it looked like there was some tiny scratches on the coil before i started testing so I gave it some floor lacquer, It did the job i think.


texts: Force microphone on TRRS connector without a mic connected

texts:
I have a TRRS connector for my Android phone. I want to be able to enable/disable the mic on the cable using a button.

So for this I have connected a 1.2 kOhm resistor to a button and when its 'on' it will create a bridge over the Mic and ground connector, successfully muting the mic. If I leave it 'off', the microphone inputs data normally.

The problem is, the only way the Android phone uses the external MIC input  when connecting the cable for the first time is when the button is 'off'. If I connect it when the button is 'on' it will not switch to the external 'muted' mic.

Is there a way to force this behavior, connecting a 'muted' microphone over the TRRS connector?


texts: Less than 180 phase shift in inverting amplifier

texts:
I'm simulating (click here) a standard BJT - CE inverting amplifier.
However, as you can see in the plot, the phase shift between voltage at the resistor and signal voltage is very different from 180 degrees. I've heard that it has something to do with the delay due to RC group, however I wasn't able to better understand this effect and to calculate the real phase shift.

Could you help me?


texts: Recommendation on Optical Sensor (being used for Fingerprint Scanning)

texts:
When I have researched available optical fingerprint sensor modules, every one comes with a processor that takes the sensor image data and processes it.  They all appear to keep the fingerprint data internal to the module, and only allow commands to be sent via UART in order to scan/store/compare.  Most appear similar to this Adafruit Fingerprint Scanner.  I am looking for an optical sensor that transmits just the raw image data so that I can process it myself.

I need this, as a part of my research is to recreate algorithms that identify/compare fingerprints.  As such, I want a module that I can interface with a processor, where the sensor module transmits the image data back to my own processor, and from there I can process the data as I so wish.

One alternative would be to purchase the Adafruit module, and then simply bypass the on-board processor in favor of my own, but I cannot seem to find any documentation on how the on-board processor communicates with the optical sensor.  I would need to know this in order to identify the communication standards being used to capture the data.  As such, I think my best alternative is to reach out for help in finding an optical sensor module that has proper documentation that I can reference, that is suitable for fingerprint scanning.

My background is in embedded design, but I have no prior knowledge of optical sensor modules.  If anyone has any familiarity with optical scanners, and has a recommendation for one that would be suitable for this application, I would very much appreciate hearing your thoughts!


texts:
How is an active output clamp implemented on a high-side MOSFET switch?

If there are several possibilities, then I am focused on how it's implemented on Freescale's MC15XS3400.

I can wrap my head around how it's done on a low-side switch, but the high-side has me stumped. With reference to the schematic below (of a low-side switch), when the MOSFET is turned off, the source voltage overcomes the TVS and drives current through \$R_1\$ leading to \$V_g > 0 \$ and opening the MOSFET's channel a bit to allow the inductor to demagnetize (or, at least, that's how I understand it).

The reason I included this explanation/schematic is to highlight my expectation that there be some sort of resistor near the gate perhaps which will pull-up the voltage when current flows through the TVS, wherever it happens to go on the high-side version.

simulate this circuit – Schematic created using CircuitLab


texts: Designing a Smaller 2000W Transformer PCB to Run 220V Heating Element on 110V

texts:
I'm trying to design a step up transformer that can run my 220V heating element on 110V outlet. I've looked for such transformers through retail, but most of them are bulky and heavy.

Is there a way to design a smaller version of this bulky transformer, that will be able to provide 2000W of power to my 220V heating element running from 110V outlet?


texts: Multimeter Always Reads 60Hz Measuring a CD4060 Pierce Oscillator

texts:
Using a CD4060 IC I’ve built a crystal oscillator circuit similar to the one in the image. I’m trying to use my klein mm400 multimeter to measure the oscillation frequency so I can get a rough estimate.

Where should I be placing the probes in that net? I’ve tried placing both across a resistor connected to the output pin, but the meter always reads 60Hz.

Perhaps the messy wires are disturbing the probes? This circuit looks horrendous because I don’t have any resistors larger than 1M.. I should really cut these cables too to shorten them.

This is not my actual schematic but my circuit is set up the same way. I am using 22pF caps, 47k for Rs

Update: My circuit is now corrected and oscillates reliably but the multimeter still has the same issue. Read my answer down below to see my new circuit.


texts: I have built TRIAC circuit below which I got off the internet. Without the snubber circuit works good, but with snubber the TRIAC is always on. I'm using 9v ac just for testing purposes. Can someone explain why snubber makes it so TRIAC is always on?


texts:
I would like to use N-channel as a touch switch which will be an input to the microcontroller. Currenty I am concerning about power draw. The whole device will be in metal case and I am planing to connect this case to battery GND. Now, if I use the Nmos connected like this (R3 is a touch plate):

i will have in off state power consumption on R1.
Only way how to avoid this comsumption is put a touch plate instead of R2 and switch to VCC.
I am asking, does make sense to make a metal case connected to VCC instead of GND? Or is better to use a P-channel mosfet wich will be grounded during on state?
Is there a way to use high impedance of uC imput to make it without mosfets?
EDIT:
I forgott to clarify, the touch plate will be made like mosfet gate to metal case touch switch.
EDIT:
Until now I see the most suitable solution to use a P-channel like this (no waste, no need to low finger resistance):


texts:
I'm building my own PCB to power 8 in-wall LED's for a stairwell.  I'd like to protect the LED's with fuses, but I'm unclear on how the voltage on fuses work.  My specs are as follows:
LEDs:  5V, 600mA, 3W LED (x 8)
LED Driver Output:  +5V, 5.0A, 35W DC
I think I understand how the amperage works with the fuses, but I'm not sure if the fuses need to be 5v or if they can be higher.
I'm not an electrical engineer, so I don't know what I'm doing, but here's where I'm at:

I have two questions.

Can I go with a higher voltage fuse such as this:  https://www.amazon.com/dp/B00X772B3M/ref=cm_sw_r_sms_c_api_i_P9r3EbTMEDREB
Is there anything I'm missing in my circuit?

I appreciate any advice anyone can give.
Regards,
TY


texts:
The TI's battery management IC BQ2403x have the chip enable signal which needs to pull up when working.  There are four potential power sources to enable this CE signal which are: AC, USB, BAT and System(LDO or OUT) power. However, I think none of them is proper(Maybe I haven't understood this signal correctly).

AC or USB or BAT power

None of the three ports must be present when working, user may just use battery or usb or other, so either can be used to power the CE signal alone.

System Power

Before the CE is enabled, the system will not get any power, so it can't power the CE signal.

The idea I can have now is to connect AC/USB/BAT power with 'OR' gate to power the CE but I feel it's kind of complicated.Is there any simple way to power the CE signal?


texts:
I am trying to design a 4th-Order bandpass filter with the following specifications; centre frequency 30 MHz, bandwidth 5 MHz and of course minimising loss.

I present my current design below which I determined using the ELSIE simulation design program. The problem is I am not very confident in electronics and I am not convinced about my circuit diagram.

simulate this circuit – Schematic created using CircuitLab
If anyone has any advice or can spot any mistakes I would appreciate any thoughts!

Cheers!

Quick Edit: I have attached the output schematic of my ELSIE simulation in case it is useful to anyone:


texts: What is a reasonable current rating for a catch diode for switching applications?

texts:
When selecting a catch diode for a non-synchronous buck converter, is there way (or even a general rule-of-thumb) to determine a safe current rating?  Most diode spec sheets will show the max average current (based mainly on thermal capabilities) and usually a non-repetitive peak current, often 10-50 times higher than the average.  But in a switching converter it will be repetitive, and I have very rarely seen this specified.

If for example I expect 800mA output from a regulator, and I expect up to 1.6A peak current through the diode, can I select a diode with a 1A (max. average current) rating?  What is safe to assume about the max peak capability?  Of course a 2A diode would be safest, but is it necessary?


texts: What will happen in theory if a 240V single-phase AC motor is run on 120V?

texts:
The motor is a A.O Smith Century 56-Frame Two-Speed motor. It runs on 240V single-phase. Here's the only reference I found (PDF), search for B2235.

If such a motor would be hooked to a 120V circuit, would it develop enough torque to start? Would the rotational speed be the same? I
am also interested about the effect on capacitor(s) and centrifugal switch.

Edit: Edited to just put emphasis on the theorical aspects because I had a feeling the answers would tend toward how to actually get 240V to the motor.


texts: Differentiating between a square wave or sawtooth wave with a circuit...?

texts:
I want to build a simple sensor that takes a 100 kHz square or sawtooth wave with a known amplitude and outputs a high if it receives a square wave or a low for sawtooth.

I'm pretty sure this requires some sort of comparator, but I'm not sure how to approach this problem myself. Could anyone outline some sort of approach? (I'd like to figure out the details).

Thank you in advance!


texts:
i am using the LM741 amplefier
i want to invert a negative voltage (-10V)
to positive voltage (1V), my problem is :

i dont get the 1v DC at the output.
i get an ac signal at my oscilliscope.

and i dont know why ?
this is my schematic


texts: Battery pack a little bit damaged. Should I throw it out or repair?

texts:
Today my 48v 15Ah LiFePO4 ebike battery  fell off from my bicycle and got a little bit of road rash on the corner:

It still works. Does not seem to be heating or discharging on its own.

However, between battery minus and a tiny bit of the exposed area (not all exposed area in the picture is metal though) there seem to be +2V, which is making me somewhat nervous.

What would happen if I would simply apply liquid electrical tape on that area and call it a day?

Thoughts going on in my head:

Could internal short happen and battery catch on uncontrolled fire?
Does LiFePO4 chemistry play any role in this as well and add to the safety?
I don't know what form factor cells are inside the battery pack and if that plays any role as well. Obviously dont seem to be anything durable like 18650.
Should I simply throw away this battery and get a new one?

P.S. since its Halloween I am up to hear all horror stories on what may happen...


texts:
I would like to fab some custom LEDs Assemblies.

Embed a resistor in the plastic, is there a smart way to go about doing this?

I know Alibaba other than that nothing really.


texts:
I am reading 4 bytes from EEPROM to make a float value.

The specific eeprom I use(24Lxx Series) has 0xFF as default value.

So, if I read four bytes of 0xFF into float variable, it will have 0xFFFFFFFF

I want to be able to check above condition.

However, statement, if(floatVariable==0xFFFFFFFF){....} doesn't check out to be true, even if the floatVariable does have 0xFFFFFFFF inside(checked via debugger).

Is there any way I can do that?


texts: Make MIDI messages and audio signal transit in the same jack cable

texts:
I know it's a crazy (bad) idea, but still: I hate having many cables attached to a music instrument when I move in the room. Let's take the example of a Akai MPC500 sampler: it is battery powered (so no power cable needed), but I still have 2 cables attached to it:

a long 6.35 mono jack cable (unbalanced, it's ok for this purpose)
a MIDI cable (DIN connector on both ends)

Question: could we make both a audio channel (20Hz-20kHz signal) and MIDI signal (serial data @31250 baud) transit in the same jack cable (i.e. only 2 wires: ground and signal)?

Probably with a filter, like when with ADSL 20 years ago, we could use Internet and someone talking on the phone (not VOIP but old analog phone) at the same time.

Something like that:


texts: Can't write to serial from microcontroller

texts:
I have the following items:

ATMEGA328P-PU
POLOLU - PGM03A (Programmer)
https://www.pololu.com/docs/pdf/0J36/pololu_usb_avr_programmer.pdf

So far, I've been able to write output to data pins. Now I want to attach a sensor, but I need to see the sensor output on my computer.

I'm trying to make the micro-controller write 'K' character to TX pin and as far as I understood I should be able to connect to /dev/ttyACM0 using putty or screen from my Linux computer and see the output, but when I run the following commands, I get no output, I also tried ttyACM1, ttyACM2 but still nothing:

 putty /dev/ttyACM0 -serial 9600

OR

 screen /dev/ttyACM0

Code:

#define F_CPU     1600000UL
#define BAUD      9600
#define BRC       ((F_CPU/16/BAUD) - 1)

#include <avr/io.h>
#include <util/delay.h>
#include <stdlib.h>

int main( void )
{
    UBRR0H = (BRC >> 8);
    UBRR0L = BRC;

    UCSR0B = ( 1 << TXEN0 );
    UCSR0C = ( 1 << UCSZ01 ) | ( 1 << UCSZ00 );

    while( 1 )
    {
        UDR0 = 'K';
        _delay_ms(1000);
    }

    return 0;
}

Makefile:

CC=/usr/bin/avr-gcc
MEGA=328p
CFLAGS=-g -Os -Wall -mcall-prologues -mmcu=atmega$(MEGA)
OBJ2HEX=/usr/bin/avr-objcopy
PROG=/usr/bin/avrdude
TARGET=serial

program : $(TARGET).hex
    $(PROG) -c avrispv2 -p m$(MEGA) -P /dev/ttyACM0 -e
    $(PROG) -c avrispv2 -p m$(MEGA) -P /dev/ttyACM0 -U flash:w:$(TARGET).hex

%.obj : %.o
    $(CC) $(CFLAGS) $< -o $@

%.hex : %.obj
    $(OBJ2HEX) -R .eeprom -O ihex $< $@

clean :
    rm -f *.hex *.obj *.o

When I run the micro-controller I see the TX LED blinking, so I'm guessing the micro-controller is actually sending the data, but I'm just not reading it correctly on the computer side. Any suggestions?


texts: Re-programming an AVR from another MCU over SPI?

texts:
Many AVRs have the capability to be ISP'd - or in system programmed over SPI. I have a project where the entire device can get firmware updates, and I'd like to also update the firmware on it's front panel from the main micro. Since the front panel is conveniently connected through SPI, I've had the idea of just re-programming it from my main MCU over SPI.

That's the ISP method, which would be quite easy and would not require me to write a boot loader. If I can't do the ISP, then of course I will be needing a bootloader.

So basically - can another MCU re-program the ATMEGA644 over the SPI bus?


texts: Circuit only works when o'scope probe is connected

texts: I am working on a circuit with a PIC mcu and an LCD display on a breadboard. The PIC communicates with the display via I2C. For some reason I can only get the communication to work properly when my o'scope probe is connected to the SDA line of the I2C interface. I know the communicate is working because the display shows my text. If I remove the probe and then restart the firmware the display stays blank. Any ideas what is happening here? I am using 4.7k pull-up resistors on both the data and clock lines of the I2C as recommended by the PIC manual. I also tried swapping the resistors out with 1k's and 10k's but that didn't seem to help.  Also, it doesn't matter if the ground clip on my probe is connected to the PCB ground or not (so I don't think it's a grounding issue). Any ideas what is going on here? I know I should really get a real PCB made but I wanted to prove the design was good on the breadboard first.


texts: There are three GND pins on the Arduino UNO pinout. As I'm trying to design a mixed signal PCB to act as an Arduino Shield, I wonder how I should connect those pins, i.e. to the analog or digital ground plane? Or can I assume the left pin row is digital (thus on digital ground) and the right analog (next to the analog inputs, on analog ground)?


texts:
This is my first question on here as I'm tinkering with some audio devices, etc. My intention is to create an audio input jack

from a dismantled audio tape head as seen on this picture:

So that with the end result you can do tape experiments like these.

Now, I'm a real n00b when it comes to electricity etc., so I have no clue what cables from the tape head I should attach to which from an audio jack cable.


texts: converting STM32F4 discovery USB mouse example to gamepad

texts:
I own a stm32f4 discovery board, for which a demonstration project can be downloaded here:
http://www.st.com/web/en/catalog/tools/PF257904

This demo consists of software to use the board as a usb hid mouse, using the accelerometer to control the mouse movement. I want to change this into a gamepad, for now I'm leaving the other parts of the descriptor the same, so I only changed the usage from 0x09,0x02 (usage: mouse) to 0x09 , 0x09 (usage: gamepad). (these values can be found in the usb_hid_core file)

But after this change the computer still sees it as a mouse, but one that is not functioning correctly. What else should I change?

Any help would be greatly appreciated, I have been trying all kinds of things for weeks now, but nothing seems to work.

the usb_hid_core file can be found in this file at this location:

stsw-stm32068\STM32F4-Discovery_FW_V1.1.0\Libraries\STM32_USB_Device_Library\Class\hid\src

(i was under the impression that all that i would have to change would be this line in the descriptor to make it look as a gamepad, since the data that is send will still comply with the descriptor then, i also tried changing it to a very simply device that sends just one byte before changing it into a a gamepad, and i tried changing various other things like hid class). This is how it shows up after i change it to a gamepad (but is doens't work then): http://hmsprojects.com/USB-invoerapparaat.html


texts: How can I convert ADXL335 acceleration data into displacement?

texts: I am using ADXL335 3 axis accelerometer to measure wave elevation on a tank. The data I receive from the sensor is acceleration. I need the displacement of the sensor in x,y and z direction with respect to the stable state. I tried converting acceleration to displacement with double integration but the error is large. Can someone suggest a better was to convert acceleration into displacement without error ?


texts: Why are these two potentiometers affecting one another?

texts:
Let me first say, that I am no electrical engineer so thanks for taking the time to deal with a layman.
Background
In my workshop, I have two sets of speakers hooked up to a common 3.5mm audio source using a "Y" adapter.
One set of speakers is high on top of a shelf and for louder music when barbecuing or whatever.  The second set is down low at the work bench level and is for listening while working at the work bench.
I have built a little panel with a couple of potentiometers that I can use as volume knobs to control the relative volume of each speaker set independently.
Problem
I wired everything up yesterday and all works as expected except that when I use the speakers together, turning one volume knob to zero kills the signal to both sets of speakers.
To be clear, turning just one knob does not lower the volume of the other set of speakers as it does it's own set of speakers, but when I turn the knob 100% to the "off" position, both sets of speakers go silent.
What am I missing here?  I can't understand how in the world one knob would affect the other set of speakers at all.
Here is a crummy wiring diagram:

Thanks in advance.


texts: Typical resistances of jumper wire and silver foil

texts:
What is the typical resistances of the following or how can I go about calculating this approximately?

1) Typical jumper wires used in prototyping with breadboards
2) a silver foil with dimensions length:5cm, width:1cm


texts: Temporary but hands-free JTAG/SWD connection

texts:
I have a PCB that will have very little clearance on both sides so that putting a normal Cortex SWD .50 spacing connecter is too big. However, I'd still like to have the option of connecting via SWD to the target if the need arises for debugging. Since we're talking debugging and not just programming, holding pogo pins against the target is not feasible and I don't want to build custom jigs for every little board I make.

I know that Tag-Connect exists but there's no way I'm going to spend that kind of money on cables.

Are there any easy to implement solutions that allow a temporary but hands-free connection to a board for debugging? Preferrably with just a footprint and no actual components on the board.


texts: Deriving two independently stoppable clocks from one clock

texts:
I am trying to do some complex, pipelined computations in FPGA that involves storing partial results in block ram and retrieving them later. The problem is, the number of partial results that needs to be stored is very hard to reason about and depends heavily on implementation details. What I want to achieve instead is to divide the circuit into a producer and a consumer, and halt the producer when the system runs out of block ram by stopping its clock, as shown in the ascii drawing below.

input clock  |-------| -----------------------------------------------
-------------| ????? | individually controllable clocks in same domain
             |-------| -----------------------------------------------

Is this achievable?
Thanks


texts:
I'm new to discrete logic (I come from the spoiled Arduino/$1 ATTiny generation) and I'm trying to design a safety circuit that would assert FAIL on the second attempt to ENABLE the OUTPUT if the SAFETY input hasn't been disengaged(and re-engaged) after the first attempt.

Simply put, I am trying to prevent the device from running 2 times in a row without being reset via the SAFETY switch after every run.

Here is a simplified signal diagram and simulation of the circuit.

I need to create a truth table for this circuit, but I can't wrap my head around even whether this is a synchronous or asynchronous circuit, because the Clock (well Gate, or Enable, however you want to put it) is connected to one of the Inputs, and I have a monostable multivibrator on the Set of the latch, which actually changes state during the clock cycle.

Here is a more detailed signal diagram, including all the inputs and outputs that I think are relevant to analyzing the states of the circuit.

Please help me make heads or tails out of this, and if you have any optimization suggestions, I'm open for all input!

Your wisdom is much appreciated!

PS.: Thanks to everyone who commented & showed me I need to go deeper!


texts: How can I wire this RF receiver up to control a low-voltage motor?

texts:
The instructions are sparse (for me) but I figured you guys would know how to hook this thing up in a jiffy. It requires a 12V power source.

and here is a picture of the terminals


texts:
What are the typical values of reverse saturation current of a LED? In particular is it possible to have a reverse saturation current of \$10^{-17} A-10^{-18} A\$ for a (red) LED?

For a silicon diode the typical values are \$10^{-9}A-10^{-12} A\$. Do LEDs have much lower reverse saturation currents usually?


texts: Using ADC interrupts and TIMER interrupts at the same time

texts:
I'm a programmer and not jet experienced with arduino or any microcontrollers. Especially the technical side.

I soldered a 6x8 RGB Led Matrix and use binary coded modulation http://www.batsocks.co.uk/readme/art_bcm_3.htm to mix the colors.

The Leds are controlled by 4 74hc595 shiftregisters.
Basically I shift out the bits to control the really fast during a timer interrupt.

Now I want to influence the color of the leds by measuring sound frequencies with an Electret microphone breakout board. To achieve fast frequency detection I use a technique described here http://www.instructables.com/id/Arduino-Frequency-Detection/#step1.

It is based on ADC interrupts.

Both impementations work alone but when I try to bring the code together it breaks.

The timer and the ADC are initialzed like this:

cli(); //stop all interrupts

/////////////////////
//initialize TIMER//
////////////////////
TCCR1A = 0;
TCCR1B = 0;
TCNT1  = 0;

OCR1A = 1;            // compare match register
TCCR1B |= (1 << WGM12);   // CTC mode
TCCR1B |= ((1<<CS21)|(1<<CS20)) ;
TIMSK1 |= (1 << OCIE1A);  // enable timer compare interrupt

//////////////////
//initialize ADC//
//////////////////
ADCSRA = 0;
ADCSRB = 0;

ADMUX |= (1 << REFS1); //set reference voltage
ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from          ADCH register only

//ADCSRA |= (1 << ADPS2) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500kHz
ADCSRA |= (1 << ADATE); //enabble auto trigger
ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
ADCSRA |= (1 << ADEN); //enable ADC
ADCSRA |= (1 << ADSC); //start ADC measurements

sei(); //start all interrupts

So my question is - Is it even possible to use those interrupts together? And how do I have to configure them to make it work. Or is this a dead end?

EDIT
The Timer interrupt:

ISR(TIMER1_COMPA_vect)          // timer compare interrupt service routine
{
zaehlbit <<=1;
//reset timercompare and zaehlbit
if( zaehlbit == 0 ) {
  OCR1A= 1;
  zaehlbit  = 1;
}
//latch low
bitClear(PORTB, latchPinPORTB);

//red
for (int i=0; i<8; i++){
  // clock low
  bitClear(PORTB, clockPinPORTB);
  //check led position and brightness
  //and set Bit on Datapin if zaehlbit in Brightness
  if (ledCounter&led && zaehlbit&red){
    bitClear(PORTB, dataPinPORTB);
  }
  else {
  bitSet(PORTB, dataPinPORTB);
  }
  // clock low (register bit)
  bitSet(PORTB, clockPinPORTB);
  ledCounter >>= 1;
  if( ledCounter == 0 ) {
  ledCounter  = 128;
 }
}

//shift timer compare and set timer back to generate delay (Bit Angle Modulation)
OCR1A <<= 1;
TCNT1 = 0;
}

I do the same for-loop for the rows and the other colors. I just left it out because it looked confusing. The compare match register is shifted left during the interrupt and the timer is set back to generate a "growing" delay. There is one interrupt per cycle. It runs at a clock/32 tickrate

The ADC interrupt looks like this:

ISR(ADC_vect) {//when new ADC value ready

  prevData = newData;//store previous value
  newData = ADCH;//get value from A0
  if (newData > prevData){//if positive slope
    bitSet(PORTB, ledPORTB);//set pin 12 high
  }
  else if (newData < prevData){
    bitClear(PORTB, ledPORTB); //set pin 12 low
  }

}

The ADC interrupt is triggered everytime a value from A0 is ready.
In the mainloop I just try to set some leds but it doesn't work.


texts: What does this Mosfet & Bipolar Transistor power circuit do?

texts:
I'm trying to design a raspberry pi HAT prototype and I came across this circuit below. I'm not familiar with power electronics but i'm curious of what this circuit is trying to accomplish. Any help would be appreciated. Thanks

Image of schematics