3 votes

Square wave generator using RPi 2

You can generate a square wave in quite a few ways. The simplest and probably the best is to use one of the clocks or the PWM peripheral. Have a look at my pigpio library. From the command line ...
joan's user avatar
  • 71k
3 votes

How to use 2 GPIO pins for 3 buttons

Just for reference, there are two well-known approaches for addressing multiple keys with fewer pins: voltage ladder if you have analog pins and key matrix if you have digital pins. The Pi itself has ...
Dmitry Grigoryev's user avatar
3 votes

Real time + High frequency ADC data reading with Raspberry Pi 4

Linux is not a real-time operating system. You will not be able to achieve consistent sampling times using the standard Linux environment. I have used DMA bit banging to get accurately timed SPI ...
joan's user avatar
  • 71k
3 votes

Raspbian Stretch lite doesnt send HDMI signal on second boot

Common Hack I have had that kinda problem, pi is booting but nothing appeared on the monitor or sometime flashes after intervals. after searching out, someone mentioned there that it might possible ...
Musab's user avatar
  • 41
3 votes

Rasberry Pi signal repeater/extender

Yes, there is a better alternative which has nothing to do with the Pi. Get an RC radio (the one they use to control model cars / boats / aircrafts). Those usually come in form of handheld controllers ...
Dmitry Grigoryev's user avatar
2 votes
Accepted

SignalR on Mono Raspbian

Yep, @Aurora0001 you're right, thanks! So, I did only sudo apt-get install mono-complete which installed the Mono 3.2.8 instead the latest version. I forgot add the Mono repository to my system: ...
MihailPw's user avatar
  • 153
2 votes

How can Rpi read ADS1256's negative values?

Your ADC isn't working because you're exceeding the ABSOLUTE MAXIMUM RATINGS listed in your question: Analog inputs to AGND: −0.3 to AVDD + 0.3 (V) In other words, this ADC cannot measure negative ...
Dmitry Grigoryev's user avatar
2 votes
Accepted

How can Rpi read ADS1256's negative values?

am I correct to assume that this ADC can only receive analog inputs above zero? Well, the datasheet says the analog input range is + - (Vref * 2) / PGA. In other words, if you set Vref = +2.5V, ...
tlfong01's user avatar
  • 4,675
2 votes

PedalPi, lag when piping in data

In your code Output code you have not define bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_64); // 4MHz clock with _64 , you not divide the clock. Per default the clock freq. is 250MHz, so ...
Ephemeral's user avatar
  • 2,157
2 votes
Accepted

Interpreting 10-bit ADC output

In general, if your ADC is 10-bit with a 0-1023 return range, this value indicates a voltage that is proportional to the V_REF (reference voltage) input on your ADC. If your V_REF was 5 V, then a ...
Fred's user avatar
  • 4,552
2 votes

How to enable sending keyboard signals while in SSH?

The signal SIGUSR1 is not among the signals that can be generated by the keyboard. For the signals that can be generated, see the manual page of stty or the output of stty -a. That means that the ...
RalfFriedl's user avatar
  • 2,188
2 votes
Accepted

Sending a NEC like signal via a GPIO

If you are a decent programmer you can use pigpio waves to generate the signal. This is a Python example which uses the kind of techniques you will need to use. http://abyz.me.uk/rpi/pigpio/examples....
joan's user avatar
  • 71k
2 votes

Waveshare AD/DA espansione board setting sampling frequency

3 signals at 10 kHz is exactly 30 kSPS, so you should be able to sample all three channels at the same rate, then throw away unneeded samples on slow channels. Sampling different channels at different ...
Dmitry Grigoryev's user avatar
2 votes

Monitor only recognises the signal when started first

Bullseye update There is now an option in raspi-config Display Options to set VNC Resolution for headless operation. The method below prevents other config.txt options from working. You need to ...
Milliways's user avatar
  • 60k
2 votes
Accepted

How to use 2 GPIO pins for 3 buttons

You could try something like the following - which will at least isolate buttons. Pushing the centre button will activate both inputs - the others a single input. Strictly no diode is required on the ...
Milliways's user avatar
  • 60k
2 votes

GPIO configured as interrupts detects noise of the engine even if isolated

Any GPIO which is not connected to a voltage will float between high and low. You need to give the GPIO a fixed voltage by supplying a pull to 3V3 or a pull to ground. The weak internal pulls (about ...
joan's user avatar
  • 71k
2 votes
Accepted

Receiving noise signal on input pin after connecting jumper wire to GPIO pin Raspberry pi 4

Until a voltage is applied to a GPIO it will float between high and low. https://www.mouser.com/blog/dont-leave-your-pins-floating
joan's user avatar
  • 71k
1 vote

What is the maximum baud rate achieved in raspberry pi 4b

I know people have used the UART serial link at 4 Mbps. I2C is limited to about 400 kbps. SPI will probably work at 16 Mbps plus. The maximum will depend on the electrical connections made between the ...
joan's user avatar
  • 71k
1 vote

GPIO configured as interrupts detects noise of the engine even if isolated

In my younger years (long before microprocessors) I spent some time working on automotive electronics. This is a HOSTILE environment - motorcycles are an order of magnitude worse. It is possible BUT ...
Milliways's user avatar
  • 60k
1 vote
Accepted

Transmitting a signal without an external transmitter

It works by generating signal on the GPIO4. You need to connect piece of wire to the pin and it works only in close proximity of few inches. It is for educational, testing purpose rather than for real ...
Qareke's user avatar
  • 153
1 vote

Raspberry pi4 + ADC

This is not a definitive answer because you have not provided the exact code or referenced your hardware. But looking at the data, I see an obvious relation between the timing errors and the ...
Sim Son's user avatar
  • 671
1 vote

Monitor only recognises the signal when started first

Is it because the Pi is defaulting to a low resolution? You can try setting the default resolution (within the configuration) to match the resolution of your monitor. I forget what the default ...
PeteC's user avatar
  • 341
1 vote

Connecting Raspberry Pi 4 to old VGA monitor

As mentioned in the comments, it sure looks like you're using the wrong adapter: VGA-to-HDMI instead of HDMI-to-VGA. So get an appropriate adapter first. I use this one:
Botspot's user avatar
  • 1,769
1 vote

Broadcast VHF or UHF to CRT TV

I think the most simple way is to use the Pi's composite video output and a "Composite to RF modulator" sometimes referred to as "RCA RF modulator" since the composite A/V is using a RCA connector. ...
Ghanima's user avatar
  • 15.9k
1 vote

Generating signals with Pi

I doubt this is practical using PWM. The only method I know of to do the timing would be to use (my) pigpio waveform feature which allows you to switch GPIO on and off for accurately timed periods at ...
joan's user avatar
  • 71k
1 vote

GPIO relay signal cross turns to all relays staying on after Darlington added

In your initial diagram you do not show a GND connection to the module for Relays 6 and 7. Lack of that ground would most likely cause the entire rest of the circuit to misbehave in deterministic ...
SDsolar's user avatar
  • 2,348
1 vote

GPIO relay signal cross turns to all relays staying on after Darlington added

Your pictures don't labelled the connections. Perhaps you can let us know the wires connected to the relay modules. Or you might to confirm if my guess below is correct. I checked your photos and ...
tlfong01's user avatar
  • 4,675
1 vote

GPIO.wait_for_edge and signal.signal()

After changing the doTask function from From: def doTask(): """ A task that will be a daemon """ print "\n" print "Registering handler for:SIGTERM\n" signal.signal(signal.SIGTERM, ...
Pradeep Prakash's user avatar
1 vote

Send and receive 868Mhz signals with my Pi

Any software which works for 434MHz should also work for 868MHz. E.g. my http://abyz.me.uk/rpi/pigpio/examples.html#pdif2__433D may work.
joan's user avatar
  • 71k

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