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Cool, so if you just blink 16 times with 16us delays, then wait 5360us and do blinks again - it is Canon remote control code and you can start and stop video recording?

Here is the Blog Post i used for inspration with a graph for the IR Code for both Video and Photo.
https://publiclab.org/notes/cfastie/02-28-2016/auto-eos-m

By the way on usual arduino you probably shouldn't use digitalWrite because it is very slow, if we are talking about microseconds.. direct port manipulation is much better... but maybe your Raspberry Pi Pico is fast enough.

for me it works fine and the author of the blog post corrected for that fact by simply shortening the delays to 11us

You may be better off to use some IR remote control device instead.

I took your advice and build a Device to turn my slate signal into the needed IR Remote Signal.
I also made a Post about it in the Hardware and Accessories section
www.magiclantern.fm/forum/index.php?topic=26557

Hello,
since I was adviced to use a IR remote control device instead of using a lua scipt to start/stop video recording on my EOS M i have build myself such a device.

It takes the Audio Signal from my DR-70D and searches for the slate signal and then uses an IR Led to Start/Stop the recording.

On The DR-70D you need to set the Slate Auto Tone to HEAD+TAIL meaning both at the start and end of the recording there is going to be a slate signal but the camera will only pick up the Tail/end Signal.

Parts needed: Raspberry Pi Pico
                     3.5mm audio jack brakeout board
                     0.1 microF Capacitor
                     940 nm IR Led
First here is the very simple schemetic for this:

And This is the arduino IDE code I came up with:

Code Select Expand

/****************************************
Sketch for a Raspberry Pi Pico based IR
remote Camera starter triggerd by the
slate Signal of a Tascam DR-70D
****************************************/

const int sampleWindow = 500;                   // Sample window width in mS (500 mS = 0.5s)
unsigned int sample;
void setup()
{
  pinMode(0, OUTPUT);                           // Set GP0 as Output
}
void loop()
{
  unsigned long startMillis= millis();          // Start of sample window
  unsigned int peakToPeak;                      // peak-to-peak level
  unsigned int signalMax = 0;
  unsigned int signalMin = 1024;
  while (millis() - startMillis < sampleWindow) // collect data for 500 mS
  {
    sample = analogRead(A0);                    // read from ADC0
    if (sample < 1024)                          // toss out spurious readings
    {
      if (sample > signalMax)
      {
        signalMax = sample;                     // save just the max levels
      }
      else if (sample < signalMin)
      {
        signalMin = sample;                     // save just the min levels
      }
    }
  }
peakToPeak = signalMax - signalMin;             // max - min = peak-peak amplitude

if (peakToPeak < 900 and peakToPeak > 820)      // test for slate Signal
  {
    delay(2000);                                // Wait 2s inorder to not pickup the same slate again
    for(int i=0; i<16; i++)                     // blink IR Led 16 times
    {
      digitalWrite(0, HIGH);
      delayMicroseconds(16);                    // with 16 microseconds on
      digitalWrite(0, LOW);
      delayMicroseconds(16);                    // and 16 microseconds off time
    }
    delayMicroseconds(5360);                    // Off Period of 5360 microseconds
    for(int i=0; i<16; i++)                     // blink IR Led 16 times
    {
      digitalWrite(0, HIGH); 
      delayMicroseconds(16);                    // with 16 microseconds on
      digitalWrite(0, LOW);
      delayMicroseconds(16);                    // and 16 microseconds off time
    }
  }
}

I think i didnt Marke it clear enough.
I do know how to sync my camera and sound.
What i want is to Start multiple cameras with sound because i recorde a stage and want to have every angle covert from the Start of the performance which is why i cant walk around to start every camera.

I have a EOS M and a Tascam DR-70D Audio Recorder whitch has a slate function aka a loud beep to better sync audio in post.

My qustion now is could i use that loud sound in order to automaticly start and stop the recording?

Why do i want to do this?
I have multiple cameras that are circled around what i am filming and i would like to use wireless audio to start/stop the cameras simoultaniosly.