[BUG] analogRead(35) beeps

daslolo

That's uncommon.
Try this out:

#include <M5Stack.h>

void setup() {
M5.begin();
}

void loop() {
float v = analogRead(35);
}

daslolo

So the DSOs have voltage dividers not voltage regulators?
Good to know about noise causing spikes like that. I read that 3.3V on the EPS input is the maximum and more could damage the chip, ouch. How do I know if I damaged my esp32?

@calin 在 M5Stack 2 Channel Oscilloscope 中说：

Some basic filters and voltage dividers at the input pin, can solve that problem.

I'm familiar with voltage divider but what are examples of basic filters?

Calin

add dacWrite(25,0); after M5.begin(); and the noise will be gone.

daslolo

@calin thank you, this did it.
Could you explain what was happening and why dacWrite(25,0) is working?

dda

@daslolo #define SPEAKER_PIN 25 --> src/utility/Config.h

void SPEAKER::mute() {
  ledcWriteTone(TONE_PIN_CHANNEL, 0);
  digitalWrite(SPEAKER_PIN, 0);
}

--> src/utility/Speaker.cpp

Basically, it's telling the M5 speaker to shut up.

JJ

@dda So it is the "shut up"function ! ha ha