[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