Strange delay with analogWrite on XIAO ESP32-C3 vs. XIAO SAMD21

Products & Technology XIAO
#1

I’ve encountered strange behaviour where there’s siginificant 1-2 second delay between running analogwrite and having that new value actually be outputted from the pin.

I reduced the problem on very simple test that works as it should on XIAO SAMD21 but when uploaded to ESP32-C3 it causes 1-2 seconds delay between the input pin getting high and the output reflecting the change. If I change the analogWrite to digitalWrite the delay is gone and output reflects the input instantaneously on ESP32-C3 also.

Any thought’s what is going on here?

test sketch

int _m1Output = 5;
int _m1ScaledSpeed = 0;

void setup() {
Serial.begin(115200);
pinMode(_m1Output, OUTPUT);
pinMode(2, INPUT);
}

void loop() {
_m1ScaledSpeed = map(digitalRead(2), 0, 1, 0, 255);
Serial.println(_m1ScaledSpeed);
analogWrite(_m1Output, _m1ScaledSpeed);
}

#2

Here’s short video clip running the code above (with different max out value).

video clip

#3

What do you expect from analogWrite() on the XIAO ESP32C3?
It cannot provide analog voltage output because it does not have a built-in DAC.
For PWM output, please see the following instead of analogWrite().
//\Arduino15\packages\esp32\hardware\esp32\2.0.6\cores\esp32\esp32-hal-ledc.c and .h

edit:
I have confirmed that the following code works, needed delay() in the loop. I do not know why.

int pwm = 0;
void setup() {
  Serial.begin(115200);

  pinMode(D10, OUTPUT);
  pinMode(D1, INPUT_PULLUP);
}

void loop() {
  pwm = map(digitalRead(D1), 0, 1, 0, 255);
  Serial.println(pwm);
  analogWrite(D10, pwm);
  delay(100);  // needed
}
#4

Thank you so much looking into this! I can also confirm that just adding delay even as short as 1ms makes this work on ESP32-C3.

I’m quite curious what’s going on here and why the delay makes the difference o ESP32-C3 vs. XIAO SAMD21.

Anyways, thanks for your help @msfujino