I am using the analogue input with the M5Stamp S3, but GPIO3 is constantly outputting 4095.
Other outputs give the correct values.
I use Arduino IDE 2.3.3, and the code is
void setup() {
  Serial.begin(115200); 
  for(int i=1;i<=15;i++){
      pinMode(i,ANALOG);
  }
}
void loop() {
    
   int index = 0; 
  for (int pin = 1; pin <= 15; pin++) {
    v[index] = analogReadMilliVolts(pin); 
    Serial.print(String(v[index]));
    if (index < 13) { 
      Serial.print(",");
    }
    index++; 
  }
  Serial.println(); 
  delay(1000);
    
}