Add dacWrite (25,0); into the void loop

I checked that the pin "works" correctly by connecting a relay to test in OUTPUT mode, and a push button (to test in INPUT) : it works!
I checked, double checked and triple checked the setup (wires, connections,...), everything is good.
I ran the same code on a Wemos D1 Mini (ESP8266) : it works.

At this point, I'm lost? The pin and the code seem good, but it can't detect the sensor.

One thing I notice is that this weird whistling sound coming out of the board (not sure if it comes from the speaker or not) when the OneWire lib bitbangs the OneWire protocol on the pin.
So, I made another test program that toggles the pin rapidely (at the speed of the onewire lib - ~50µs) : I hear the sound!

I'll try to find an oscilloscope to check the signal on the pin, as I suspect that "something" is going wrong when the pin is driven at "high" speed.

In the meantime, I hope that someone with more electronical knowledge will help me find a solution!

OneWire version 2.3.4
DallasTemperature version 3.79

Thanks, @zazar!

I use exactly the same lib, and similar code without any result for now, unfortunately.

	#include <M5Stack.h>
	#include <OneWire.h>
	#include <DallasTemperature.h>

	#define ONE_WIRE_BUS 5  // DS18B20 on arduino pin2 corresponds to D4 on physical board

	OneWire oneWire(ONE_WIRE_BUS);
	DallasTemperature DS18B20(&oneWire);

	void setup() {
	  M5.begin();
	  M5.Lcd.setTextColor(TFT_WHITE,TFT_BLACK);  
	  M5.Lcd.setTextSize(2);

	}

	void loop() {
	  float celsius;
	  float fahrenheit;

	  DS18B20.begin();
	  int count = DS18B20.getDS18Count();

	  //M5.Lcd.clear();
	  M5.Lcd.setCursor(0,0);
	  M5.Lcd.print("Devices found: ");
	  M5.Lcd.println(count);

	  if (count > 0) {

		DS18B20.requestTemperatures();

		for (int i=0; i < count; i++) {

		  celsius = DS18B20.getTempCByIndex(i);
		  fahrenheit = celsius * 1.8 + 32.0;
  
		  celsius = round(celsius);
		  fahrenheit = round(fahrenheit);
  
		  M5.Lcd.print("Device ");
		  M5.Lcd.print(i);
		  M5.Lcd.print(": ");
		  M5.Lcd.print(celsius,0);
		  M5.Lcd.print( "C / ");
		  M5.Lcd.print(fahrenheit,0);
		  M5.Lcd.println("F");
  
		}

	  }

	  delay(2000);
	}

Is there something I'm missing, or is there an hardware issue with my board?

Try it.
GPIO2 fully free
https://github.com/G6EJD/ESP32-DS18B20-Sensor-Reading

I've already tried, and I can't find why it doesn't work, that's why I'm asking.

I've tried your example, I've just set the define ONE_WIRE_BUS to 2:

#define ONE_WIRE_BUS 2 

The sensor is still not detected. Moreover, the board make a little piercing sound when it probes for the sensor and the temperature. I don't understand where it comes from, as GPIO2 should not be connected to the speaker...

Any ideas?

@zazar has already done it.

http://forum.m5stack.com/topic/95/custom-prototype-board/11

@zazar, if you come by, could you provide us with some information about your project? How did you connect the DS18B20 sensors (wich pins did you use)? Which Onewire/ds18b20 lib did you use, if any ?

Thanks!

http://forum.m5stack.com/topic/95/custom-prototype-board/11