Pico Arduino DS18B20 OneWire

Question

I am failing to read a DS18B20 with a RaspberryPi Pico programmed with Arduino.

I found several examples using MicroPython, however I want to do it with Arduino using the 'Raspberry Pi Pico/RP2040' plugin by Earle F. Philhower.

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

#define ONE_WIRE_BUS 14

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

void setup() 
{
  Serial.begin(115200);
}

void loop() 
{
  DS18B20.requestTemperatures();
  float temp = DS18B20.getTempCByIndex(0);
  Serial.print("Temperature: ");
  Serial.println(temp);

  delay(2000);
}

The code compiles, but leaves a warning

#warning "OneWire. Fallback mode. Using API calls for pinMode, digitalRead and digitalWrite. Operation of this library is not guaranteed on this architecture."

On the pico nothing works. Since not even the virtual com port appears, I assume the code fails before starting the loop.

I have tried different ports and also different versions of the code. Nothing works. Can anybody provide an example?

Answer 1

This is not an answer, this is only FWIW:

I've successfully used the "Philhower plugin for Arduino" on a couple of small projects, and it worked fine. However my devices used i2c - not "OneWire"; i.e. the device libraries I used were written for i2c.

I understand how i2c works, but I am quite ignorant on "OneWire" as I've never had to use it. I have heard that it's quite different from i2c, but I can neither support nor rebut that claim. The warning you got suggests that perhaps Philhower has added some code to his library to implement "OneWire", but that it may not be "ready for prime time". You should probably take the warning seriously.

Wrt "... not even the virtual com port appears", you should try another (simple) project to verify you have your environment set up properly.

A couple of things to ponder: If your DS18B20 has a library based on i2c, you should consider trying that. If not, drive on with "OneWire", and go to Philhower's GitHub repo to submit an issue or engage in discussion.