1-wire

Allows using 1-wire devices such as digital thermometers (i.e. MAX31820, DS18B20). See sample for how to use.

Documentation

• dtoverlay

Board

The following diagram demonstrates how you should wire your device in order to run the program. It uses the GND, 5V and GPIO4 pins on the Raspberry Pi.

Usage

using System;
using System.Linq;
using System.Threading.Tasks;
using Iot.Device.OneWire;

// Make sure you can access the bus device before requesting a device scan (or run using sudo)
// $ sudo chmod a+rw /sys/bus/w1/devices/w1_bus_master1/w1_master_*
if (args.Any(_ => _ == "temp"))
{
    // Quick and simple way to find a thermometer and print the temperature
    foreach (var dev in OneWireThermometerDevice.EnumerateDevices())
    {
        Console.WriteLine($"Temperature reported by '{dev.DeviceId}': " +
                            (await dev.ReadTemperatureAsync()).DegreesCelsius.ToString("F2") + "\u00B0C");
    }
}
else
{
    // More advanced way, with rescanning the bus and iterating devices per 1-wire bus
    foreach (string busId in OneWireBus.EnumerateBusIds())
    {
        OneWireBus bus = new(busId);
        Console.WriteLine($"Found bus '{bus.BusId}', scanning for devices ...");
        await bus.ScanForDeviceChangesAsync();
        foreach (string devId in bus.EnumerateDeviceIds())
        {
            OneWireDevice dev = new(busId, devId);
            Console.WriteLine($"Found family '{dev.Family}' device '{dev.DeviceId}' on '{bus.BusId}'");
            if (OneWireThermometerDevice.IsCompatible(busId, devId))
            {
                OneWireThermometerDevice devTemp = new(busId, devId);
                Console.WriteLine("Temperature reported by device: " +
                                    (await devTemp.ReadTemperatureAsync()).DegreesCelsius.ToString("F2") +
                                    "\u00B0C");
            }
        }
    }
}

How to setup 1-wire on Raspberry Pi

Add the following to /boot/firmware/config.txt to enable 1-wire protocol. The default gpio is 4 (pin 7).

dtoverlay=w1-gpio

Add this to specify gpio 17 (pin 11).

dtoverlay=w1-gpio,gpiopin=17

Supported devices

All temperature devices with family id of 0x10, 0x28, 0x3B, or 0x42 supported.

• MAX31820
• DS18B20