DS18x20 Pico MQTT

An MQTT client for the Pico W that publishes DS18x20 temperature readings in a Home Assistant-friendly format.

Features

• Support for the Raspberry Pi Pico W.
• Publishes temperature readings from a DS18x20 sensor in a Home Assistant-friendly format at a rate of 1Hz.

Getting Started (Hardware)

TODO(Jon). Some nice pics of the ginished product, and the wiring diagram would be nice.

Getting Started (Software)

Ensure Git submodules are resolved.

git submodule update --recursive --init

Install build-time dependencies.

apt-get install -y cmake python3 gcc-arm-none-eabi g++

Building

Run the following to build the project, ensuring you update the config options to suit your setup.

mkdir build
cd build
cmake \
  -DPICO_SDK_PATH="modules/pico-sdk" \
  -DWIFI_SSID="network ssid" \
  -DWIFI_PASSWORD="network password" \
  -DMQTT_BROKER_ADDRESS="192.168.1.2" \
  -DMQTT_BROKER_PORT=1883 \
  -DDEVICE_NAME="Pico DS18x20 Temperature Probe" \
  -DHA_MQTT_PREFIX="homeassistant" \
  -DGPIO_PIN=17 \
  ..
cmake --build .

The binaries will now be available in the /build directory!

Running

To run the project, copy the built ds18x20-pico-mqtt.uf2 (in the /build directory) binary over to your Pico; ensure your Pico is in USB Mass Storage mode by holding the BOOTSEL button when powering up.

The Pico will run the binary once it restarts.

Debugging

You can use USB Serial (minicom) to view the standard output of the app running on the Pico. Run minicom -b 115200 -o -D /dev/ttyACM0 from the host that the Pico is connected to and you should start seeing the logs. Note, minicom must be installed for this to work (apt-get install -y minicom).

VS Code Dev Container

There are pre-configured .devcontainer and .vscode directories committed to this repo which should make setting up the development environment really easy.

Note: when building the Dev Container, your Pico must be connected! This is because the /dev/ttyACM0 device is forwarded to the container - so creating the container will fail if its unreachable.

Config options that the CMake build task needs access to are defined in the .env.sh.example file. Duplicate that file with the new name env.sh and enter your config within and it should be used by the built binaries from then onwards.

Run the VS Code build command (ctrl+shift+b) or run the "Build" custom task. The binaries will now be available in the /build directory. You can copy the built binary over to the Pico in the same way as mentioned above.

You can also run the task "Monitor Pico's USB serial output" to monitor the standard output of the Pico when its running (and connected!).

Changelog

See CHANGELOG.md.