I2C Temperature Sample

This sample project contains a driver component named i2c_temperature for a temperature sensor device connected to an I2C bus with device address 0xFF. The driver interacts with the device hardware using the fuchsia.hardware.i2c protocol, and exposes a custom FIDL protocol (examples.i2c.temperature) for other components to consume.

The i2c_controller driver component emulates an I2C bus controller, creating the child device nodes to the sensor device and responding to I2C protocol commands received from the child devices.

Building

To build the i2c_temperature driver and related components, run the following commands:

tools/bazel build --config=fuchsia_x64 //src/i2c_temperature/controller:pkg
tools/bazel build --config=fuchsia_x64 //src/i2c_temperature/driver:pkg

Running

Use the following commands to load the driver components on a target device:

1. Add a test node for the i2c_controller driver:

   tools/ffx driver test-node add controller-node \
     examples.driver.test.property=i2c-temperature-controller
   

2. Load the i2c_controller driver component to create a virtual I2C device node:

   tools/bazel run //src/i2c_temperature/controller:pkg.component
   

3. Load the i2c_temperature driver component to bind to the device node and begin sending requests:

   tools/bazel run //src/i2c_temperature/driver:pkg.component
   

4. Open the device log viewer:

   tools/ffx log --tags i2c-temperature --tags i2c-temperature-controller
   

You should see the i2c_controller driver log the requests it receives from i2c_temperature after the driver has successfully bound.

[i2c-temperature-controller,driver][I]: [i2c_controller.cc:139] Received transfer request
[i2c-temperature-controller,driver][I]: [i2c_controller.cc:126] Reset command received

Driver client

After the drivers are loaded, use the following commands to run the temperature client:

1. Load the temperature_client component:

   tools/bazel run --config=fuchsia_x64 //src/i2c_temperature/client:pkg.component
   

2. Open the device log viewer:

   tools/ffx log --filter temperature_client
   

You should see the client respond with an incrementing temperature value on each run:

[ffx-laboratory:temperature_client][I] Current temperature: 25.000000

Source layout

• controller/ — Source code of the i2c_controller driver component.
• driver/ — Source code of the i2c_temperature driver component.
• fidl/ — FIDL library definition for examples.i2c.temperature.
• lib/ — Common I2C constants shared between the controller and driver components.