Embedded Rust on Espressif

I²C Sensor Reading Exercise

In this exercise, you will learn how to read out sensors on the I²C bus.

The Rust ESP Board has two sensors that can be read via the I²C bus:

The task is to use an existing driver from crates.io to read out the temperature and humidity sensor over I²C. After that, a second sensor will be read out over the same I²C bus using shared-bus.

Part 1: Reading Temperature & Humidity

Create an instance of the Humidity sensor SHTC3 and read and print the values for humidity and temperature every 600 ms.

i2c-sensor-reading/examples/part_1.rs contains a working solution of Part 1. To run the solution for Part 1:

cargo run --example part_1

i2c-sensor-reading/src/main.rs contains skeleton code, that already contains necessary imports for this part.

Steps:

✅ Go to the i2c-sensor-reading/ folder and open the relevant documentation with the following command:

cargo doc --open

✅ Define two pins, one as SDA and one as SCL.

✅ Create an instance of the I²C peripheral with the help of the documentation you generated. Use 400 kHz as frequency.

✅ Use the shtcx driver crate, make an instance of the SHTC3 sensor, passing the I²C instance into them. Check the documentation for guidance.

✅ To check if the sensor is addressed correctly, read its device ID and print the value.

Expected Output:

Device ID SHTC3: 71

✅ Make a measurement, read the sensor values and print them. Check the documentation for guidance on sensor methods.

Expected Output:

TEMP: [local temperature] °C
HUM: [local humidity] %

❗ Some sensors need some time to pass between measurement and reading value. ❗ Watch out for the expected units!

💡 There are methods that turn the sensor values into the desired unit.

Part 2: Reading Accelerometer Data

Using a bus manager, implement the second sensor. Read out its values and print the values from both sensors.

Continue with your own solution from part one. Alternatively, you can start with the provided partial solution of Part 1: i2c-sensor-reading/examples/part_1.rs.

i2c-sensor-reading/examples/part_2.rs contains a working solution of Part 2. You can consult it if you need help, by running:

cargo run --example part_2

Steps

✅ Import the driver crate for the ICM42670p.

#![allow(unused)]
fn main() {
use icm42670::{Address, Icm42670, PowerMode as imuPowerMode};
}

✅ Create an instance of the sensor.

✅ Why does passing the same I²C instance to two sensors not work, despite both being on the same I²C bus?

✅ Import the bus manager crate.

#![allow(unused)]
fn main() {
use shared_bus::BusManagerSimple;
}

✅ Create an instance of a simple bus manager. Make two proxies and use them instead of the original I²C instance to pass to the sensors.

✅ Read & print the device ID from both sensors.

Expected Output:

Device ID SHTC3: 71
Device ID ICM42670p: 96

✅ Start the ICM42670p in low noise mode.

✅ Read the gyroscope sensor values and print them with 2 decimal places alongside the temperature and humidity values.

Expected Output:

GYRO: X: 0.00 Y: 0.00 Z: 0:00
TEMP: [local temperature] °C
HUM: [local humidity] %

Simulation

This project is available for simulation through two methods:

• Wokwi projects
  • Exercise
  • Solution Part 2
• Wokwi files are also present in the project folder to simulate it with Wokwi VS Code extension:
  1. Press F1, select Wokwi: Select Config File and choose advanced/i2c-sensor-reading/wokwi.toml
     • Edit the wokwi.toml file to select between exercise and solutions simulation
  2. Build you project
  3. Press F1 again and select Wokwi: Start Simulator

When simulating this project, expect the following hardcoded values: TEMP: 24.61 °C | HUM: 36.65 % | GYRO: X= 0.00 Y= 0.00 Z= 0.00