Uploaded February 2026 | Updated September 2026, 2 weeks ago

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This tutorial covers how to use Inter-Integrated Circuit (I2C) communication in embedded Rust on the Raspberry Pi Pico 2. I2C is one of the most widely used protocols in embedded systems, enabling microcontrollers to communicate with sensors, displays, memory chips, and countless other peripherals using just two wires. We'll build on our USB serial template to create a temperature monitoring application that reads data from a TMP102 I2C sensor and displays it over USB serial when you press a button.
The written guide for this episode can be found here: digikey.com/en/maker/tutorials/2026/intro-to-embedded-rust-part-5-reading-from-an-i2c-temperature-sensor
The GitHub repository containing the Docker image and example code for this series can be found here: github.com/ShawnHymel/introduction-to-embedded-rust
We’ll explore how to configure GPIO pins for their alternate I2C functions using the rp235x-hal, initialize the I2C peripheral with the proper clock speed (100 kHz standard mode), and perform write-read operations to communicate with I2C devices. We explain I2C addressing and how to access device registers. The tutorial walks through reading the TMP102's datasheet to understand its register layout, performing combined write-read transactions, and converting raw binary sensor data into meaningful temperature values in degrees Celsius. You'll see practical bit manipulation techniques including shifting and masking to extract 12-bit signed temperature values from the sensor's two-byte response.
The project also introduces important embedded Rust patterns beyond just I2C. We demonstrate button input handling with pull-up resistors and implementing edge detection to trigger readings only on button press. You'll see how to use the heapless crate to work with fixed-size strings without heap allocation (essential for no-std embedded development where heap usage is often avoided). We show how to format floating-point temperature values into strings using the write! macro and core::fmt::Write trait, providing formatted output without the standard library. The tutorial also covers practical error handling for I2C operations using Rust's Result type, showing how to gracefully handle communication failures and display error messages over USB serial.
The demo used in this tutorial provides a reusable template for interfacing with I2C devices that you can adapt for accelerometers, gyroscopes, displays, EEPROMs, and thousands of other I2C peripherals.

Related Link:
digikey.com/en/maker/tutorials/2026/intro-to-embedded-rust-part-5-reading-from-an-i2c-temperature-sensor

Links:
Getting Started with STM32 and Nucleo: youtube.com/watch?v=hyZS2p1tW-g&list=PLEBQazB0HUyRYuzfi4clXsKUSgorErmBv
Introduction to Real-Time Operating Systems (RTOS): youtube.com/watch?v=F321087yYy4&list=PLEBQazB0HUyQ4hAPU1cJED6t3DU0h34bz
Raspberry Pi Pico 2: digikey.com/en/products/detail/raspberry-pi/SC1631/24627142

Learn more:
Maker.io - digikey.com/en/maker
DigiKey’s Blog – TheCircuit digikey.com/en/blog
Connect with DigiKey on Facebook facebook.com/digikey.electronics
And follow us on X: https://x.com/digikey

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Chapters:
0:00 Intro
0:45 Overview of TMP102 Temperature Sensor
3:14 Dependencies
4:00 Initialize Input Pin and I2C
13:11 Read and Print Temperature Value on Button Press
23:44 Build and Flash
25:24 Challenge and Reading Assignment
26:18 Conclusion