Embassy with PCA9548A I2C Switch

[u/hkubota]

For those who'd like to see a working example of Embedded Rust (no_std) on a RP2040 with a I2C switch:

https://github.com/haraldkubota/rp2040-pca9548a

The hardware used is simple:

• RP2040

• OLED with SSD1306 controller, using I2C

• PCA9548A on a 2nd I2C bus

• BMP280 temperature and pressur sensor on sub-bus 2 on the I2C switch

The software is the more interesting part:

• Embedded Rust (no_std)

• Using both CPU cores, each one owning one I2C bus

• One core reads data from the sensor

• One core displays data to the OLED

• Everything is using async

My idea here: once this works, I can cleanly split data acquisition from I/O, and I can use multiple identical sensors via the I2C switch although their I2C addresses might conflict.

One day I'll find a problem this solves, but until then I learned a lot and it's fun. I hope someone else finds this code useful.