I2C bus sharing

Before we dive into writing our IMU driver, we need to address some issues.

Sharing the I2C bus

In the current setup, the touch panel driver is given an exclusive access to the I2C peripheral. Our IMU is also on the I2C bus, so we have to share the peripheral between the two device drivers.

As explained in the embedded-hal crate documentation, we can use the embedded-hal-bus for this. The crate provides several types of abstractions for bus sharing, but since we're working in a single-threaded application, a RefCell will be sufficient.

Let's start by importing the necessary types.

#![allow(unused)]
fn main() {
use core::cell::RefCell;
use embedded_hal_bus::i2c::RefCellDevice;
}

Then, right after i2c object instantiation, wrap the original object:

#![allow(unused)]
fn main() {
let i2c = RefCell::new(i2c);
}

Finally, in the instantiation of the touch driver, instead of passing i2c directly, create a new shared instance:

#![allow(unused)]
fn main() {
let mut touch_driver = axs5106l::Axs5106l::new(
    RefCellDevice::new(&i2c),
    ...
}

The code should compile and run just as before, give it a try.