I2C multiple devices #478

Fristi · 2023-04-13T13:27:02Z

Fristi
Apr 13, 2023

Hi,

I would like to read a sensor and afterwards display it's readings on a display.

All the devices are connected on one I2C bus, thus;

let i2c = I2C::new(
        peripherals.I2C0,
        io.pins.gpio21,
        io.pins.gpio22,
        20u32.kHz(),
        &mut system.peripheral_clock_control,
        &clocks,
    );

This can be passed in for example a SSD1306 display interface, but when you want to read a sensor you'll need i2c again, but Rust forbids this.

I tried to work around this with

pub struct I2cShare<'a, T> {
    i2c_bit: &'a mut I2C<'a, T>,
}

impl<'a, T> I2cShare<'a, T> {
    pub fn new(i2c_bit: &'a mut I2C<'a, T>) -> Self {
        Self { i2c_bit }
    }
}

impl<'a, T> Write for I2cShare<'a, T> where T : Instance {
    type Error = Error;

    fn write(&mut self, address: SevenBitAddress, bytes: &[u8]) -> Result<(), Self::Error> {
        self.i2c_bit.write(address, bytes)
    }
}

impl<'a, T> Read for I2cShare<'a, T> where T : Instance {
    type Error = Error;

    fn read(&mut self, address: SevenBitAddress, buffer: &mut [u8]) -> Result<(), Self::Error> {
        self.i2c_bit.read(address, buffer)
    }
}