Nonblocking implementation

[ost-ing]

• MCU/other hardware in use: STM32h7
• Display resolution and interface: I2C, [128x64]

Nonblocking I2C support

Hello, I'm attempting to build an application that utilizes this library in conjunction with doing real-time DAC/ADC functions. I have noticed that my DAC output, which is executed from a Timer producing a simple sine-wave is blocked by the I2C communication that this library executes, which distorts the output of the DAC.

I know that the embedded-hal doesn't support non-blocking for various reasons. What I would like to do is write my own interface adapter and implement I2C interrupt handling within my app to unblock the communication to the display.

Looking at the test_helpers.rs, I see this:

#[allow(dead_code)]
#[derive(Debug, Clone, Copy)]
pub struct StubInterface;

impl WriteOnlyDataCommand for StubInterface {
    fn send_commands(
        &mut self,
        _cmd: display_interface::DataFormat<'_>,
    ) -> Result<(), DisplayError> {
        Ok(())
    }
    fn send_data(&mut self, _buf: display_interface::DataFormat<'_>) -> Result<(), DisplayError> {
        Ok(())
    }
}

I assume that I could use the WriteOnlyDataCommand trait to achieve this?

Kind regards Oliver

[jamwaffles]

Sorry for the delay! @therealprof maintains the crate that WriteOnlyDataCommand so might be able to offer more insight, but yes I think it's enough to add a custom impl of WriteOnlyDataCommand and pass that into Builder::new().connect(interface).into() instead of the provided blocking implementations.

[quentinmit]

There's an embedded-hal-async now that provides async/await-compatible bus interfaces. See https://github.com/jamwaffles/ssd1331/pull/13 for a PR adding support to the ssd1311 crate and follow https://github.com/embedded-graphics/embedded-graphics/issues/622 for an upstream embedded-graphics trait.

It looks like someone already has an async fork: https://github.com/simmsb/ssd1306

[bugadani]

cc https://github.com/jamwaffles/ssd1306/pull/178