Trait kernel::hil::spi::SpiMaster [−] [src]

pub trait SpiMaster {
    type ChipSelect: Copy;
    fn set_client(&self, client: &'static SpiMasterClient);

    fn init(&self);

    fn is_busy(&self) -> bool;

    fn read_write_bytes(
        &self, 
        write_buffer: &'static mut [u8], 
        read_buffer: Option<&'static mut [u8]>, 
        len: usize
    ) -> ReturnCode;

    fn write_byte(&self, val: u8);

    fn read_byte(&self) -> u8;

    fn read_write_byte(&self, val: u8) -> u8;

    fn specify_chip_select(&self, cs: Self::ChipSelect);

    fn set_rate(&self, rate: u32) -> u32;

    fn get_rate(&self) -> u32;

    fn set_clock(&self, polarity: ClockPolarity);

    fn get_clock(&self) -> ClockPolarity;

    fn set_phase(&self, phase: ClockPhase);

    fn get_phase(&self) -> ClockPhase;

    fn hold_low(&self);

    fn release_low(&self);
}

The SpiMaster trait for interacting with SPI slave devices at a byte or buffer level.

Using SpiMaster normally involves three steps:

  1. Configure the SPI bus for a peripheral 1a. Call set_chip_select to select which peripheral and turn on SPI 1b. Call set operations as needed to configure bus NOTE: You MUST select the chip select BEFORE configuring SPI settings.
  2. Invoke read, write, read_write on SpiMaster 3a. Call clear_chip_select to turn off bus, or 3b. Call set_chip_select to choose another peripheral, go to step 1b or 2.

This interface assumes that the SPI configuration for a particular peripheral persists across chip select. For example, with this set of calls:

specify_chip_select(1); set_phase(SampleLeading); specify_chip_select(2); set_phase(SampleTrailing); specify_chip_select(1); write_byte(0); // Uses SampleLeading

If additional chip selects are needed, they can be performed with GPIO and manual re-initialization of settings.

specify_chip_select(0); set_phase(SampleLeading); pin_a.set(); write_byte(0xaa); // Uses SampleLeading pin_a.clear(); set_phase(SampleTrailing); pin_b.set(); write_byte(0xaa); // Uses SampleTrailing

Associated Types

Required Methods

Perform an asynchronous read/write operation, whose completion is signaled by invoking SpiMasterClient on the initialized client. write_buffer must be Some, read_buffer may be None. If read_buffer is Some, the length of the operation is the minimum of the size of the two buffers.

Tell the SPI peripheral what to use as a chip select pin. The type of the argument is based on what makes sense for the peripheral when this trait is implemented.

Returns the actual rate set

Implementors