std/spi — SPI master

import std/spi

Blocking master-mode SPI. The module configures the hardware SPI peripheral as a master and exchanges single bytes, busy-waiting on the transfer-complete flag.

SPI0

@spi_init_master_raw()

Initialise the SPI peripheral in master mode with a default configuration (“raw”: no chip-select management or mode/clock options beyond enabling master mode). Drive any chip-select line yourself with the GPIO module.

@spi_transfer($data: u8) -> u8

Shift $data out over MOSI while simultaneously shifting a byte in over MISO; block until the exchange completes and return the received byte. SPI is full-duplex, so every transfer both sends and receives.

Additional SPI instance

Devices with a second SPI peripheral expose the same two calls on the spi1 module:

• @spi1_init_master_raw()

• @spi1_transfer($data: u8) -> u8

Example

target atmega328p
import std/spi
import std/gpio

@main {
    @pin_mode_b(2, 1)              # PB2 = chip-select line, configured as output
    @spi_init_master_raw()         # bring SPI up in master mode

    @digital_write_b(2, 0)         # pull CS low to select the slave
    # 0x9F is a device-specific command (here a common "read ID"); the value
    # to send comes from your slave's datasheet, not from SPI itself.
    ram imut $resp: u8 = @spi_transfer(0x9F)   # send the byte, capture the reply
    @digital_write_b(2, 1)         # raise CS to deselect
}