esp-hal/esp32-hal/examples/spi_loopback.rs

//! SPI loopback test
//!
//! Folowing pins are used:
//! SCLK    GPIO19
//! MISO    GPIO25
//! MOSI    GPIO23
//! CS      GPIO22
//!
//! Depending on your target and the board you are using you have to change the
//! pins.
//!
//! This example transfers data via SPI.
//! Connect MISO and MOSI pins to see the outgoing data is read as incoming
//! data.

#![no_std]
#![no_main]

use esp32_hal::{
    clock::ClockControl,
    gpio::IO,
    peripherals::Peripherals,
    prelude::*,
    spi::{master::Spi, SpiMode},
    Delay,
};
use esp_backtrace as _;
use esp_println::println;

#[entry]
fn main() -> ! {
    let peripherals = Peripherals::take();
    let system = peripherals.SYSTEM.split();
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    let io = IO::new(peripherals.GPIO, peripherals.IO_MUX);
    let sclk = io.pins.gpio19;
    let miso = io.pins.gpio25;
    let mosi = io.pins.gpio23;
    let cs = io.pins.gpio22;

    let mut spi = Spi::new(
        peripherals.SPI2,
        sclk,
        mosi,
        miso,
        cs,
        100u32.kHz(),
        SpiMode::Mode0,
        &clocks,
    );

    let mut delay = Delay::new(&clocks);

    loop {
        let mut data = [0xde, 0xca, 0xfb, 0xad];
        spi.transfer(&mut data).unwrap();
        println!("{:x?}", data);

        delay.delay_ms(250u32);
    }
}