esp-hal/esp32s2-hal/examples/spi_loopback.rs

//! SPI loopback test
//!
//! Folowing pins are used:
//! SCLK    GPIO36
//! MISO    GPIO37
//! MOSI    GPIO35
//! CS      GPIO34
//!
//! 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 esp32s2_hal::{
    clock::ClockControl,
    gpio::IO,
    peripherals::Peripherals,
    prelude::*,
    spi::{Spi, SpiMode},
    timer::TimerGroup,
    Delay,
    Rtc,
};
use esp_backtrace as _;
use esp_println::println;

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

    // Disable the watchdog timers. For the ESP32-S2, this includes the RTC WDT, and
    // the TIMG WDT.
    let mut rtc = Rtc::new(peripherals.RTC_CNTL);
    let timer_group0 = TimerGroup::new(
        peripherals.TIMG0,
        &clocks,
        &mut system.peripheral_clock_control,
    );
    let mut wdt = timer_group0.wdt;

    wdt.disable();
    rtc.rwdt.disable();

    let io = IO::new(peripherals.GPIO, peripherals.IO_MUX);
    let sclk = io.pins.gpio36;
    let miso = io.pins.gpio37;
    let mosi = io.pins.gpio35;
    let cs = io.pins.gpio34;

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