embassy/examples/nrf52840/src/bin/twim_lowpower.rs

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//! Example on how to read a 24C/24LC i2c eeprom with low power consumption.
//! The eeprom is read every 1 second, while ensuring lowest possible power while
//! sleeping between reads.
//!
//! Connect SDA to P0.03, SCL to P0.04
#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]
use core::mem;
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use defmt::*;
use embassy_executor::Spawner;
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use embassy_nrf::twim::{self, Twim};
use embassy_nrf::{bind_interrupts, peripherals};
use embassy_time::{Duration, Timer};
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use {defmt_rtt as _, panic_probe as _};
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const ADDRESS: u8 = 0x50;
bind_interrupts!(struct Irqs {
SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0 => twim::InterruptHandler<peripherals::TWISPI0>;
});
#[embassy_executor::main]
async fn main(_p: Spawner) {
let mut p = embassy_nrf::init(Default::default());
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info!("Started!");
loop {
info!("Initializing TWI...");
let config = twim::Config::default();
// Create the TWIM instance with borrowed singletons, so they're not consumed.
let mut twi = Twim::new(&mut p.TWISPI0, Irqs, &mut p.P0_03, &mut p.P0_04, config);
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info!("Reading...");
let mut buf = [0u8; 16];
unwrap!(twi.blocking_write_read(ADDRESS, &mut [0x00], &mut buf));
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info!("Read: {=[u8]:x}", buf);
// Drop the TWIM instance. This disables the peripehral and deconfigures the pins.
// This clears the borrow on the singletons, so they can now be used again.
mem::drop(twi);
// Sleep for 1 second. The executor ensures the core sleeps with a WFE when it has nothing to do.
// During this sleep, the nRF chip should only use ~3uA
Timer::after(Duration::from_secs(1)).await;
}
}