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#![no_std]
#![no_main]
// Example originally designed for stm32f411ceu6 with three A1454 hall effect sensors, connected to I2C1, 2 and 3
// on the pins referenced in the peripheral definitions.
// Pins and DMA peripherals changed to compile for stm32f429zi, to work with the CI.
// MUST be compiled in release mode to see actual performance, otherwise the async transactions take 2x
// as long to complete as the blocking ones!
use defmt::*;
use embassy_executor::Spawner;
use embassy_stm32::i2c::I2c;
use embassy_stm32::{bind_interrupts, i2c, peripherals};
use embassy_time::Instant;
use futures_util::future::try_join3;
use {defmt_rtt as _, panic_probe as _};
const ADDRESS: u8 = 96;
bind_interrupts!(struct Irqs {
I2C1_EV => i2c::EventInterruptHandler<peripherals::I2C1>;
I2C1_ER => i2c::ErrorInterruptHandler<peripherals::I2C1>;
I2C2_EV => i2c::EventInterruptHandler<peripherals::I2C2>;
I2C2_ER => i2c::ErrorInterruptHandler<peripherals::I2C2>;
I2C3_EV => i2c::EventInterruptHandler<peripherals::I2C3>;
I2C3_ER => i2c::ErrorInterruptHandler<peripherals::I2C3>;
});
/// Convert 12-bit signed integer within a 4 byte long buffer into 16-bit signed integer.
fn a1454_buf_to_i16(buffer: &[u8; 4]) -> i16 {
let lower = buffer[3];
let mut upper = buffer[2];
// Fill in additional 1s if the 12 bit number is negative.
if (upper & 0b00001000) == 0b0001000 {
upper = upper | 0b11110000;
}
let mut sensor_value_raw: u16 = lower.into();
sensor_value_raw |= (upper as u16) << 8;
let sensor_value: u16 = sensor_value_raw.into();
let sensor_value = sensor_value as i16;
sensor_value
}
#[embassy_executor::main]
async fn main(_spawner: Spawner) {
info!("Setting up peripherals.");
let p = embassy_stm32::init(Default::default());
let mut i2c1 = I2c::new(p.I2C1, p.PB8, p.PB7, Irqs, p.DMA1_CH6, p.DMA1_CH0, Default::default());
let mut i2c2 = I2c::new(p.I2C2, p.PB10, p.PB11, Irqs, p.DMA1_CH7, p.DMA1_CH3, Default::default());
let mut i2c3 = I2c::new(p.I2C3, p.PA8, p.PC9, Irqs, p.DMA1_CH4, p.DMA1_CH2, Default::default());
let a1454_read_sensor_command = [0x1F];
let mut i2c1_buffer: [u8; 4] = [0, 0, 0, 0];
let mut i2c2_buffer: [u8; 4] = [0, 0, 0, 0];
let mut i2c3_buffer: [u8; 4] = [0, 0, 0, 0];
loop {
// Blocking reads one after the other. Completes in about 2000us.
let blocking_read_start_us = Instant::now().as_micros();
match i2c1.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c1_buffer) {
Ok(()) => {}
Err(e) => error!("I2C Error: {:?}", e),
}
match i2c2.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c2_buffer) {
Ok(()) => {}
Err(e) => error!("I2C Error: {:?}", e),
}
match i2c3.blocking_write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c3_buffer) {
Ok(()) => {}
Err(e) => error!("I2C Error: {:?}", e),
}
let blocking_read_total_us = Instant::now().as_micros() - blocking_read_start_us;
info!(
"Blocking reads completed in {}us: i2c1: {} i2c2: {} i2c3: {}",
blocking_read_total_us,
a1454_buf_to_i16(&i2c1_buffer),
a1454_buf_to_i16(&i2c2_buffer),
a1454_buf_to_i16(&i2c3_buffer)
);
// Async reads overlapping. Completes in about 1000us.
let async_read_start_us = Instant::now().as_micros();
let i2c1_result = i2c1.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c1_buffer);
let i2c2_result = i2c2.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c2_buffer);
let i2c3_result = i2c3.write_read(ADDRESS, &a1454_read_sensor_command, &mut i2c3_buffer);
// Wait for all three transactions to finish, or any one of them to fail.
match try_join3(i2c1_result, i2c2_result, i2c3_result).await {
Ok(_) => {
let async_read_total_us = Instant::now().as_micros() - async_read_start_us;
info!(
"Async reads completed in {}us: i2c1: {} i2c2: {} i2c3: {}",
async_read_total_us,
a1454_buf_to_i16(&i2c1_buffer),
a1454_buf_to_i16(&i2c2_buffer),
a1454_buf_to_i16(&i2c3_buffer)
);
}
Err(e) => error!("I2C Error during async write-read: {}", e),
};
}
}
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