[15-led-compass] LSM303AGR board version aux15::init() not working?

[dcabanis]

Hi all,

I am running the lab 15 with a DISCOVERY board bought in 2021. it has the LSM303AGR eCompass chip on it as opposed to the original board's LSM303DLHC.

As I am building the starter code and the solution code, all passes without any errors but when I try to run the examples the X, Y, Z are always set to 0.

I have the feeling that the aux15::init() function isn't properly initializing the device. Is anyone encountering the same issue with the latest board?

Cheers.

[eisnstein]

As it states in 14.2, you have to check out this issue regarding the LSM303AGR #274. I also just started with 15 and so far I got the very first example running.

1. add lsm303agr = "0.1" to the dependencies in your 15-led-compass/auxiliary/Cargo.toml so that it looks like this:

[package]
authors = ["Jorge Aparicio <[email protected]>"]
edition = "2018"
name = "aux15"
version = "0.1.0"

[dependencies]
cortex-m = "=0.5.6"
cortex-m-rt = "0.6.3"
panic-itm = "=0.4.0"
lsm303agr = "0.1"

[dependencies.f3]
features = ["rt"]
version = "0.6.1"

2. Change the 15-led-compass/auxiliary/src/lib.rs to use the lsm303agr instead of the lsm303dlhc:

//! Initialization code

#![no_std]

#[allow(unused_extern_crates)] // NOTE(allow) bug rust-lang/rust#53964
extern crate panic_itm; // panic handler

pub use cortex_m::{asm::bkpt, iprint, iprintln, peripheral::ITM};
pub use cortex_m_rt::entry;
pub use f3::{
    hal::{
        delay::Delay, gpio::gpiob::PB6, gpio::gpiob::PB7, gpio::AF4, prelude, stm32f30x::i2c1,
        stm32f30x::I2C1,
    },
    led::{Direction, Leds},
    lsm303dlhc::I16x3,
};
pub use lsm303agr::{ UnscaledMeasurement };

use f3::{
    hal::{i2c::I2c, prelude::*, stm32f30x},
    Lsm303dlhc,
};

use lsm303agr::{interface::I2cInterface, mode, Lsm303agr, MagOutputDataRate};

pub fn init() -> (Leds, Lsm303agr<I2cInterface<I2c<I2C1, (PB6<AF4>, PB7<AF4>)>>, mode::MagContinuous>, Delay, ITM) {
    let cp = cortex_m::Peripherals::take().unwrap();
    let dp = stm32f30x::Peripherals::take().unwrap();

    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();

    let clocks = rcc.cfgr.freeze(&mut flash.acr);

    let gpioe = dp.GPIOE.split(&mut rcc.ahb);
    let leds = Leds::new(gpioe);

    let mut gpiob = dp.GPIOB.split(&mut rcc.ahb);
    let scl = gpiob.pb6.into_af4(&mut gpiob.moder, &mut gpiob.afrl);
    let sda = gpiob.pb7.into_af4(&mut gpiob.moder, &mut gpiob.afrl);

    let i2c = I2c::i2c1(dp.I2C1, (scl, sda), 400.khz(), clocks, &mut rcc.apb1);

    let mut lsm = Lsm303agr::new_with_i2c(i2c);
    lsm.init().unwrap();
    lsm.set_mag_odr(MagOutputDataRate::Hz10).unwrap();
    let lsm303agr = lsm.into_mag_continuous().ok().unwrap();

    let delay = Delay::new(cp.SYST, clocks);

    (leds, lsm303agr, delay, cp.ITM)
}

3. Use the lsm303agr in the 15-led-compass/src/main.rs like this:

#![deny(unsafe_code)]
#![no_main]
#![no_std]

#[allow(unused_imports)]
use aux15::{entry, iprint, iprintln, prelude::*, UnscaledMeasurement};
use aux15::Direction;

#[entry]
fn main() -> ! {
    let (mut leds, mut lsm303agr, mut delay, mut itm) = aux15::init();

    loop {
        let status = lsm303agr.mag_status().unwrap();
        if status.xyz_new_data {
            let data = lsm303agr.mag_data().unwrap();
            iprintln!(&mut itm.stim[0], "{:?}", data);
        }

        delay.delay_ms(1_000_u16);
    }
}

Hope this helps.

[NitinSaxenait]

Hi, @eisnstein I am also working on the same Chapter of Discovery Book. I was too stuck because of this lsm303dlhc & lsm303agr but your solution really helped me. I have successfully completed the Take 1.
I have one doubt in the src/main.rs
if status.xyz_new_data { let data = lsm303agr.mag_data().unwrap(); iprintln!(&mut itm.stim[0], "{:?}", data); }
I know we are reading the data from the Magnetometer's register using let status = lsm303agr.mag_status().unwrap(); but what we are doing with the if block here? what is this status.xyz_newdata is doing here?? Thanks.