How to use i2c_external with microbit-v2? #121
Description
Hi,
I'm attempting to read from shtc3 sensor connected to microbit-v2 via i2c external pins. For testing, I'm using a minimal RTIC app with one task which received a local context containing the Twim:<TWIM0> instance which it uses to instantiate shtc3. When attempting to build the application, it results in unsatisfied trait bounds:
error[E0599]: the method `device_identifier` exists for struct `ShtCx<Sht2Gen, &mut Twim<TWIM0>>`, but its trait bounds were not satisfied
--> app\src\main.rs:157:29
|
157 | let device_id = sht.device_identifier().unwrap();
| ^^^^^^^^^^^^^^^^^ method cannot be called on `ShtCx<Sht2Gen, &mut Twim<TWIM0>>` due to unsatisfied trait bounds
|
= note: the following trait bounds were not satisfied:
`<&mut microbit::nrf52833_hal::Twim<microbit::nrf52833_pac::TWIM0> as _embedded_hal_blocking_i2c_Read>::Error = _`
`<&mut microbit::nrf52833_hal::Twim<microbit::nrf52833_pac::TWIM0> as _embedded_hal_blocking_i2c_Write>::Error = _`
`&mut microbit::nrf52833_hal::Twim<microbit::nrf52833_pac::TWIM0>: _embedded_hal_blocking_i2c_Read`
`&mut microbit::nrf52833_hal::Twim<microbit::nrf52833_pac::TWIM0>: _embedded_hal_blocking_i2c_Write`
If I move the code to init(), then it compiles fine, but there is no activity on the i2c external pins (checked with an oscilloscope) and every transaction results in a Nack.
Is there anything else I need to do to get i2c_external to work? Here's a minimal version of my code:
#[app(device = microbit::hal::pac)]
mod app {
use super::*;
#[shared]
struct Shared {}
#[local]
struct Local {
led: P0_21<Output<PushPull>>,
// i2c: Twim<TWIM0>,
gpiote: Gpiote,
state: bool,
}
#[init]
fn init(cx: init::Context) -> (Shared, Local) {
info!("Hello from RTIC on micro:bit v2");
let mut board = Board::new(cx.device, cx.core);
let i2c = Twim::new(board.TWIM0, board.i2c_external.into(), FREQUENCY_A::K100);
let mut sht = shtcx::shtc3(i2c);
let device_id = sht.device_identifier().unwrap(); // Fails here with Nack
(
Shared {},
Local {},
)
}