Initialize i2c and return handle

Embedded
1

I've got some i2c code working and reading/writing the SX1509. But now I'd like to refactor the code into functions and I'm having some trouble.

Working code:

    let per = Peripherals::take().unwrap();
    // init::i2c_peripheral(&per);
    let sda = per.pins.gpio4.into_input_output().unwrap();
    let scl = per.pins.gpio5.into_output().unwrap();
    let i2c = per.i2c0;

    let config = <i2c::config::MasterConfig as Default>::default().baudrate(400.kHz().into());
    let mut i2c =
        i2c::Master::<i2c::I2C0, _, _>::new(i2c, i2c::MasterPins { sda, scl }, config).unwrap();

    let mut expander = sx1509::Sx1509::new(&mut i2c, sx1509::DEFAULT_ADDRESS);
    expander.borrow(&mut i2c).software_reset().unwrap();
    expander.borrow(&mut i2c).set_bank_a_direction(0).unwrap();
    expander
        .borrow(&mut i2c)
        .set_bank_b_direction(0xFF)
        .unwrap();

Non-working i2c init function:

use crate::helpers;
use esp_idf_hal::i2c;
use esp_idf_hal::prelude::*;
use esp_idf_hal::units::FromValueType;

pub fn i2c_peripheral(
    per: &Peripherals,
) -> i2c::Master<
    i2c::I2C0,
    esp_idf_hal::peripherals::Peripherals::pins::gpio4,
    esp_idf_hal::peripherals::Peripherals::pins::gpio5,
> {
    let sda = per.pins.gpio4.into_input_output().unwrap();
    let scl = per.pins.gpio5.into_output().unwrap();
    let i2c = per.i2c0;

    let config = <i2c::config::MasterConfig as Default>::default().baudrate(400.kHz().into());
    let i2c =
        i2c::Master::<i2c::I2C0, _, _>::new(i2c, i2c::MasterPins { sda, scl }, config).unwrap();

    helpers::ptype(&i2c);
    i2c
}

Thanks for any advice or comments.

2

In what way does it not work, exactly?

3

i2c_peripheral() results in the error:

error[E0223]: ambiguous associated type
  --> src/init.rs:10:5
   |
10 |     esp_idf_hal::peripherals::Peripherals::pins::gpio4,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<esp_idf_hal::peripherals::Peripherals as Trait>::pins`

error[E0223]: ambiguous associated type
  --> src/init.rs:11:5
   |
11 |     esp_idf_hal::peripherals::Peripherals::pins::gpio5,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<esp_idf_hal::peripherals::Peripherals as Trait>::pins`
4

esp_idf_hal::peripherals::Peripherals appears to be a struct. You can't refer to the type of fields in a struct with a path like that, you just need to use the actual type.

In this case I believe it should be

pub fn i2c_peripheral(
    per: &Peripherals,
) -> i2c::Master<
    i2c::I2C0,
    esp_idf_hal::gpio::Gpio4<esp_idf_hal::gpio::Unknown>,
    esp_idf_hal::gpio::Gpio5<esp_idf_hal::gpio::Unknown>,
> {
2 Likes
5

Thank you @semicoleon! That worked, except I had to add the InputOutput and Output type to the gpio's or I get the error:

i2c
   |       ^^^ expected struct `esp_idf_hal::gpio::Unknown`, found struct `InputOutput`

The code that works ended up being:

pub fn i2c_peripheral(
    per: Peripherals,
) -> i2c::Master<
    i2c::I2C0,
    esp_idf_hal::gpio::Gpio4<esp_idf_hal::gpio::InputOutput>,
    esp_idf_hal::gpio::Gpio5<esp_idf_hal::gpio::Output>,
> {
    // init::i2c_peripheral(&per);
    let sda = per.pins.gpio4.into_input_output().unwrap();
    let scl = per.pins.gpio5.into_output().unwrap();
    let i2c = per.i2c0;

    let config = <i2c::config::MasterConfig as Default>::default().baudrate(400.kHz().into());
    let i2c =
        i2c::Master::<i2c::I2C0, _, _>::new(i2c, i2c::MasterPins { sda, scl }, config).unwrap();
    i2c
}
6

Oh yeah if your function is initializing the pins that makes sense that you needed to change that type!

7

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