atsamd_hal::gpio

Module pin

Source
Expand description

§Type-level module for GPIO pins

This module provides a type-level API for GPIO pins. It uses the type system to track the state of pins at compile-time. Representing GPIO pins in this manner incurs no run-time overhead. Each Pin struct is zero-sized, so there is no data to copy around. Instead, real code is generated as a side effect of type transformations, and the resulting assembly is nearly identical to the equivalent, hand-written C.

To track the state of pins at compile-time, this module uses traits to represent type classes and types as instances of those type classes. For example, the trait InputConfig acts as a type-level enum of the available input configurations, and the types Floating, PullDown and PullUp are its type-level variants.

Type-level Pins are parameterized by two type-level enums, PinId and PinMode.

pub struct Pin<I, M>
where
    I: PinId,
    M: PinMode,
{
    // ...
}

A PinId identifies a pin by it’s group (A, B, C or D) and pin number. Each PinId instance is named according to its datasheet identifier, e.g. PA02.

A PinMode represents the various pin modes. The available PinMode variants are Disabled, Input, Interrupt, Output and Alternate, each with its own corresponding configurations.

It is not possible for users to create new instances of a Pin. Singleton instances of each pin are made available to users through the Pins struct.

To create the Pins struct, users must supply the PAC Port peripheral. The Pins struct takes ownership of the Port and provides the corresponding pins. Each Pin within the Pins struct can be moved out and used individually.

let mut peripherals = Peripherals::take().unwrap();
let pins = Pins::new(peripherals.Port);

Pins can be converted between modes using several different methods.

// Use one of the literal function names
let pa27 = pins.pa27.into_floating_input();
// Use a generic method and one of the `PinMode` variant types
let pa27 = pins.pa27.into_mode::<FloatingInput>();
// Specify the target type and use `From`/`Into`
let pa27: Pin<PA27, FloatingInput> = pins.pa27.into();

§Embedded HAL traits

This module implements all of the embedded HAL GPIO traits for each Pin in the corresponding PinModes, namely: InputPin, OutputPin, [ToggleableOutputPin] and StatefulOutputPin.

For example, you can control the logic level of an OutputPin like so

use atsamd_hal::pac::Peripherals;
use atsamd_hal::gpio::Pins;
use crate::ehal_02::digital::v2::OutputPin;

let mut peripherals = Peripherals::take().unwrap();
let mut pins = Pins::new(peripherals.Port);
pins.pa27.set_high();

§Type-level features

This module also provides additional, type-level tools to work with GPIO pins.

The OptionalPinId and OptionalPin traits use the OptionalKind pattern to act as type-level versions of Option for PinId and Pin respectively. And the AnyPin trait defines an AnyKind type class for all Pin types.

Structs§

Enums§

  • B
    Type-level variant of AlternateConfig for alternate peripheral function B
  • C
    Type-level variant of AlternateConfig for alternate peripheral function C
  • D
    Type-level variant of AlternateConfig for alternate peripheral function D
  • E
    Type-level variant of AlternateConfig for alternate peripheral function E
  • F
    Type-level variant of AlternateConfig for alternate peripheral function F
  • Floating
    Type-level variant of both DisabledConfig and InputConfig
  • G
    Type-level variant of AlternateConfig for alternate peripheral function G
  • H
    Type-level variant of AlternateConfig for alternate peripheral function H
  • PA00
    Pin ID representing pin PA00
  • PA01
    Pin ID representing pin PA01
  • PA02
    Pin ID representing pin PA02
  • PA03
    Pin ID representing pin PA03
  • PA04
    Pin ID representing pin PA04
  • PA05
    Pin ID representing pin PA05
  • PA06
    Pin ID representing pin PA06
  • PA07
    Pin ID representing pin PA07
  • PA08
    Pin ID representing pin PA08
  • PA09
    Pin ID representing pin PA09
  • PA10
    Pin ID representing pin PA10
  • PA11
    Pin ID representing pin PA11
  • PA12
    Pin ID representing pin PA12
  • PA13
    Pin ID representing pin PA13
  • PA14
    Pin ID representing pin PA14
  • PA15
    Pin ID representing pin PA15
  • PA16
    Pin ID representing pin PA16
  • PA17
    Pin ID representing pin PA17
  • PA18
    Pin ID representing pin PA18
  • PA19
    Pin ID representing pin PA19
  • PA20
    Pin ID representing pin PA20
  • PA21
    Pin ID representing pin PA21
  • PA22
    Pin ID representing pin PA22
  • PA23
    Pin ID representing pin PA23
  • PA24
    Pin ID representing pin PA24
  • PA25
    Pin ID representing pin PA25
  • PA27
    Pin ID representing pin PA27
  • PA28
    Pin ID representing pin PA28
  • PA30
    Pin ID representing pin PA30
  • PA31
    Pin ID representing pin PA31
  • PB02
    Pin ID representing pin PB02
  • PB03
    Pin ID representing pin PB03
  • PB08
    Pin ID representing pin PB08
  • PB09
    Pin ID representing pin PB09
  • PB10
    Pin ID representing pin PB10
  • PB11
    Pin ID representing pin PB11
  • PB22
    Pin ID representing pin PB22
  • PB23
    Pin ID representing pin PB23
  • PullDown
    Type-level variant of both DisabledConfig and InputConfig
  • PullUp
    Type-level variant of both DisabledConfig and InputConfig
  • PushPull
    Type-level variant of OutputConfig for a push-pull configuration
  • Readable
    Type-level variant of OutputConfig for a readable push-pull configuration

Traits§

Type Aliases§