Module gpio

General Purpose I/Os

The GPIO pins are organised into groups of 16 pins which can be accessed through the gpioa, gpiob… modules. To get access to the pins, you first need to convert them into a HAL designed struct from the pac struct using the split function.

// Acquire the GPIOC peripheral
// NOTE: `dp` is the device peripherals from the `PAC` crate
let mut gpioa = dp.GPIOA.split();

This gives you a struct containing two control registers crl and crh, and all the pins px0..px15. These structs are what you use to interract with the pins to change their modes, or their inputs or outputs. For example, to set pa5 high, you would call

let output = gpioa.pa5.into_push_pull_output(&mut gpioa.crl);
output.set_high();

Modes

Each GPIO pin can be set to various modes:

• Alternate: Pin mode required when the pin is driven by other peripherals
• Dynamic: Pin mode is selected at runtime. See changing configurations for more details
• Input
  • PullUp: Input connected to high with a weak pull up resistor. Will be high when nothing is connected
  • PullDown: Input connected to high with a weak pull up resistor. Will be low when nothing is connected
  • Floating: Input not pulled to high or low. Will be undefined when nothing is connected
• Output
  • PushPull: Output which either drives the pin high or low
  • OpenDrain: Output which leaves the gate floating, or pulls it do ground in drain mode. Can be used as an input in the open configuration
• Debugger: Some pins start out being used by the debugger. A pin in this mode can only be used if the JTAG peripheral has been turned off.

Changing modes

The simplest way to change the pin mode is to use the into_<mode> functions. These return a new struct with the correct mode that you can use the input or output functions on.

If you need a more temporary mode change, and can not use the into_<mode> functions for ownership reasons, you can use the as_<mode> functions to temporarily change the pin type, do some output or input, and then have it change back once done.

Dynamic Mode Change

The above mode change methods guarantee that you can only call input functions when the pin is in input mode, and output when in output modes, but can lead to some issues. Therefore, there is also a mode where the state is kept track of at runtime, allowing you to change the mode often, and without problems with ownership, or references, at the cost of some performance and the risk of runtime errors.

To make a pin dynamic, use the into_dynamic function, and then use the make_<mode> functions to change the mode

Accessing PA15, PB3, and PB14

These pins are used by the JTAG peripheral by default. To use them in your program, you need to disable that peripheral. This is done using the afio::MAPR::disable_jtag function

Interfacing with v1 traits

embedded-hal has two versions of the digital traits, v2 which is used by this crate and v1 which is deprecated but still used by a lot of drivers. If you want to use such a driver with this crate, you need to convert the digital pins to the v1 type.

This is done using embedded-hal::digital::v1_compat::OldOutputPin. For example:

let nss = gpioa.pa4.into_push_pull_output(&mut gpioa.crl);
let mut mfrc522 = Mfrc522::new(spi, OldOutputPin::from(nss)).unwrap();

Re-exports

pub use gpioa::PA0;

pub use gpioa::PA1;

pub use gpioa::PA2;

pub use gpioa::PA3;

pub use gpioa::PA4;

pub use gpioa::PA5;

pub use gpioa::PA6;

pub use gpioa::PA7;

pub use gpioa::PA8;

pub use gpioa::PA9;

pub use gpioa::PA10;

pub use gpioa::PA11;

pub use gpioa::PA12;

pub use gpioa::PA13;

pub use gpioa::PA14;

pub use gpioa::PA15;

pub use gpiob::PB0;

pub use gpiob::PB1;

pub use gpiob::PB2;

pub use gpiob::PB3;

pub use gpiob::PB4;

pub use gpiob::PB5;

pub use gpiob::PB6;

pub use gpiob::PB7;

pub use gpiob::PB8;

pub use gpiob::PB9;

pub use gpiob::PB10;

pub use gpiob::PB11;

pub use gpiob::PB12;

pub use gpiob::PB13;

pub use gpiob::PB14;

pub use gpiob::PB15;

pub use gpioc::PC0;

pub use gpioc::PC1;

pub use gpioc::PC2;

pub use gpioc::PC3;

pub use gpioc::PC4;

pub use gpioc::PC5;

pub use gpioc::PC6;

pub use gpioc::PC7;

pub use gpioc::PC8;

pub use gpioc::PC9;

pub use gpioc::PC10;

pub use gpioc::PC11;

pub use gpioc::PC12;

pub use gpioc::PC13;

pub use gpioc::PC14;

pub use gpioc::PC15;

pub use gpiod::PD0;

pub use gpiod::PD1;

pub use gpiod::PD2;

pub use gpiod::PD3;

pub use gpiod::PD4;

pub use gpiod::PD5;

pub use gpiod::PD6;

pub use gpiod::PD7;

pub use gpiod::PD8;

pub use gpiod::PD9;

pub use gpiod::PD10;

pub use gpiod::PD11;

pub use gpiod::PD12;

pub use gpiod::PD13;

pub use gpiod::PD14;

pub use gpiod::PD15;

pub use gpioe::PE0;

pub use gpioe::PE1;

pub use gpioe::PE2;

pub use gpioe::PE3;

pub use gpioe::PE4;

pub use gpioe::PE5;

pub use gpioe::PE6;

pub use gpioe::PE7;

pub use gpioe::PE8;

pub use gpioe::PE9;

pub use gpioe::PE10;

pub use gpioe::PE11;

pub use gpioe::PE12;

pub use gpioe::PE13;

pub use gpioe::PE14;

pub use gpioe::PE15;

pub use gpiof::PF0;

pub use gpiof::PF1;

pub use gpiof::PF2;

pub use gpiof::PF3;

pub use gpiof::PF4;

pub use gpiof::PF5;

pub use gpiof::PF6;

pub use gpiof::PF7;

pub use gpiof::PF8;

pub use gpiof::PF9;

pub use gpiof::PF10;

pub use gpiof::PF11;

pub use gpiof::PF12;

pub use gpiof::PF13;

pub use gpiof::PF14;

pub use gpiof::PF15;

pub use gpiog::PG0;

pub use gpiog::PG1;

pub use gpiog::PG2;

pub use gpiog::PG3;

pub use gpiog::PG4;

pub use gpiog::PG5;

pub use gpiog::PG6;

pub use gpiog::PG7;

pub use gpiog::PG8;

pub use gpiog::PG9;

pub use gpiog::PG10;

pub use gpiog::PG11;

pub use gpiog::PG12;

pub use gpiog::PG13;

pub use gpiog::PG14;

pub use gpiog::PG15;

Modules

gpioa

GPIO

gpiob

GPIO

gpioc

GPIO

gpiod

GPIO

gpioe

GPIO

gpiof

GPIO

gpiog

GPIO

Structs

Alternate

Alternate function

Analog

Analog mode (type state)

Cr

Opaque CR register

Debugger

Used by the debugger (type state)

Floating

Floating input (type state)

Input

Input mode (type state)

OpenDrain

Open drain output (type state)

Output

Output mode (type state)

PartiallyErasedPin

Partially erased pin

Pin

Generic pin type

PullDown

Pulled down input (type state)

PullUp

Pulled up input (type state)

PushPull

Push pull output (type state)

Enums

Dynamic

Tracks the current pin state for dynamic pins

Edge

ErasedPin

Erased pin

IOPinSpeed

Slew rates available for Output and relevant AlternateMode Pins

PinModeError

PinState

Digital output pin state

Traits

Active

Marker trait for active states.

ExtiPin

External Interrupt Pin

GpioExt

Extension trait to split a GPIO peripheral in independent pins and registers

HL

Represents high or low configuration register

OutputSpeed

Allow setting of the slew rate of an IO pin

PinExt

Type Aliases

EPin

PEPin