Module capsules_core::button

Provides userspace control of buttons on a board.

This allows for much more cross platform controlling of buttons without having to know which of the GPIO pins exposed across the syscall interface are buttons.

Usage

let button_pins = static_init!(
    [&'static sam4l::gpio::GPIOPin; 1],
    [&sam4l::gpio::PA[16]]);
let button = static_init!(
    capsules::button::Button<'static>,
    capsules::button::Button::new(button_pins, board_kernel.create_grant(&grant_cap)));
for btn in button_pins.iter() {
    btn.set_client(button);
}

Syscall Interface

• Stability: 2 - Stable

Command

Enable or disable button interrupts and read the current button state.

command_num

• 0: Driver existence check and get number of buttons on the board.
• 1: Enable interrupts for a given button. This will enable both press and depress events.
• 2: Disable interrupts for a button. No affect or reliance on registered callback.
• 3: Read the current state of the button.

Subscribe

Setup a callback for button presses.

subscribe_num

• 0: Set callback for pin interrupts. Note setting this callback has no reliance on individual pins being configured as interrupts. The interrupt will be called with two parameters: the index of the button that triggered the interrupt and the pressed (1) or not pressed (0) state of the button.

Structs

• App
  This capsule keeps track for each app of which buttons it has a registered interrupt for. SubscribeMap is a bit array where bits are set to one if that app has an interrupt registered for that button.
• Button
  Manages the list of GPIO pins that are connected to buttons and which apps are listening for interrupts from which buttons.

Constants

• DRIVER_NUM

Type Aliases

• SubscribeMap
  This capsule keeps track for each app of which buttons it has a registered interrupt for. SubscribeMap is a bit array where bits are set to one if that app has an interrupt registered for that button.