Buttons & External Interrupts

This section covers functions related to the three buttons: Light, Mode and Alarm, as well as external interrupts from devices on the nine-pin connector. More...

Typedefs
typedef enum watch_interrupt_trigger	watch_interrupt_trigger
	An enum defining the types of interrupt trigger you wish to scan for.

Enumerations
enum	watch_interrupt_trigger { INTERRUPT_TRIGGER_NONE = 0 , INTERRUPT_TRIGGER_RISING , INTERRUPT_TRIGGER_FALLING , INTERRUPT_TRIGGER_BOTH }
	An enum defining the types of interrupt trigger you wish to scan for.

Functions
void	watch_enable_external_interrupts (void)
	Enables the external interrupt controller.
void	watch_disable_external_interrupts (void)
	Disables the external interrupt controller.
void	watch_register_interrupt_callback (const uint8_t pin, ext_irq_cb_t callback, watch_interrupt_trigger trigger)
	Configures an external interrupt callback on one of the external interrupt pins.

Detailed Description

This section covers functions related to the three buttons: Light, Mode and Alarm, as well as external interrupts from devices on the nine-pin connector.

The buttons are the core input UI of the watch, and the way the user will interact with your application. They are active high, pulled down by the microcontroller, and triggered when one of the "pushers" brings a tab from the metal frame into contact with the edge of the board. Note that the buttons can only wake the watch from STANDBY mode, at least as of the current SAM L22 silicon revision. The external interrupt controller runs in STANDBY mode, but it does not run in BACKUP mode; to wake from BACKUP, buttons will not cut it.

Function Documentation

watch_register_interrupt_callback()

void watch_register_interrupt_callback	(	const uint8_t	pin,
		ext_irq_cb_t	callback,
		watch_interrupt_trigger	trigger
	)

Configures an external interrupt callback on one of the external interrupt pins.

You can set one interrupt callback per pin, and you can monitor for a rising condition, a falling condition, or both. If you just want to detect a button press, register your interrupt with INTERRUPT_TRIGGER_RISING; if you want to detect an active-low interrupt signal from a device on the nine-pin connector, use INTERRUPT_TRIGGER_FALLING. If you want to detect both rising and falling conditions (i.e. button down and button up), use INTERRUPT_TRIGGER_BOTH and use watch_get_pin_level to check the pin level in your callback to determine which condition caused the interrupt.

Parameters

pin	One of BTN_LIGHT, BTN_MODE, BTN_ALARM, A0, A1, A3 or A4. If the pin parameter matches one of the three button pins, this function will also enable an internal pull-down resistor. If the pin parameter is A0-A4, you are responsible for setting any required pull configuration using watch_enable_pull_up or watch_enable_pull_down.
callback	The function you wish to have called when the button is pressed.
trigger	The condition on which you wish to trigger: rising, falling or both.

Note

Pins A2 and A4 can also generate interrupts via the watch_register_extwake_callback function, which will allow them to trigger even when the watch is in deep sleep mode.

Warning

As of now, A2 is not usable via the watch_register_interrupt_callback function. To enable an external interrupt on pin A2, use the watch_register_extwake_callback function. This issue will be addressed in a future revision of the watch library.