button.h File Reference

The button module enables event-driven and polling access to the buttons of the SPiCboard. More...

#include <stdint.h>

Go to the source code of this file.

Typedefs
typedef void(*	buttoncallback_t )(BUTTON, BUTTONEVENT)
	Type for button event callback functions.
Enumerations
enum	BUTTON { BUTTON0 = 4, BUTTON1 = 8 }
	Identifiers for all available buttons. More...
enum	BUTTONEVENT { BTNPRESSED = 1, BTNRELEASED = 2 }
	Events for buttons. More...
Functions
int8_t	sb_button_registerListener (BUTTON btn, BUTTONEVENT eve, buttoncallback_t callback)
	Register a callback function for a button event.
int8_t	sb_button_unregisterListener (BUTTON btn, BUTTONEVENT eve, buttoncallback_t callback)
	Unregister a callback function for a button event.
BUTTONEVENT	sb_button_getState (BUTTON btn)
	Query the current state of a button.

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Detailed Description

The button module enables event-driven and polling access to the buttons of the SPiCboard.

Version:

$Rev: 149 $

The SPiCboard is equipped with two buttons. Button 0 is debounced in hardware, whereas Button 1 needs to be debounced in software by the button module. Debouncing is transparent to the application, that can use both buttons through the provided interface without the need to care about debouncing.

The debouncing code makes use of the timer module. When no listeners are registered for Button 1, the debouncing code is disabled and all alarms registered at the timer should be canceled.

The button module uses dynamic memory management to maintain the listener queues.

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Typedef Documentation

typedef void(* buttoncallback_t)(BUTTON, BUTTONEVENT)

Type for button event callback functions.

A button callback function is called on the interrupt level whenever an event at a button occurs that the function was registered for. The callback function is passed the button id and the type of event that occurred. This way, the same callback function can be registered for different buttons and events.

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Enumeration Type Documentation

enum BUTTON

Identifiers for all available buttons.

Enumerator:

BUTTON0	Button 0
BUTTON1	Button 1

enum BUTTONEVENT

Events for buttons.

Pressed and released events for buttons.

Enumerator:

BTNPRESSED	Button was pressed
BTNRELEASED	Button was released

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Function Documentation

BUTTONEVENT sb_button_getState

(

BUTTON

btn

)

Query the current state of a button.

Parameters:

btn

id of the button

Returns:

The buttons current state (pressed or released) as a button event

int8_t sb_button_registerListener	(	BUTTON	btn,
		BUTTONEVENT	eve,
		buttoncallback_t	callback
	)

Register a callback function for a button event.

Parameters:

	btn	the id of the button
	eve	the type of event that the callback function should be invoked for. event types can be bitwise or'd to register a callback for both pressed and released events.
	callback	pointer to the callback function

Returns:

0 on success, negative value on error

int8_t sb_button_unregisterListener	(	BUTTON	btn,
		BUTTONEVENT	eve,
		buttoncallback_t	callback
	)

Unregister a callback function for a button event.

Parameters:

	btn	the id of the button
	eve	the type of event that the callback function should be invoked for. event types can be bitwise or'd to register a callback for both pressed and released events.
	callback	pointer to the callback function

Returns:

0 on success, negative value on error

Return values:

	0	success
	-1	the callback function was not registered with the given button/event combination