timer.h File Reference

openchronos-ng timer driver More...

#include <openchronos.h>

Go to the source code of this file.

Enumerations
enum	timer0_event { TIMER0_EVENT_1HZ = BIT0, TIMER0_EVENT_20HZ = BIT1, TIMER0_EVENT_PROG = BIT2 }
	Bitfield of events produced by this driver. More...
Functions
void	timer0_init (void)
	Initializes the timer.
void	timer0_create_prog_timer (uint16_t duration)
	creates a 1000Hz - 1Hz programmable timer
void	timer0_destroy_prog_timer ()
	destroys a running programmable timer
void	timer0_delay (uint16_t duration, uint16_t LPM_bits)
	1ms - 1s programmable delay
Variables
volatile uint16_t	timer0_20hz_counter
	20Hz counter.
enum timer0_event	timer0_last_event
	Bitfield holding the last generated (timer) event.

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Detailed Description

openchronos-ng timer driver

This driver takes care of the Timer0 hardware timer. From this hardware timer the driver produces two hardware-based timers running at 20Hz and 1Hz. The events produced by those timers are available in sys_message. Beyound the fixed frequency timers, this driver also implements a programmable timer and a programmable delay.

Note:

If you are looking to timer events, then see sys_message

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Enumeration Type Documentation

enum timer0_event

Bitfield of events produced by this driver.

Enumerator:

TIMER0_EVENT_1HZ	1Hz event
TIMER0_EVENT_20HZ	20Hz event
TIMER0_EVENT_PROG	programmable timer event

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Function Documentation

void timer0_create_prog_timer

(

uint16_t

duration

)

creates a 1000Hz - 1Hz programmable timer

Creates a timer programmable from 1Hz up to 1000Hz. The timer event is available in sys_message.

Note:

You should check what modules are using this function because it cannot be used by more than one module at same time. We recommend you use one of the available fixed timers. If you really need another ticking frequency, contact the openchronos-ng developers for a better solution.

See also:

timer0_destroy_prog_timer

Parameters:

duration

timer period between 1 and 1000 milliseconds.

void timer0_delay	(	uint16_t	duration,
		uint16_t	LPM_bits
	)

1ms - 1s programmable delay

delays execution for duration milliseconds. During the delay, interrupts are still generated but sys_message only broadcasts the events after the delay has finished. The second argument is put directly into the _STATUS_ register. This could of course disrupt the state of the watch. Please be careful and take a look at http://mspgcc.sourceforge.net/manual/x1028.html for information regarding the _STATUS_ register.

Note:

Please avoid using this. No processing is done in the background during the delay, which can have impact in modules that require a responsive system.

Parameters:

duration	delay duration between 1 and 1000 milliseconds
LPM_bits	LPM bits to put in the status register, so the user can choose LPM level

void timer0_destroy_prog_timer

(

)

destroys a running programmable timer

See also:

timer0_create_prog_timer

void timer0_init

(

void

)

Initializes the timer.

This functions is called once upon system initialization.

Note:

Modules are strictly forbidden to call this function.

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Variable Documentation

volatile uint16_t timer0_20hz_counter

20Hz counter.

This is a counter variable, its value is updated at 20Hz. You can use this to measure timings.

Note:

counter overflows should be relatively safe since they only happen once each 3276.8 seconds. However you should handle overflows if your application cannot accept sporadic failures in measurement.

enum timer0_event timer0_last_event

Bitfield holding the last generated (timer) event.

Timer0 interrupt routines update this variable with the last happening events. Inside the mainloop, the system then clears this variable after reading it. Read events are broadcasted in sys_message.

Note:

This function is to be used exclusively by the system. No module is allowed to read or write to this variable.