timers.h File Reference

Contains defines, macros and functions for ARM7 and ARM9 timer operation. More...

#include <nds/ndstypes.h>

Macros
#define	BUS_CLOCK   (33513982)
	The speed in which the timer ticks in Hz.
#define	TIMER0_CR   (*(vu16 *)0x04000102)
	Same as TIMER_CR(0).
#define	TIMER0_DATA   (*(vu16 *)0x04000100)
	Same as TIMER_DATA(0).
#define	TIMER1_CR   (*(vu16 *)0x04000106)
	Same as TIMER_CR(1).
#define	TIMER1_DATA   (*(vu16 *)0x04000104)
	Same as TIMER_DATA(1).
#define	TIMER2_CR   (*(vu16 *)0x0400010A)
	Same as TIMER_CR(2).
#define	TIMER2_DATA   (*(vu16 *)0x04000108)
	Same as TIMER_DATA(2).
#define	TIMER3_CR   (*(vu16 *)0x0400010E)
	Same as TIMER_CR(3).
#define	TIMER3_DATA   (*(vu16 *)0x0400010C)
	Same as TIMER_DATA(3).
#define	TIMER_CASCADE   (1 << 2)
	When set will cause the timer to count when the timer below overflows (unavailable for timer 0).
#define	TIMER_CR(n)   (*(vu16 *)(0x04000102 + ((n) << 2)))
	Returns a dereferenced pointer to the data register for timer control register.
#define	TIMER_DATA(n)   (*(vu16 *)(0x04000100 + ((n) << 2)))
	Returns a dereferenced pointer to the data register for timer number "n".
#define	TIMER_DIV_1   (0)
	Causes the timer to count at 33.514 MHz.
#define	TIMER_DIV_1024   (3)
	Causes the timer to count at (33.514 / 1024) MHz.
#define	TIMER_DIV_256   (2)
	Causes the timer to count at (33.514 / 256) MHz.
#define	TIMER_DIV_64   (1)
	Causes the timer to count at (33.514 / 64) MHz.
#define	TIMER_ENABLE   (1 << 7)
	Enables the timer.
#define	TIMER_FREQ(n)   TIMER_FREQ_SHIFT(n, 1, 0)
	A macro that calculates TIMER_DATA(n) settings for a given frequency of n.
#define	TIMER_FREQ_1024(n)   TIMER_FREQ_SHIFT(n, 1, 10)
	Macro that calculates TIMER_DATA(n) settings for a given frequency of n.
#define	TIMER_FREQ_256(n)   TIMER_FREQ_SHIFT(n, 1, 8)
	A macro that calculates TIMER_DATA(n) settings for a given frequency of n.
#define	TIMER_FREQ_64(n)   TIMER_FREQ_SHIFT(n, 1, 6)
	A macro that calculates TIMER_DATA(n) settings for a given frequency of n.
#define	TIMER_FREQ_SHIFT(n, divisor, shift)   ((-((BUS_CLOCK >> (shift)) * (divisor)) - ((((n) + 1)) >> 1)) / (n))
	A macro that calculates TIMER_DATA(n) settings for a given frequency of n and shift. Correctly rounds the timer to the closest available frequency.
#define	TIMER_IRQ_REQ   (1 << 6)
	Causes the timer to request an Interrupt on overflow.

Enumerations
enum	ClockDivider {   ClockDivider_1 = 0 ,   ClockDivider_64 = 1 ,   ClockDivider_256 = 2 ,   ClockDivider_1024 = 3 }
	Allowable timer clock dividers. More...

Functions
u32	cpuEndTiming (void)
	Ends CPU timing.
u32	cpuGetTiming (void)
	Returns the number of ticks which have elapsed since cpuStartTiming.
void	cpuStartTiming (int timer)
	Begins CPU timing using two timers for 32bit resolution.
u16	timerElapsed (int timer)
	Returns the ticks elapsed since the last call to timerElapsed().
u16	timerPause (int timer)
	Pauses the specified timer.
void	timerStart (int timer, ClockDivider divider, u16 ticks, VoidFn callback)
	Start a hardware timer.
u16	timerStop (int timer)
	Stops the specified timer.
static u16	timerTick (int timer)
	Returns the raw ticks of the specified timer.
static void	timerUnpause (int timer)
	Unpauses the specified timer.

Detailed Description

Contains defines, macros and functions for ARM7 and ARM9 timer operation.

It also contains a simplified API for timer use and some cpu timing functions.

The timers are fed with a 33.513982 MHz source on the ARM9 and ARM7.

Note

that DSWifi will use timer 3 on the ARM9, so don't use that if you use DSWifi.

Macro Definition Documentation

TIMER_CR

#define TIMER_CR

(

n

)

(*(vu16 *)(0x04000102 + ((n) << 2)))

Returns a dereferenced pointer to the data register for timer control register.

Example Usage:

TIMER_CR(x) = TIMER_ENABLE | ClockDivider_64;

Possible bit defines:

See also

TIMER_ENABLE

TIMER_IRQ_REQ

TIMER_CASCADE

ClockDivider

TIMER_DATA

#define TIMER_DATA

(

n

)

(*(vu16 *)(0x04000100 + ((n) << 2)))

Returns a dereferenced pointer to the data register for timer number "n".

See also

TIMER_CR(n)

TIMER_FREQ(n)

TIMER_DATA(n) when set will latch that value into the counter. Every time the counter rolls over, TIMER_DATA(0) will return to the latched value. This allows you to control the frequency of the timer using the following formula:

TIMER_DATA(x) = -(BUS_CLOCK / (freq * divider));

Example Usage:

TIMER_DATA(0) = value; // 0 to 3. value is 16 bits

TIMER_FREQ

#define TIMER_FREQ

(

n

)

TIMER_FREQ_SHIFT(n, 1, 0)

A macro that calculates TIMER_DATA(n) settings for a given frequency of n.

It will calculate the correct value for TIMER_DATA(n) given the frequency in Hz (number of times the timer should overflow per second).

Example Usage:

// Calls the timerCallBack function 5000 times per second.
timerStart(0, ClockDivider_1, TIMER_FREQ(5000), timerCallBack);

Max frequency is: 33513982 Hz Min frequency is: ~511 Hz

Note

Use the appropriate macro depending on the used clock divider.

TIMER_FREQ_1024

#define TIMER_FREQ_1024

(

n

)

TIMER_FREQ_SHIFT(n, 1, 10)

Macro that calculates TIMER_DATA(n) settings for a given frequency of n.

It wtill calculate the correct value for TIMER_DATA(n) given the frequency in Hz (number of times the timer should overflow per second).

Example Usage:

// Calls the timerCallBack function 5 times per second.
timerStart(0, ClockDivider_1024, TIMER_FREQ_1024(5), timerCallBack);

Max frequency is: ~32728 Hz Min frequency is: ~0.5 Hz

Note

Use the appropriate macro depending on the used clock divider.

TIMER_FREQ_256

#define TIMER_FREQ_256

(

n

)

TIMER_FREQ_SHIFT(n, 1, 8)

A macro that calculates TIMER_DATA(n) settings for a given frequency of n.

It will calculate the correct value for TIMER_DATA(n) given the frequency in Hz (number of times the timer should overflow per second).

Example Usage:

// Calls the timerCallBack function 50 times per second.
timerStart(0, ClockDivider_256, TIMER_FREQ_256(50), timerCallBack);

Max frequency is: ~130914 Hz Min frequency is: ~2 Hz

Note

Use the appropriate macro depending on the used clock divider.

TIMER_FREQ_64

#define TIMER_FREQ_64

(

n

)

TIMER_FREQ_SHIFT(n, 1, 6)

A macro that calculates TIMER_DATA(n) settings for a given frequency of n.

It will calculate the correct value for TIMER_DATA(n) given the frequency in Hz (number of times the timer should overflow per second).

Example Usage:

// Calls the timerCallBack function 500 times per second.
timerStart(0, ClockDivider_64, TIMER_FREQ_64(500), timerCallBack);

Max frequency is: ~523656 Hz Min frequency is: 8 Hz

Note

Use the appropriate macro depending on the used clock divider.

TIMER_FREQ_SHIFT

#define TIMER_FREQ_SHIFT	(		n,
			divisor,
			shift
	)		((-((BUS_CLOCK >> (shift)) * (divisor)) - ((((n) + 1)) >> 1)) / (n))

A macro that calculates TIMER_DATA(n) settings for a given frequency of n and shift. Correctly rounds the timer to the closest available frequency.

Shift values:

• ClockDivider_1 = 0
• ClockDivider_64 = 6
• ClockDivider_256 = 8
• ClockDivider_1024 = 10
• ARM7 sound timer = 1

Enumeration Type Documentation

ClockDivider

enum ClockDivider

Allowable timer clock dividers.

Enumerator
ClockDivider_1	Divides the timer clock by 1 (~33513.982 kHz)
ClockDivider_64	Divides the timer clock by 64 (~523.657 kHz)
ClockDivider_256	Divides the timer clock by 256 (~130.914 kHz)
ClockDivider_1024	divides the timer clock by 1024 (~32.7284 kHz)

Function Documentation

cpuEndTiming()

u32 cpuEndTiming

(

void

)

Ends CPU timing.

Returns

The number of ticks which have elapsed since cpuStartTiming.

cpuGetTiming()

u32 cpuGetTiming

(

void

)

Returns the number of ticks which have elapsed since cpuStartTiming.

Returns

The number of ticks which have elapsed since cpuStartTiming.

cpuStartTiming()

void cpuStartTiming

(

int

timer

)

Begins CPU timing using two timers for 32bit resolution.

Parameters

timer

The base hardware timer to use (0 - 2).

timerElapsed()

u16 timerElapsed

(

int

timer

)

Returns the ticks elapsed since the last call to timerElapsed().

Parameters

timer

The hardware timer to use (0 - 3).

Returns

The number of ticks which have elapsed since the last call to timerElapsed().

timerPause()

u16 timerPause

(

int

timer

)

Pauses the specified timer.

Parameters

timer

The hardware timer to use (0 - 3).

Returns

The number of ticks which have elapsed since the last call to timerElapsed().

timerStart()

void timerStart	(	int	timer,
		ClockDivider	divider,
		u16	ticks,
		VoidFn	callback
	)

Start a hardware timer.

Callback is tied directly to interrupt table and called directly, resulting in less latency than the attached timer.

Parameters

timer	The hardware timer to use (0 - 3).
divider	The timer channel clock divider (clock will tick at 33.513982 MHz / divider).
ticks	The number of ticks which must elapse before the timer overflows.
callback	The callback to be called when the timer expires (if NULL, no IRQ will be generated by the timer).

timerStop()

u16 timerStop

(

int

timer

)

Stops the specified timer.

Parameters

timer

The hardware timer to use (0 - 3).

Returns

The number of ticks which have elapsed since the last call to timerElapsed().

timerTick()

static u16 timerTick ( int  timer )

inlinestatic

Returns the raw ticks of the specified timer.

Parameters

timer

The hardware timer to use (0 - 3).

Returns

The raw ticks of the specified timer data register.

timerUnpause()

static void timerUnpause ( int  timer )

inlinestatic

Unpauses the specified timer.

Parameters

timer

The hardware timer to use (0 - 3).