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GBA System Timer
[System Support]


Detailed Description

Nut/OS System Timer implemented on the GBA.


Defines

#define NUT_CPU_FREQ   1000000UL
#define NUT_TICK_FREQ   1000UL

Functions

void NutDelay (u_char ms)
 Loop for a specified number of milliseconds.
void Timer3Entry (void *arg)
 Timer 0 interrupt entry.
void NutRegisterTimer (void(*handler)(void *))
 Initialize system timer.
u_long NutGetCpuClock (void)
 Return the CPU clock in Hertz.
u_long NutGetTickClock (void)
 Return the number of system ticks per second.
u_long NutTimerMillisToTicks (u_long ms)
 Calculate system ticks for a given number of milliseconds.


Function Documentation

void NutDelay u_char  ms  ) 
 

Loop for a specified number of milliseconds.

This call will not release the CPU and will not switch to another thread. However, because of absent thread switching, this delay time is very exact.

Use NutSleep() to avoid blocking the CPU, if no exact timing is needed.

Parameters:
ms Delay time in milliseconds, maximum is 255.

void NutRegisterTimer void(*)(void *)  handler  ) 
 

Initialize system timer.

This function is automatically called by Nut/OS during system initialization.

Nut/OS uses on-chip timer 0 for its timer services. Applications should not modify any registers of this timer, but make use of the Nut/OS timer API. Timer 1 and timer 2 are available to applications.

Todo:
Hardware stuff to be put in nutlibdev.

u_long NutGetCpuClock void   ) 
 

Return the CPU clock in Hertz.

Returns:
CPU clock frequency in Hertz, which is 16780000 for the GBA.

u_long NutGetTickClock void   ) 
 

Return the number of system ticks per second.

Returns:
System tick frequency in Hertz.


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