ARM Core A9 Tutorial | Basic CMSIS Example

#include <ARMCA9.h> // File name depends on device used

static const uint32_t TICK_RATE_HZ = 1000U;

uint32_t volatile msTicks; // Counter for millisecond Interval

static void SysTick_Handler( void )

{

msTicks++; // Increment Counter

}

// We use the Private Tiemer (PTIM) of the Cortex-A9 FVP Model here.

// In general the available Timers are highly vendor specific for Cortex-A processors.

void private_timer_init(void) {

PTIM_SetLoadValue ((SystemCoreClock/TICK_RATE_HZ) - 1U);

PTIM_SetControl (PTIM_GetControl() | 7U);

/* Install SysTick_Handler as the interrupt function for PTIM */

IRQ_SetHandler((IRQn_ID_t)PrivTimer_IRQn, SysTick_Handler);

/* Determine number of implemented priority bits */

IRQ_SetPriority ((IRQn_ID_t)PrivTimer_IRQn, IRQ_PRIORITY_Msk);

/* Set lowest priority -1 */

IRQ_SetPriority ((IRQn_ID_t)PrivTimer_IRQn, GIC_GetPriority((IRQn_ID_t)PrivTimer_IRQn)-1);

/* Enable IRQ */

IRQ_Enable ((IRQn_ID_t)PrivTimer_IRQn);

}

/* Delay execution for given amount of ticks */

void Delay(uint32_t ticks) {

uint32_t tgtTicks = msTicks + ticks; // target tick count to delay execution to

while (msTicks == tgtTicks) {

__WFE (); // Power-Down until next Event/Interrupt

}

}

/* main function */

int main(void)

{

/* Initialize device HAL here */

private_timer_init();

static uint8_t ledState = 0;

/* Infinite loop */

while (1)

{

/* Add application code here */

ledState = !ledState;

Delay(500);

}

}