Hi,
I am trying to do a basic use of interrupts with the AT91SAM7X256 board. As there are no LEDs in this board I am trying to turn on the Backlight of the LCD on and OFF every 1 sec using Timer Channel 1. But I have a problem with irq handler, I do not get the right asm code for the handler, can anyone help me with that please.
Thank you

This is a bit of a cut-n-paste job from a Keil app I had for the SAM7S. Not sure it helps here, but you request isn't specific about toolchains or GPIO ports. The IRQ/FIQ vectors jump to the AIC vector address.

// Keil AT91SAM7S-EK

#include <AT91SAM7S64.H> /* AT91SAMT7S64 definitions */
#include <lib_AT91SAM7S64.h>
#include "Board.h"

/*****************************************************************************/

#define TCK 1000 /* Timer Clock */

#define PIV ((MCK/TCK/16)-1) /* Periodic Interval Value (1ms)*/

/*****************************************************************************/

volatile unsigned long timeval; /* Current Time Tick */
int led_pit = 0;

/*****************************************************************************/

__irq void system_int (void) /* System Interrupt Handler */
{
if (*AT91C_PITC_PISR & AT91C_PITC_PITS) /* Check PIT Interrupt */
{
timeval++; /* Increment Time Tick */

if ((timeval % 500) == 0) /* 500ms Elapsed ? */
{
if (led_pit++ & 1)
*AT91C_PIOA_CODR = LED4;
else
*AT91C_PIOA_SODR = LED4;
}

*AT91C_AIC_ICCR = (1 << AT91C_ID_SYS); // Clear the SYS interrupt
*AT91C_AIC_EOICR = *AT91C_PITC_PIVR; /* Ack & End of Interrupt */
}
}

/*****************************************************************************/

void init_timer (void) /* Setup PIT with Interrupt */
{
AT91S_AIC * pAIC = AT91C_BASE_AIC;

*AT91C_PITC_PIMR = AT91C_PITC_PITIEN | /* PIT Interrupt Enable */
AT91C_PITC_PITEN | /* PIT Enable */
PIV; /* Periodic Interval Value */

*AT91C_PITC_PIVR += 0;

/* Setup System Interrupt Mode and Vector with Priority 7 and Enable it */
pAIC->AIC_SMR[AT91C_ID_SYS] = AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL | 7;
pAIC->AIC_SVR[AT91C_ID_SYS] = (unsigned long) system_int;
pAIC->AIC_ICCR = (1 << AT91C_ID_SYS); // Clear the SYS interrupt
pAIC->AIC_IECR = (1 << AT91C_ID_SYS); // Enable the SYS interrupt
}

/*****************************************************************************/

/*
* Main Program
*/

int main (void)
{
// Enable the Clock of the PIO
AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC, 1 << AT91C_ID_PIOA);

// Enable the Clock of the AIC & SYS
AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC, (1 << AT91C_ID_FIQ) | (1 << AT91C_ID_SYS));

// Configure the PIO Lines corresponding to LED1..LED4 as Outputs
AT91F_PIO_CfgOutput(AT91C_BASE_PIOA, LED_MASK);

// Clear the LED's. On the Board we must apply a "1" to turn off LEDs
AT91F_PIO_SetOutput(AT91C_BASE_PIOA, LED_MASK);

init_timer(); /* Initialize Timer */

// Loop forever
for (;;);
}

/*****************************************************************************/

Hi, thank you, but you gave a code to generate an interrupt through Periodic Timer, I want to do through the Timer Counters..