Urgent: Problem in Timer interrupt program using AT91SAM7SE512-EK]

Hi Martin,

This is what i did in the code

void timer0_c_irq_handler(void)
{
AT91PS_TC TC_pt = AT91C_BASE_TC0;
 unsigned int dummy;
 dummy = TC_pt->TC_SR;
 dummy = dummy;
if ( (AT91F_PIO_GetInput(AT91D_BASE_PIO_LED) & AT91B_LED1 ) == AT91B_LED1 )
{
 AT91F_PIO_ClearOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
}
else
{
AT91F_PIO_SetOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
}

AT91F_AIC_AcknowledgeIt (AT91C_BASE_AIC);
}

With regards,
Murthy.R

Hi Martin,

This is what i did in the code

void timer0_c_irq_handler(void)
{
AT91PS_TC TC_pt = AT91C_BASE_TC0;
 unsigned int dummy;
 dummy = TC_pt->TC_SR;
 dummy = dummy;
if ( (AT91F_PIO_GetInput(AT91D_BASE_PIO_LED) & AT91B_LED1 ) == AT91B_LED1 )
{
 AT91F_PIO_ClearOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
}
else
{
AT91F_PIO_SetOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
}

AT91F_AIC_AcknowledgeIt (AT91C_BASE_AIC);
}

With regards,
Murthy.R

Is that how you actually write your code?

Do you find it clear and easy to read?

Most people find it helps to use indentation and whitespace to lay-out their code for easier reading; eg,

void timer0_c_irq_handler(void)
{
   AT91PS_TC    TC_pt = AT91C_BASE_TC0;
   unsigned int dummy;

   dummy = TC_pt->TC_SR;
   dummy = dummy;

   if( ( AT91F_PIO_GetInput(AT91D_BASE_PIO_LED) & AT91B_LED1 )
       == AT91B_LED1 )
   {
      AT91F_PIO_ClearOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
   }
   else
   {
      AT91F_PIO_SetOutput( AT91D_BASE_PIO_LED, AT91B_LED1|AT91B_LED2 );
   }

   AT91F_AIC_AcknowledgeIt( AT91C_BASE_AIC );
}

Doing complex operations inside the 'if' like that doesn't help readability, and making a separate assignment is unlikely to affect performance...

Hello Nanju Murthy,

Please use the keyword volatile for the definition of your dummy variable.

 volatile unsigned int dummy;
 dummy = TC_pt->TC_SR;
 dummy = dummy;

volatile tells the compiler that the varible can be modified externally to the implementation.

Best Regards,
Martin

HI Martin,
I have tried this volatile also the result is same.
here by i have enclosed the initialization code.
Is there any wrong please check and advise me.

void timer_init ( void )
{
AT91F_TC_Open(AT91C_BASE_TC0,TC_CLKS_MCK1024,AT91C_ID_TC0);

AT91F_AIC_ConfigureIt ( AT91C_BASE_AIC,
                                AT91C_ID_TC0,
                                TIMER0_INTERRUPT_LEVEL,
                                AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL,
                                timer0_c_irq_handler);

     AT91C_BASE_TC0->TC_IER = AT91C_TC_CPCS;
     AT91F_AIC_EnableIt (AT91C_BASE_AIC, AT91C_ID_TC0);


     AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG ;


}

With regards,
Murthy.

Hello Murthy,

I have no idea what is going wrong.

Did you test the timer in polling mode?
Do not enable the interrupt and check the TC Status register in a loop to see whether the compare flag is set.
Is the clock for the Timer enabled and working?
Check the CLKSTA bit in the TC Status register.
Maybe it is a good idea to check the ATMEL website to see if there is an example for a timer using interrupts.

Best Regards,
Martin

Hi Martin,

Thanks for your suggestion.

I have tested the timer in polling mode.
without enable the interrupt and checked.
The TC Status register the compare flag is set.
The clock for the Timer enabled and working.

I have one doubt
"should i include any IRQ0.s files in my project?"

If necessary means please give me the downloaded links.

Please advise me on this.

with regards,
Murthy.R

Hello Murthy,

I think you do not need the IRQ0.s file for you Timer Interrupt.
Is the peripheral clock for the timer enabled?
Check PMC_PCER register (see AT91SAM7SE512 user manuel chapter "Power Management Controller (PMC) User Interface").

You wrote that the timer interrupt occurs only once. That means, that the interrupt is not acknowledged anyhow.

Please check your interrupt service routine that the following things are done:
- clear interrupt in AIC Interrupt Clear command register
- read Timer Status register (clearing interrupt reason)
- acknowledge interrupt by writing to AIC End of Interrupt Command Register

Best Regards,
Martin

Hi Martin,
i have checked the PMC for timer,that is enabled.

I have a startup code "SAM7.s"
In this file some configuration settings are there.

Q1.Do i have to make any changes on this STACK settings?

I have installed the KEIL in "C:/KEIL"folder.
and also installed the patch file in the same folder.

Q2.Is this installation procedure correct?

Please advise me on this.

with regards,
Murthy.R

Hello Murthy,

I do not know which patch file you mean.

Take the example C:\Keil\ARM\Boards\Atmel\AT91SAM7SE-EK\Blinky and replace Blinky.c
with the following code and you have a Timer0 interrupt which ticks every 10ms.

#include <AT91SAM7SE512.H>              // AT91SAM7SE512 definitions
#include <lib_AT91SAM7SE512.h>          // AT91SAM7SE512 library functions
#include "../AT91SAM7SE-EK.h"           // AT91SAM7SE-EK board definitions

unsigned int led = 0;

// Timer0 ISR
void tim0_isr (void) __irq {
static int msCnt = 0;

  if (msCnt++ > 10) {                                     // switch LED every 100ms
    msCnt = 0;
    if ((led ^=1) == 0)
      AT91F_PIO_ClearOutput(AT91C_BASE_PIOA, AT91B_LED1); // LED on
    else
      AT91F_PIO_SetOutput  (AT91C_BASE_PIOA, AT91B_LED1); // LED off
    }

  AT91C_BASE_AIC->AIC_EOICR = AT91C_BASE_TC0->TC_SR;      //  Interrupt Ack
  AT91C_BASE_AIC->AIC_ICCR  = (1 << AT91C_ID_TC0);        //  Interrupt Ack

  *AT91C_AIC_EOICR = 0;                                   // End of Interrupt
}

// Main Program
int main (void) {

  AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC, 1 << AT91C_ID_PIOB); // Enable Clock for PIO
  AT91F_PIO_CfgOutput(AT91C_BASE_PIOA, AT91B_LED_MASK);            // PIO for LEDs as Output
  AT91F_PIO_SetOutput(AT91C_BASE_PIOA, AT91B_LED_MASK);            // turn off LEDs

  AT91F_PMC_EnablePeriphClock(AT91C_BASE_PMC, 1 << AT91C_ID_TC0);  // Enable Clock for TIM0
  AT91C_BASE_TC0->TC_CCR    = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
  AT91C_BASE_TC0->TC_CMR    = 2 | AT91C_TC_CPCTRG;
  AT91C_BASE_TC0->TC_RC     = 14975;                                        // period is 10ms
  AT91C_BASE_TC0->TC_IER    = AT91C_TC_CPCS;

  // TIM0 Interrupt: Mode and Vector with Lowest Priority and Enable */
  AT91C_BASE_AIC->AIC_SMR[AT91C_ID_TC0] = AT91C_AIC_SRCTYPE_INT_POSITIVE_EDGE | AT91C_AIC_PRIOR_HIGHEST;
  AT91C_BASE_AIC->AIC_SVR[AT91C_ID_TC0] = (unsigned long) tim0_isr;
  AT91C_BASE_AIC->AIC_IECR = (1 << AT91C_ID_TC0);

  while (1);                                                       // Loop forever
}

Best Regards,
Martin

Hi Martin,

Lot of thanks for your example code.

I have checked the code in the blinky project,the timer interrupt is working.

I have one doubt,

In your code you did't enable the Peripheral Clock for PIOA, But you are using the PIOA for LED.

Q1.Without Enable the Peripheral Clock for PIOA how it is working?

Please advise me on this.

With regards&Thanks
Murthy.R