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lpc2387 timer0 irq works only once

Ivan Kucherov

I'm trying to blink diode, using timer0 MR0 irq.
The problem is that the irq works only one time.
I see diode is just blinking once and nothing else.

I localized the issue and here's the code:

#include <lpc23xx.h>

void t0_irq() __irq
{
        if(T0IR&1)
        {
                T0IR=1;//reset irq
                if(FIO0PIN & (1<<9))  //if pin on
                {
                        FIO0CLR  = (1<<9); //pin off
                }
                else
                {
                        FIO0SET  = (1<<9);//else pin on
                }
        }
}

int main()
{
        //setup diode
        SCS |= 1; //enable FIO
        PINSEL0 &=~0x000C0000;
        FIO0DIR |= (1<<9);
        FIO0SET  = (1<<9);

        //setup timer0
        PCONP |= (1 << 1); // power up timer 0
        T0CTCR = 0;            // timer only mode */
        T0TCR = 0;                              // disable timer 0
        PCLKSEL1 &= ~0x0000000C;
        PCLKSEL0 |=  0x00000004;      // timer 0 clock = PCLCK
        T0IR = 0xFF;                    // reset irq flag
        T0PR = 0x00208D55;              // prescaler
        T0MR0 = 5;                      // match register 0

        // configure VIC
        VICIntEnClr |= (1 << 4);  // irq disabling
        VICIntSelect &= ~(1 << 4);// IRQ interrupt
        //VICVectPriority4 = 2;   // priority
        VICVectCntl4 =2;          // (i use old naming convention here)
        VICVectAddr4 = (unsigned long)&t0_irq;  // ISR address
        VICIntEnable |= (1 << 4); // irq enable

        T0MCR |= 0x03;            // irq and TC reset on MR0
        T0TCR = 0x01;             // start timer

        while(1)
        {
        }
}

Parents
  • 0

    Hi Ivan,

    I'm not familiar with the LPC2387, but I am very familiar with LPC214x parts, and I imagine some of the issues are the same. I have two observations :-

    1) Normally, with FastGPIO, it is necessary to unmask the relevant I/O Pins before you can use them. See the FIO0MASK register.

    2) Your interrupt handler doesn't appear to acknowledge the interrupt at the VIC. The consequences of this will vary depending on how your interrupts are configured but will generally either result in the interrupt handler only being called once, or it being called continuously.

    Hope this helps.

Reply
  • 0

    Hi Ivan,

    I'm not familiar with the LPC2387, but I am very familiar with LPC214x parts, and I imagine some of the issues are the same. I have two observations :-

    1) Normally, with FastGPIO, it is necessary to unmask the relevant I/O Pins before you can use them. See the FIO0MASK register.

    2) Your interrupt handler doesn't appear to acknowledge the interrupt at the VIC. The consequences of this will vary depending on how your interrupts are configured but will generally either result in the interrupt handler only being called once, or it being called continuously.

    Hope this helps.

Children