[En-Nut-Discussion] Using the Periodic Interval Timer on the Ethernut 5 without Nut/OS

[Robin Leinauer]

Hello everyone,


I'm trying to use the Periodic Interval Timer on the Ethernut 5.0 F without Nut/OS.

I have set up the project according to the following guide: http://www.ethernut.de/de/hardware/enut3/noos.html.

This is my code:

//---------------------------------------------------------------------------------------------------------------------------------------

#include <toolchain.h>

#define MCK 90317000
#define LED_PIN 28

volatile unsigned int timer_ticks = 0;

void spurious_entry(void)__attribute__((naked));
void spurious_entry(void)
{
    IRQ_ENTRY();
    IRQ_EXIT();
}

void timer_tick(void)__attribute__((naked));
void timer_tick(void)
{
    IRQ_ENTRY();

    timer_ticks++;
    inr(PIT_PIVR);                                              // acknowledge timer interrupt

    IRQ_EXIT();
}

void init_timer(void)
{
    outr(PIT_MR, (MCK / (16 * 1000) - 1));

    outr(AIC_IDCR, _BV(SYSC_ID));                               // disable interrupt
    outr(AIC_SVR(SYSC_ID), (unsigned int)timer_tick);           // set interrupt handler
    outr(AIC_SMR(SYSC_ID), AIC_SRCTYPE_INT_LEVEL_SENSITIVE);    // define priority
    outr(AIC_ICCR, _BV(SYSC_ID));                               // clear interrupt

    outr(PIT_MR, inr(PIT_MR) | PIT_PITEN | PIT_PITIEN);         // enable timer and timer interrupt

    outr(AIC_IECR, _BV(SYSC_ID));                               // enable interrupt
    inr(PIT_PIVR);
}

void init_led(unsigned int pin)
{
    outr(PIOA_OER, _BV(pin));
    outr(PIOA_PER, _BV(pin));
}

void led_on(unsigned int pin)
{
    outr(PIOA_CODR, _BV(pin));
}

void led_off(unsigned int pin)
{
    outr(PIOA_SODR, _BV(pin));
}

void NutInit(void)
{
    outr(AIC_SPU, (unsigned int)spurious_entry);
    outr(AIC_IDCR, 0xffffffff);                                 // disable all interrupts
    outr(AIC_ICCR, 0xffffffff);                                 // clear all interrupts
    init_timer();
    init_led(LED_PIN);

    for(;;)
    {
        led_on(LED_PIN);
        if(timer_ticks > 0)break;
    }

    // is never reached
    led_off(LED_PIN);
    for(;;);
}
//---------------------------------------------------------------------------------------------------------------------------------------
Everything compiles without errors, but unfortunately the first for-loop never exited during execution, the led never turns off.
What am I doing wrong?
I'm using an Ethernut 5.0 F and loading the image via TFTP.


Thanks and best regards

Robin