While Loop wait Interrupt Handler

Question

I'm writing a C program to program a microcontroller. In practice, when an interrupt handler occurs I go to execute the following code:

uint8_t call_irq_handler = 0; // variable that is modified by the irq handler
uint8_t call_irq_handler_previous = 0;

static __attribute__((interrupt)) void __irq_handler()
{
    call_irq_handler_previous = call_irq_handler;
    call_irq_handler = call_irq_handler + 1;
}

In main, instead, to wait for the interrupt handler to be executed, I put the following while loop:

while (call_irq_handler == call_irq_handler_previous)
{
    count_cmd_write++;
#if DEBUG
    printf("...i didn't get interrupt handler for cmd_write...\n");
#else
    continue;
#endif
}

If I set DEBUG 1, I have no problem, the code is executed and after a while I exit the while loop. However, if DEBUG 0 then I remain in the while, and therefore the interrupt handler is not taken. Anyone know why this happens?

Duplicate: electronics.stackexchange.com/questions/409545/… — Lundin
– Lundin, Commented Oct 16, 2021 at 20:04

Dooraim · Accepted Answer · 2021-10-16 14:40:34Z

1

I solved the problem by going to insert volatile

 volatile uint8_t call_irq_handler = 0; // variable that is modified by the irq handler
        volatile uint8_t call_irq_handler_previous = 0;

answered Oct 16, 2021 at 14:40

Dooraim

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