8-bit MicrocontrollersのトピックRe: Delay in ms function

Delay in ms function

Skaptor — Sat, 03 Sep 2011 22:59:09 GMT

Hello,

I´m developing a delay function that works in milliseconds.

this is my code so far:

void delayms(unsigned int time)
{
result1 = max_value / 1000;

final_result = result1 * time;

d_enabled = FALSE;

if(!d_enabled)
{
    dmsec     = 0;
    TPM2MOD   = final_result;
    TPM2SC    = 0x0F;
    TPM2C0SC = 0x54;
    TPM2C1SC = 0x10;
    d_enabled = TRUE;
}

while(!delay_done);
}

Here´s the TPM_ISR

interrupt VectorNumber_Vtpm2ch0 void timer2_CH0(void)
{

// Clear CH0F flag
TPM2C0SC &=0x7F;

    dmsec++;

    if(dmsec == final_result)
    {
      TPM2MOD = 0;
      TPM2SC   = 0x00;
      TPM2C0SC = 0x00;
      TPM2C1SC = 0x00;
      delay_done = TRUE;
    }


//Clear the 16-bit timer1 counter
//TPM1CNTH = 0x00;

}

My timer counts at 1 second with a MOD equal to 0xFF ot 65535 so basically assigns the MOD value to a fixed one depending on the function call.

My problem is, with that while it seems the timer ISR is not working, so I´m looking for a way to loop inside the function until the timer returns a flag?.

Re: Delay in ms function

bigmac — Thu, 29 Oct 2020 09:11:05 GMT

Hello,

I cannot understand your reasoning for changing the modulo value from free-running mode, or for the use of a TPM prescale setting of 128. Both would seem quite unnecessary. Additionally, you seem to have a channel setting to toggle on output compare. You actually require software compare mode for this application.

Basically you require that a channel interrupt occurs every millisecond, by using software output compare mode for the TPM channel. When each interrupt occurs, I prefer to decrement the 'dmsec' counter, so that when timeout is reached the counter value will be zero, and further counting is inhibited. No other timeout flags would be necessary.

#define INCRVAL  4000           // Value for 1ms increment    // assuming 4MHz bus, prescale 1// Global variable:volatile word dmsec;/*************************************************************************/// Initialisation for TPM2 modulevoid TPM2_init( void){   TPM2MOD  = 0;                // Free-running mode   TPM2SC   = 0x08;             // Bus clock source, prescale 1   TPM2C0SC = 0x00;  // Channel 0 initially disabled}/*************************************************************************/// Set delay timeout period (multiples of 1ms)void setdelay_ms( word time){   __asm sei;                   // Disable interrupts   TPM2C0V = TPM2CNT + INCRVAL; // First compare value   dmsec = time;   TPM2C0SC = 0x50;             // Software compare mode, interrupt enabled   TPM2C0SC_CH0F = 0;           // Ensure flag is clear   __asm cli;                   // Enable interrupts}/*************************************************************************/// Wait for delay timeout periodvoid waitdelay_ms( word time){   setdelay_ms( time);   while (dmsec)           // Wait for timeout      __RESET_WATCHDOG();}/*************************************************************************/// ISR for TPM2 channel 0interrupt void ISR_TPM2C0( void){   TPM2C0SC_CH0F = 0;           // Clear flag      TPM2C0V += INCRVAL;          // Next compare value   if (dmsec) {      dmsec--;      if (dmsec == 0)         TPM2C0SC = 0x00;       // Disable further TPM2C0 interrupts   }}

Regards,

Mac

Re: Delay in ms function

Skaptor — Sun, 04 Sep 2011 05:34:46 GMT

Thank you very much, the only thing I had to do was, the incrval was 4000 so it was giving me a 336ms pulse, so I just multiplied, divided and changed the INCRVAL to a fixed value. Now it gives me the correct amount of ms.

Regards.