Posted on May 17, 2011 at 13:58Hey Michael,
I've used the following code before to make a 32-bit capture by counting overflows and avoiding race conditions with the update (overflow) interrupt. Hope it helps.
void TIM4_IRQHandler (void)
{
u32 capture32;
static u32 ovf_ctr = 0;
if ((TIM4->SR & TIM_IT_CC1) && (TIM4->DIER & TIM_IT_CC1)) {
TIM4->SR &= ~TIM_IT_CC1;
capture32 = (ovf_ctr << 16) | TIM4->CCR1;
if ((TIM4->SR & TIM_IT_Update) && ((capture32 & 0x8000) == 0)) {
capture32 += 0x10000;
}
/* add processing code here */
}
if ((TIM4->SR & TIM_IT_CC2) && (TIM4->DIER & TIM_IT_CC2)) {
TIM4->SR &= ~TIM_IT_CC2;
capture32 = (ovf_ctr << 16) | TIM4->CCR2;
if ((TIM4->SR & TIM_IT_Update) && ((capture32 & 0x8000) == 0)) {
capture32 += 0x10000;
}
/* add processing code here */
}
if ((TIM4->SR & TIM_IT_Update) && (TIM4->DIER & TIM_IT_Update)) {
if (((TIM4->SR & TIM_IT_CC1) && (TIM4->DIER & TIM_IT_CC1)) ||
((TIM4->SR & TIM_IT_CC2) && (TIM4->DIER & TIM_IT_CC2)) ) {
/* do not process overflow if capture is still pending */
} else {
TIM2->SR = (u16)~TIM_IT_Update;
ovf_ctr++;
}
}
}
