Hi, I need to measure a pulse (see the image) so I config a TPM in capture mode, at the begin rising edge interrupt is active, when I enter in the ISR, falling edge interrupt is actived. When a falling edge comes I stay in the ISR for a certain delay (guard time) so I avoid to capture noise. But as soon as I exit from ISR a while after the ISR is called again. It is like there was a pending bit,but that's impossible because before to exit I reset the pending bit (TPM0_C0SC |= (0x80);). It doesn't happen if I disable the interrupt by TPM0_C0SC |= (0x40); but in theory it shouldn't be necessary and anyway interrupt flag keep on working.
What happening? Any idea?
Thank you very much
Hi again, I send you the true cases images.
Hi Ping, I send you two projects for frdm-kl25z (how send .rar??), the first generate 2 pulse on ptb2 pressing a button on ptb0, the second config ptc1 as input capture. Put breakpoints like in the picture. You are going to see the first stop on bkp B then on bkp A but in th is case you wont see any pending interrupt. Very very strange.
Hi Ping, I show you my pseudo-code:
TPM_ISR{
if((TPM0_C0SC & 0x4)){//if coming from a rising edge....
TPM0_CNT = 0X0;//reset counter
/* I'm not sure if that is correct,but the manual says:"When switching from one
channel mode to a different channel mode, the channel must first be disabled and this
must be acknowledged in the LPTPM counter clock domain." So I do this little code to switch from rising edge interrupt to falling edge interrupt.
If I don't do this, the code lose edges.
*/
TPM0_C0SC = 0x00U;
status = TPM0_C0SC;
while(status){
status = (TPM0_C0SC & 0x3C);
}
TPM0_C0SC |= 0x48;//falling edge interrupt enable
}else{//if coming from a falling edge
pulse_period = TPM0_CNT;//pulse measure
TPM0_C0SC = 0x00U;
status = TPM0_C0SC;
while(status){
status = (TPM0_C0SC & 0x3C);
}
TPM0_C0SC = (TPM_CnSC_CHIE_MASK | TPM_CnSC_ELSA_MASK);//rising edge interrupt enable
TPM0_CNT = 0;
counter = 0;
guard_time = 1000;
while(counter < guard_time){
counter = TPM0_CNT;
}
}
TPM0_C0SC |= (0x80);//reset interrupt flag
}//end TPM_ISR
As you can see, after the guard time I reset the possible pending (rising/falling)interrupt but as soon as I exit from ISR, the ISR is called again like there were a pending interrupt.
That happens only if the situation is like that showed in the image: two unwanted pulse; but if there is only one unwanted pulse all goes well. It is like in the guard time the pending interrupts were queued and TPM0_C0SC |= (0x80); only deletes one.
Only work if i disable interrupt by TPM0_C0SC &= (~0x40); before the guard time and then I re-enable it when guard time elapsed.
I'm getting crazy.
Thank you.
