F28069 Timer interrupt

XINJUN DONG

I am new to the F28069 microcontroller. I am trying to use the cpu timer2 interrupt to control the epwm module. My pwm frequency is 500kHz. I would like it to generate 5 cycles and stop for 200 microseconds, and then generate another 5 cycles, and keep the same type of generating pwm signals.

Here is the code:

EALLOW;

PieVectTable.TINT2 = &cpu_timer2_isr;
EDIS;
ConfigCpuTimer(&CpuTimer2,80,10);///configure Timer2 @10 microseconds
StartTmr2();
IER |= M_INT14;
//Enable TINT0 in the PIE: Group 1 interrupt 7
PieCtrlRegs.PIEIER1.bit.INTx7 = 1;
EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM

Here is the interrupt routine:

interrupt void cpu_timer2_isr(void)
{
EPwm7Regs.CMPA.half.CMPA = 0;///Stop PWM by setting duty cycle to be 0
delayTime(200);///Wait for 200 micro seconds
EPwm7Regs.CMPA.half.CMPA = 80;///Restart PWM

}

My problem is that the code runs well, but the Timer2 does not trigger as I wish. It only generates 2 or 3 cycles each time. Does anyone have any idea about it? Thank you in advance.

Xinjun

over 13 years ago

0 Igor Gorbachev over 13 years ago

Guru 20525 points

Hello!

You set 10 us for timer interval and you use delay 200 us into ISR of this timer. There's something wrong.

Regards,

Igor

0 XINJUN DONG over 13 years ago in reply to Igor Gorbachev

Intellectual 300 points

Igor, Thank you for your reply. Actually, I am using timer2 to do the interrupt, but the delaytime function is using timer1. And I have checked that the delay function does not mess up the interrupt routine. Thank you.

0 Igor Gorbachev over 13 years ago in reply to XINJUN DONG

Guru 20525 points

Hi!

Well...You apply delay 200 us into ISR wich had to be called every 10 us. Where is the meanig? Maybe the timer2 should be programmed on interval >200 us? Or I don't understand something at your system?

Regards,

Igor

0 XINJUN DONG over 13 years ago in reply to Igor Gorbachev

Intellectual 300 points

Hi,

Because my code need to have 200us interval between two pwm bursts, that is the reason why I put a delay 200 us into ISR. But the burst is going to only last 10 us, so that is why I let the interrupt to be triggered at every 10 us. Thank you.

Xinjun

0 Igor Gorbachev over 13 years ago in reply to XINJUN DONG

Guru 20525 points

Hi!

How about this variant:

ConfigCpuTimer(&CpuTimer2,80,200);///configure Timer2 @200 microseconds

.......................................................................

uint16 flag = 1;

interrupt void cpu_timer2_isr(void)
{

if (flag) {EPwm7Regs.CMPA.half.CMPA = 0;///Stop PWM by setting duty cycle to be 0

flag = ~flag;

}

//////////////////delayTime(200);///Wait for 200 micro seconds

else {EPwm7Regs.CMPA.half.CMPA = 80;///Restart PWM

flag = ~flag;

}

Or is there something wrong?

Regards,

Igor

0 XINJUN DONG over 13 years ago in reply to Igor Gorbachev

Intellectual 300 points

Thank you, Igor.

If I am not wrong, the code is to turn on and off the pwm every 200us, which means that the time when it is on and off is 200 us equally. However, what I want to realize is to turn it on for 10 us and turn it of for 200 us. Thank you for your reply.

Xinjun

0 Igor Gorbachev over 13 years ago in reply to XINJUN DONG

Guru 20525 points

Hi!

Maybe:

ConfigCpuTimer(&CpuTimer2,80,210);///configure Timer2 @210 microseconds

.......................................................................

interrupt void cpu_timer2_isr(void)
{

EPwm7Regs.CMPA.half.CMPA = 0;///Stop PWM by setting duty cycle to be 0

delayTime(10);///Wait for 10 micro seconds

EPwm7Regs.CMPA.half.CMPA = 80;///Restart PWM

}

Thus 10us ON and 200us OFF.

Regards,

Igor

0 XINJUN DONG over 13 years ago in reply to Igor Gorbachev

Intellectual 300 points

That should be working. Thank you.

Xinjun

0 Igor Gorbachev over 13 years ago in reply to XINJUN DONG

Guru 20525 points

Hi!

Unfortunately long time I could not understand your desired waveform. If you could send a picture with your waveform I could think faster :)

Thanks, regards,

Igor

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F28069 Timer interrupt