TMS320F28030: Timer0

Expert 1190 points

Part Number: TMS320F28030

Hi I'm new to the C2000,

I need to create a PWM waveform with a duty cycle of < 50 percent at a freq of 35khz

Using a PWM is not an option, which forces the use of a timer with a interrupt.

Is it possible to load timer counter with two different time periods (high/low) in the interrupt.

the sample code provided does not address the above, do you have something else available?

thanks

over 7 years ago

0 Veena Kamath over 7 years ago

TI__Mastermind 32655 points

Hi,

Yes. You can configure 2 timer interrupts and set the gpio pin high in one ISR and low in the other. But, this method may not be as efficient and accurate compared to using epwm modules. The software latencies of ISRs, presence of other interrupt may slight affect the duty cycle or period.
Usage of epwm is recommended since it is accurate and does not use any CPU cycles.

Regards,
Veena

0 Richard Poley over 7 years ago in reply to Veena Kamath

TI__Mastermind 27200 points

Just want to make you aware the F28030 has one eCAP unit which can be configured as an auxiliary PWM generator. If you're issue is simply that you've used all the ePWM modules, this may be a clean solution.

Regards,

Richard

0 jw over 7 years ago in reply to Richard Poley

Expert 1190 points

Does the eCAP require a external I/O for operation

0 Richard Poley over 7 years ago in reply to jw

TI__Mastermind 27200 points

Normally an eCAP would be associated with a single I/O pin: an input when configured in capture mode, or an output when configured as PWM generator.

Regards,

Richard

0 jw over 7 years ago in reply to Veena Kamath

Expert 1190 points

Rather than a ISR routine, can the ISR flag be poll in main, if so how?

0 Richard Poley over 7 years ago in reply to jw

TI__Mastermind 27200 points

Yes. For example, for CPU timer 0 you'll check the status of the TIF flag (bit 15 in register TIMER0TCR) in your idle loop. When TIF is '1', you run your code and then write a '1' back to it to clear the flag. We don't have example code for anything like this.

As Veena pointed out, the method is not going to be efficient or accurate. You may expect jitter on the generated PWM timing.

Regards,

Richard

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28030: Timer0