TMS320F28388D: ePWM module clocking

Ivan Sykorka

Part Number: TMS320F28388D

Hi, I have question about clocking of ePWM modules of TMS320F28388D device.

Im using the General Purpose Timer0 (UP - count mode) and ePWM2 (UP/DOWN - count mode) module.

All CLOCK dividers and prescallers are set to "/1". System CLOCK frequency is 200 MHz.

Timer0 - period is set to 40000. Timer0 period ISR is occured every 200 microseconds (40000 / Fcpu = 40000 / 200000000 = 0.0002s).

To reach same period on ePWM2 TIM=ZERO ISR I must set value EPwm2Regs.TBPRD = 10000. It´s clear, that ePWM is working on base frequency 100MHz.

I toggle GPIO testpins in Timer0Period_ISR and ePWM2Zero_ISR. On oscilloscope test these testpins change their levels with same period 0.0002 sec.

MY QUESTION :

Why can´t I configure ePWM2 module to operate at same Base frequency as Timer0 ? I expext EPwm2Regs.TBPRD = 20000 as half of value CpuTimer0Regs.PRD.all.

Is it possible configure ePWM2 module to operate at no-divided maximal CPU CLOCK 200MHz? I will minimize the ePWM2 pulses grannularity and maximize resolution of PWM.

Thanks and Im waiting for Your answer !

over 3 years ago

0 Nima Eskandari over 3 years ago

TI__Guru 52040 points

EPWM counter is in what mode?

0 Ivan Sykorka over 3 years ago

Prodigy 20 points

Hello Nima,

Thank you. I wrote it, but repeat it here again:

Im using the General Purpose Timer0 (UP - count mode) and ePWM2 (UP/DOWN - count mode) module.

Next link contain screenshot of my actual ePWM2 configuration :

CCSV11 - NXC_RU/Matlab_SRC/nxc_ru_ert_rtw/ert_main.c - Code Composer Studio (gyazo.com) .

I generate code using MATLAB R2021b with latest CGT and Target Support Package for TI C2000. I use Code Composer Studio ver. 11.

Have a nice day !

0 Nima Eskandari over 3 years ago in reply to Ivan Sykorka

TI__Guru 52040 points

Well you are using UP-DOWN count mode. It should be expected that it's halved!

Nima

0 Ivan Sykorka over 3 years ago in reply to Nima Eskandari

Prodigy 20 points

I'm sorry, I guess I didn't say exactly what the problem was?

If the peripherals TIMER0 and ePWM2 are working with same base frequency, it is normal that ePWM_period register (in UP/DOWN-COUNT mode) need half of TIMER0 period register in UP-COUNT mode. But in my project I must set the ePWM period to quarter value of TIMER0PRD (TIMER0PRD/4).

It looks like the ePWM module is operating at half the clock frequency as TIMER0. Since I have all CLOCK dividers set to / 1. The question is, why is that?

0 Nima Eskandari over 3 years ago in reply to Ivan Sykorka

TI__Guru 52040 points

EPWM will count from 0 to PRD then back down to 0 and that is ONE-CYCLE.

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28388D: ePWM module clocking