TMS320F28379D: HRPWM jitter

Lukas Brzyszkiewicz

Intellectual 335 points

Part Number: TMS320F28379D

Hi,

what is acceptable jitter of PWM when HRPMW is enabled?

After some tests I have (generate 25600Hz clock divided by 512 to get 50Hz signal):

- HRPWM off - about 450uHz

- HRPWM on HRCNFG.EDGMODE 0 - 7000uHz

- HRPWM on HRCNFG.EDGMODE 1 - 13500uHz

- HRPWM on HRCNFG.EDGMODE 2 - 7000uHz

- HRPWM on HRCNFG.EDGMODE 3 - 13500uHz

I have only TBPRD:HR register set because I need to set fractional TBPRD value.

Is this correct behaviour of HRPWM? Afcourse mean value is valid but output signal has more jitter than without HRPWM.

over 7 years ago

0 Lukas Brzyszkiewicz over 7 years ago

Intellectual 335 points

OK,

I found answer for my problem.

I think this post is very importnat and datasheet of all HRPWM enabled devices should be modified:

TMS320F28075: HRPWM anomaly under certain conditions - C2000 microcontrollers forum - C2000™︎ microcontrollers...

e2e.ti.com

Part Number: TMS320F28075 Other Parts Discussed in Thread: TMS320F28035 Hi everyone, I'm encountering a problem with HRPWM similar to the one mentioned in this

Very important thing that you must modify HRLOAD register to selected EDGMODE. I think this is misunderstund, because I was thinking that HRLOAD is only for loading from shadow register to active register of value that I modifiy, but this isn't true by 100%. True purpose of this setting is to tell when to load new HR value regarding to working MEP module.

I think that datasheet should be updated to bo more clear about HRPWM module - informations about configuration and working of HRPWM module (and connections, etc.) are not fully understendable and valid/clear.

0 Nima Eskandari over 7 years ago in reply to Lukas Brzyszkiewicz

TI__Guru 52020 points

I will make a note of this to see how to make it more clear. Thank you!