AM4376: Precise time interval with linux kernel high resolution timer

Hello Piyush,

Please reference https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1262195/processor-sdk-am335x-how-to-make-a-accurate-timer-with-1-ms

Regards,

Nick

Hello Nick,

Thank you  for the reply, i read url links suggested by you, as per the e2e raised cases ,accurate timing can be achived through PRU, in my case we are already using PRU for Ethernet connectivity

Is it possible to use same pru to get 1msec tick to perform a dedicated task?

if so, please also suggest some documents to understand how to use/program  PRU for the required purpose.

Regards,

Piyush Ghatole

Hello Piyush,

No, if you are already using the PRU for Ethernet, that PRU is taken up already.

How are you doing your timeout intervals? For most Linux usecases I have found that the timers based on the Linux system timer are more than enough (instead of a dedicated hardware counter): check kernel APIs around add_timer() / mod_timer() / del_timer()

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1121806/processor-sdk-am64x-how-to-configure-ticks-in-linux/4161795#4161795

Regards,

Nick

Hello Nick,

we want to execute some activities in user space within fixed time interval, for the same i have started with usleep but unable to get it, then i wrote a high resolution timer kernel module with this also till 100msec i was able to get timing properly  but as i set time interval  10msec or 1 msec, i was not getting timing properly.

i understood for such need i have to use PRU but as it is already in use we can't use it, 

can you suggest any other way to achieve timing closer to my requirements?

regards,

Piyush Ghatole   

Hello Piyush,

Please take a look at the kernel APIs that I linked in my previous response:

like add_timer() / mod_timer() / del_timer()

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1121806/processor-sdk-am64x-how-to-configure-ticks-in-linux/4161795#4161795

usually those kernel APIs are sufficient, without needing to mess around with the hardware dmTimer instances.

Regards,

Nick