HI,
Firstly, let's introduce my trial environment:
AM57xx A15 run Linux, and M4 run TI-RTOS, Linux will
display graphics, and M4 control GPIO pull up/down;
We use the the GPIO output 2ms PWM wave.
I have done some trial for this issue:
1. I use task_sleep in rtos side (M4 core) to sleep 1 ms and then reverse gpio。
When the graphics is not changed, the GPIO wave signal has no jitter. But when the graphics changed, it has a greater jitter! (100us-300us)
2, I use gptimer to make gpio generate the 2ms PWM wave,
and the phenomenon is same , that is , when the graphics is not changed, the GPIO wave signal has no jitter. But when the graphics changed, it has a greater jitter! (800us-900us)
I have done same trial on TI AM57xx GP EVM board, and has same phenomenon.
It seems that, when graphics changed, the clock system will have a greater jitter ?
About this CPU issue, please give me some proposal & solution !
Thank you very much!
Best Regards
Qing