08-17-2017, 02:49 AM
Good day
I am looking to verify my understand of the timing of the push-pull PWM mode of the dsPIC30F1010.
I am looking to have the pulse width incremental by 50ns. From my understanding this would equate to Fosc of 1.25MHz. 50ns = 1/(1.25MHz x 8 x 2). Eight being the frequency divider after the PLL and two being used since the input the PWM module is effectively doubled in frequency due to the clocking using the rising and falling edge for counting? Does this thinking make sense?
I calculate a maximum period of 3.2768ms. (2^13) x 400ns - The timers frequency being four times Fcy? ("Period Duration = (PTPER + 1)/120 MHz @ 30 MIPS") - from the data sheet - bottom of page 125.
Is this correct? I have some confusion since in the data sheet on page 126 it is said that, "The PWM time base counters are 13 bits wide and increment twice per instruction cycle." The instruction cycle with Fosc being 1.25MHz would be 1.6us, meaning there are 4 counts in one instruction cycle?
My issue, if I am correct, is that I require the push-pull PWM mode with a minimum period of 10ms without increasing the pulse width increment of 50ns.
Is there a PS PWM module with push-pull mode out there that can provide this functionality? Or can someone point me in the right direction of a work around to effectively create such a module?
Many thanks