post #8Originally Posted by rmteo
|
post #8
|
OK, here is a brain teaser for you. With an 8MHz clock on a PIC16/18, what is the maximum frequency HPWM that can be achieved, and how would you do it (in terms of register values for CCPR1L and PR2)?
Hint: the answer is in the scope trace above.
|
Can't see the 'scope trace here (server won't let the image thru)...
In the absense of any other information (PIC type, CCP or ECCP, not that it matters), I would guess 1Mhz...
8Mhz / 4 ( crystal vs. Fosc) = 2 Mhz, but still need another cycle to set and/or reset the outputs in the CCP module, hence 1Mhz. Again, don't have enough info, nor datasheets handy.
|
Ski, you hit the nail on the head, 1MHz it is. I tested it in hardware and looked at the scope. It would apply to any PIC12/16/18 with either CCP or ECCP at 8MHz clock. You could get 2MHz (fFOsc) out of CLKO though.
BTW, the settings would be:
PR2 = 1
CCPR1L = 1
|
thanx everyone.i can get 332khz with 50% duty cycle using OSC 20MHz...
|
Amazing as it seems, you can generate a 2MHz PWM with an 8MHz clock. Not only that but you also get 2-bit resolution (4 duty cycles).
|
Using the 4xPLL is cheating!
|
No PLL used, just 8MHz clock.
|
k, I give. how you plan on doing that?No PLL used, just 8MHz clock.
0%, 100%, spikey 1% and spikey 99%?
|
mea culpa.post #8
Members who have read this thread : 0You do not have permission to view the list of names.
Posting Permissions
Bookmarks