I'm building a simple touch controlled pulse width modulator with a 12F615. Everything is working happily, except the hardware PWM frequency has a lower limit of about 245 Hz with the onboard 4 MHz clock. I need something between 100 Hz and 125 Hz.
-I don't have a spare pin to connect an external reference to drop the clock to 2 MHz.
-Using the ADC to detect touch is a time sensitive operation, so using the PWM overflow interrupt to load new values and hence extend the PWM cycle messes up the touch sensors.
-The software PWM is too low frequency, and simply writing to the pin is too slow, mostly because I have too much to do between state changes.
Does anyone have any ideas, or do I simply need to find a different part?
Even then... SW PWM seems to top out at a few 10's of Hz, while hardware PWMs bottom out about 250 Hz. Maybe dropping the clock speed (hence a package with more pins) is the ONLY answer?
Bookmarks