There are not enough hardware built-in PWM modules at these uC´s ( only 2 modules )
Also is not recomended implement that functionality by firmware, due precicion needed will increase Timer rate an all uC processing will be dedicated to this task.
If you need only 50-200Hz PWM this can easily be implemented in software. What PWM resolution are you looking for?
At this PWM frequency I am thinking about LED control. I have done 8 channels with a pseudo-logarithmic PWM signal (equivalent to ~13 bits resolution) on an ATtiny2313. PWM freq ~120Hz.
I have also done 32 channels with 8 bit resolution on ATmega163 running at <8MHz. PWM freq was >100Hz.
Of course the biggest problem when using SW for PWM is the delay caused by other things on the MCU. A simple I²C or UART interface for setting the PWM values can be done interleaved with the PWM generation.
You can take a look at this at it is a cheap PIC16 controller
Hope this helps.
Tahmid.
---------- Post added at 16:56 ---------- Previous post was at 16:55 ----------
At this PWM frequency I am thinking about LED control. I have done 8 channels with a pseudo-logarithmic PWM signal (equivalent to ~13 bits resolution) on an ATtiny2313. PWM freq ~120Hz.