You can get PWM "for free" if the code is complex enough that
there's somplace in it that gets visited at seemingly random
intervals. Just toggle the output bit at that point.



Also, does anyone know how long 4 AA batteries will power a
> grain of wheat bulb?  Many thanks in advance for any help you can provide.

No, but this can be determined in about 48 hours with 4 AA batteries
and a grain of wheat bulb.


--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html