I have a PIC 16F628-20 micro running code to generate two dial tones.
It seems to be very fussy about how it is powered. Sometimes it starts on batteries, and sometimes not. On my lab supply, it puts out a steady PWM frequency, but with no modulation. Same goes with an LM7805. In all instances the voltage is 5V.
I don't think it is the PIC chip, since it will operate under what it perceives to be "ideal" conditions.
At present, I have only a 104 decoupling cap between the rail pins. That seems to be a general recommendation.
There must be some best practice thing I am overlooking with regard to making this reliable.
Can someone please point me in the right direction?
Robert Wade