Alain,

The traces were from the 12f675 that used A/D to read the voltage from a 10K pot (as detailed in post #22).

Code:
ADCIN 0, D                                   
    Pwm GPIO.2,D,1
goto main
I was expecting a traditional square wave type signal, with varying width of pulse, not the noisy signal the PIC is outputing.... The manual shows additional components for analogue output (resistor / capacitor), maybe I should try using that to get a decent signal out ?