Quote Originally Posted by HankMcSpank View Post
My first (present) plan of attack is to use the 5 bit internal DAC to get an anlogue output... (that's what my screenscrape was earlier - using the PIC's internal DAC to get a rough analogue output) clearly 32 steps is insufficent for sine waves, so I was trying to add an extra 2 bits by creatively using the PIC Fixed voltage reference (the PIC FVR output canfeed the DAC and the voltagae output can be set to 1.024V, 2.048V or 4.096V) - I might not be grasping a fundamental issue here, so I need to ponder this one until I have an "Oops, that was an embarrassing idea" moment!
Well, I reckon this one is doomed ...I've only just realised for my plan to work, I would need to be able to shift the 'negative ref' of the DAC to the FVR module output (I'd then get 32 steps between gnd & FVR ref, then another 32 steps between FVR & Vref) - the 16f1828 DAC control register doesn't allow this...hey ho.

Ok, so HPWM and a filter it is then...at least I'll see what impact there is on amplitude as the frequency rises!