DDS (generating sine waves) with onboard DAC using latest PIC 16F chips?

[HankMcSpank]

Well I did use a $1 MCU to generate that sine wave. So by your logic, that would be the right tool for the job.

Apologies...I misread you...if you paid a $1 (vs $15 for a DDS IC) & all you wanted was a 20Khz sine wave or less, then yes, by my logic that would be the right tool to do the job! (even if you had to dedicate the PIC to nothing else, due to the burden placed on it). They sell Aston Martins here in London...but I wouldn't buy one to go to the corner shop - my bike will do!

After just a short bit of dabbling, I've approximated a sine wave using DDS principles & the 16f1828's meagre inbuilt 5 bit DAC & a modest 16 bit accumulator (& no filtering cap),



Sure, the tops are a little pointy (16 levels per swing isn't much!) & I doubt it'll win any distortion/noise figure awards, but if I can squeeze another 2 bits resolution by getting creative with the FVR, then that'll probably do me. If not, I'll just go the 10 bit PWM method....but that method uses a filtering cap, so the amplitude will change with frequency - I was really after a fixed output amplitude no matter what the output frequency (& without going the R2R ladder way)

[rmteo]

Actually, the CPU load is zero while that $1 microcontroller is generating the 20KHz sine wave. You can just as easily generate any frequency up to about 250KHz with that device. Here is staircase waveform on the same MCU - great for doing things like testing power supplies, etc.