I've come across another related oscillator, also the chip is from AD (Analogue Devices) an AD9833. As a module (from Banggood etc.) its maximum frequency is 12.5MHz but its frequency increment is a more human-friendly 0.1Hz. It's simpler to interface as well as being somewhat cheaper than the AD9850/AD9851 modules mentioned previously.
The downside to the AD9833 is it can only generate one type of waveform at a time, not sine and square simultaneously, though there is a triangle waveform making a third choice...not sure how useful that would be though... I would call it sawtooth rather than triangular.
That would suit me fine so I'm considering doing the AD9850 version as described so far in this thread, and a AD9833 variant later. Except for the module I think the rest of the circuit will be virtually identical...with lower power consumption. However the PIC16F833 software would need to be different, not sure if there's enough program space to provide both versions on one PIC16F833. (14-pin DIP).
- AD9833 Module.jpg (8.7 KiB) Viewed 10554 times
The SMA connector can be unsoldered if you don't need it.
Steve A.
The 0.1Hz increment value mentioned is wrong, it's 0.0931...(get your calculator out), so with that I don't see any point in going further...shame when someone tries that game on...25MHz/2^28=0.0931...specmanship...I admit I had my doubts as I started to read the datasheet...to get a 0.1Hz increment value the crystal would need to be 26.864Mhz which is outside the specifications (7.3% high) though
most would work there's a chance it may not, and it's not a common crystal/oscillator frequency anyway.
The datasheet for the AD9833 is attached...