Here is the Modified Firmware
It's basically missing the PLL entirely. I will caution however that use of this firmware is at your own risk. If vTune exceeds the absolute max of your VCOs, or attempts to tune too low, you can accidentally blow one or both of the VCOs out.
The tuning numbers for dcoffset and bandwidth are actually taken from the config page of the Wavebubble project. While these numbers aren't exact
, they're good enough for testing.
Again, use at your own risk. I'd recommend a few checks prior to using the code:
1. Verify the PWM test.
2. Verify the sawtooth High / Low test.
3. Verify the digital resistors test.
4. Ensure that you have attached D5 and D6 (protection to the VCOs) for going below ground.
5. Verify the switches tests.
6. Verify the output from the LM358s, that they are within range of your VCOs. (For this code).
(As a rule, this all should be performed before the VCOs are actually attached to the board).
Once everything checks out. You can attach the VCOs and wave guide wire antennas, and run the code.
: I should also point out that, if you are in posession of a spectrum analyzer, it's possible to build the WB without the PLL entirely, tuning would need to be performed by hand. A modified firmware like the one located above could be used, it could even be further modified for multiple programs.