Testing new cards

I'm testing the new cards that arrived this summer - in particular the digital voice card controller

Errors found

VCO: 

- Square wave is probably inverted, just like on the previous version of the waveshaper

To do

- Tune VCO

- Trim WS 

To test

- VCO frequency vs waveshaper and square wave generator, is the phase inverted?

- Lowest possible frequency for VCO, looks like trimming down won't go as low as DCOs?

- Recon-filter and wave output from digital board, including switching on the analog board

- Control pins on the digital board, though since midi works we know we can control everything. 

What works

- Distortion! :-D 

- Noise

- VCO waves in general

- WS wave mixing is now perfect 

- Midi input on digital card

- DCO tuning

- CV DAC control with 5V and 50MHz signal (3v3 also works but only at 40MHz)

- Rear soldered header on the Teensy 4.0 

- I2C port expanders 

- Winbond W25Q128 flash chip integration from Teensy. Not tested with DCO but uses same circuit. Was tested with W25Q128_test.ino (adapted from https://github.com/msnbrest/W25Q128)