Last week I released Parva Mainboard Firmware v0.50, which included a wide range of bug fixes, improvements, and added features. Most significantly, I was able to resolve the relative tuning issue through the mainboard firmware; however, some of the other fixes and features require new voicecard firmware.
Unlike the mainboard, the new voicecard firmware didn’t require a full rewrite, but there are some significant changes in the DCO code to eliminate popping/crackling noises and the aliasing that can be heard when playing high notes. This new code is fully tested and almost ready for release. The one remaining issue is the ramp control calibration function.
Some of you have noticed the inconsistent oscillator levels, PWM widths, and glitchy triangle waves – all of these are caused by inconsistent ramp core trimming. Fortunately, each voice card contains circuitry to route signals back to the master microcontroller, which can then automatically re-calibrate the ramp cores. I’m fine-tuning the calibration code right now, and hope to have it working tonight, but it is a fairly complex and tedious process.