8 bit vcdo

VCDO update: delay tables

Submitted by John on Mon, 06/29/2020 - 20:27

This weekend I spent quite a bit of time working on re-writing my delay table generator. 

The 8 bit VCDO generates an audio signal by spitting out each sample of a waveform, one at a time. I do not use a timer on the chip to achieve this (maybe I should have). Instead, I manually track how many processor cycles take place every time I go through the main loop. Depending on what pitch I am trying to achieve, I delay a specified number of processor cycles (fetched from a lookup table) before moving on with the loop. 

Made progress with my analog filter

Submitted by John on Mon, 09/09/2019 - 22:41

Tonight I finally got my first prototype filter mocked up for the 8 bit VCO. Okay, technically that's not true, I've made four separate output filters so far. But they've all had problems one way or another.

The first one, a passive filter, was just too rough. Second one was alright but I lost my paper with the component values on it. Easier to just design it all over again.