Analog Audio Demo

A project log for Propeller S/PDIF Receiver

Uncovering Subchannel Secrets

Jac GoudsmitJac Goudsmit 06/18/2017 at 08:120 Comments

What's this, another change to the hardware? Well... Yes and no. I like the new Parallax FLiP for breadboard development but I wanted to do something today that actually makes the S/PDIF decoder do something that's (arguably) useful, so I connected a QuickStart board with a Human Interface Board for the Quickstart. The HIB board has filters and a connector to connect stereo headphones (just like the Propeller Demo board, by the way) and I wanted to write a small module that just grabs samples from the Biphase decoder and sends them to the headphones.

It took me a while to get it to work, because apparently I had made a mistake and passed the pointer to a parameter variable (which was already a pointer) instead of passing the parameter directly.

Because of this, I now have a sort-of sanity check that lets me know that the biphase data is decoded and processed correctly (well... at least the audio part of the subframes).

The next step will be to change the Biphase decoder to write the data into a buffer instead of a single long word. This should come in useful for extracting subchannel data. And that's what this project is all about.