First post, by Shamatic
First time poster, long time lurker here.
The reason I'm posting here is because I've been working on a project that might spark your interest.
Background: So, on a long night I was looking at some old schematics about a PWM Covox implemented in TTL and an idea struck me that an Atmega328 would totally capable to do the same thing and more. And it seemed to be an easy thing to implement. Since I had some Pro Minis at hand, I started to work on it almost right away (I mean in a few days). Now that easy thing turned me to learn AVR assembly (I had no assembly knowledge before at all) to control as much aspect of the MCU as possible to make this contraption work. I hope you think I succeeded my task.
Here is a photo of the completed device:
This thing has a lot going for it:
- It's the simplest and the cheapest in it's category, only a few parts to build. And also the smallest, as the whole design can fit in an LPT connector housing.
- Fully working DSS with proper auto-detection support. (Tested in Wolfenstein 3D, Alone in the Dark, Dungeon Master.)
- Stereo-in-1 mode supporting multiple kinds of signaling modes. (Tested to work with Inertia Player, ModPlay Pro, Dual Module Player, Galaxy Music Player and Crystal Dreams.)
- Mono Covox plays on both channels.
- Fully automatic, properly switches to the exact state it needs to be, no matter what garbage others leave on the LPT's control port.
- MCU code is written in AVR Assembly, uses 266 bytes of flash and 16 bytes of ram (for the DSS fifo buffer) and it's interrupt driven.
Hereby I attach a package of code and instructions if you wish to build it yourself and give it a test run. I would appreciate any feedback if you did.
PS: I know this setup has it's limits in the sound quality department, but I'm already contemplating about porting this code to the STM32 bluepill, which has I2S output, can be programmed on the low level, not to mention being faster. Also (as far as I know) it has enough ports to emulate a dual lpt setup too, so that would be some added bonus too. Sadly my only Bluepill is in my homemade Unamiga clone, so this will have to wait until I order some, and have both the motivation and the time to do the porting. (This can amount to a surpisingly long amount of time, as I'm lazy.)
Edit: Fixed the bug of Modplay and Galaxy Player is playing in reverse
