Monday, April 27, 2020

The History of the Sidbox

sidbox0.jpgThe day I began to play with the microcontrollers was fun and interesting, from just turning on motors to lighting up LED’s.

While these where fun and I did make some pretty cool devices, such as a home automation. I began to yern for things like audio.

In the end I learned what I could get my hands on, and one day while listening to good old Sid tunes with Sidplay.exe, I thought, I’d love to hear this stuff on a chip, instant ON battery powered SIDPlay.

I created my own audio Sidchip with 8 channels, but it was fairly basic, didnt’ have Ring mod, PWM controls… So I desperately looked into how the C64 played its chip tunes and I found it was a lot more involved than I initially thought… As a result I slumped and almost gave up, after about a year I decided to have another go.

Starting with the need for the 6502 Core, and I wrote a small program on it and found that the core did work, the CORE emulation worked on a PIC MCU running on a 40Mhz chip!

So I proceeded to learn about the SID 8582 (it was the only chip I physically had) and begin to learn how this bird sang.

After MONTHS of tearing hair our, punching walls and crying, I got a sidchip working, but it wasn’t enough, the SIDCHIP worked in my c64, but i wanted to have it independently PLAY music from the MCU it self, that required the CPU emulation also, which sadly the 40Mhz MCU worked well enough to produce a very very low quality sid noise

Upgrading from an 8BIT MCU i used the dsPIC24, 16bit running at 70Mhz which MADE alot of difference, and built this…

This little device did everything I needed, so I added a very basic file system FAT16 to it, and would only read ONE file on the root, but it loaded that sid tune into its small ram, 32K (so only a small sid file was allowed, 1k) and more programming time was thrown into this.

It picked up the file and BADLY played the SID tune, BUT it gave it a go.
After many more weeks of figuring out whats going on, was a stupid signed char, not a unsigned char that made the difference…
Gates worked, pitch and audio stepping and phase worked!

this chip could only produce a small 22khz output but it was more than good enough for tiny speakers.

I started to think this was IT, a portable SID player! instant on, ready to go in a second and playing music! (greating cards anyone?)

sidbox_start.jpgI wonder if I could make a 4 channel amiga MOD play on this, there wasn’t enough memory to perform this action here, so I upgraded to another dsPIC33 which had 512k Rom, and 128k Ram,

THEN this little machine was born

this was the very very first sidbox made, it had no volume control nor a DAC, it was purely done with an amp, the TDA2822 with a PWM source in, wow the pure clean sound (lol) it was grainy and alot of electrical noise appeared on this amp too! no filtering (since I was still researching how to do this)

I used this for a few days, before I began to really redesign the mainboard, this has a volume control and much better noise handling however the PCB still was a 2 layer board so all the signal and power rails where all mixed up on the 2 layers, yupp that was a rookie mistake right there…

sidbox3.jpg

still this unit and I got on with each other for just a year.

Then microchip sent me a sample chip, just turned up at the door and I thought, ok I’ll see what this does…

THAT was the PIC32MZ that we all know and love today!

pic32mz.jpg

it currently runs our sidbox now. I’ve been developing the OS and the players and a total redesign of the PCB, 4 layer board, with the two power plates inside the board, giving it a nice capacitor feel so everything got a nice gulp of power where it needed, and shielding. all the signals on the top and bottom layers for ram and display and virtually ZERO noise! there was some from the display but that was gone when I tethered a ground wire from the displays shield plate! now, there is no sound at all! Well not that I can tell. even with the Scopes!

sidbox4.jpg

This is what the sidbox is today.

We have begun a nice facebook group and is gaining interest everyday!

Soon we’ll be able to start the kickstarter!

With everyone backing and supporting this project, we’ll go far!!!