"It's a work in progress"
2018 This project started out using an ATMEGA328P and Arduino, but I found that it was hard to write fast enough code to play songs at full speed. I then found the STM32 series of microcontrollers; It was promising, but I really didn't like the SDK or the HAL that was provided for these parts. After a few years, the Raspberry Pi Foundation released the Raspberry Pi Pico. I bought the board during its pre-order stage simply because it's a $5 microcontroller. This new board, with their own RP2040 chip, has one key feature that I didn't know at the time will make this project viable for me. The Programmable I/O (PIO).
2022 I finally got to looking at the datasheet for this board during DEFCON 2022, where they used the RP2040 for their interactive badge. The PIO section caught my eye, but I didn't look into it until a month later.
When I read the examples they had for driving WS2812 LED strips, I realized what I could do with this extra power. I could easily get data to the chip on time, every time; and have plenty of time for drawing a UI to a screen, fetching data from an SD card over SPI, and in the future, emulating other sound chips for game systems with AD/PCM and other chips.
I made this development board for the project.
GPIO 0-7 are connected to D0-D7 on the YM2151. GPIO 8-10 are connected to the
A0, WR, and CS pins. I'm using SPI to connect to the SD card, and an
LTC6903 programmable clock generator making the main clock for the YM2151.
The supporting circuitry for the YM2151 was ripped from the same place I got the chip from, a Yamaha CX5 Music Computer.
To be documented... and written
Special thanks to:
- ReimuNotMoe for their work on
TinyVGM. This framework for digesting
the
.vgmfiles is really helpful for me. - Aidan Lawrence for open-sourcing his YM2151 music player which got me started in the ATMEGA328P days.