OPL3 VGM player powered by STM32
This project is a hardware video game music (VGM) player that uses a genuine YMF262 (OPL3) sound chip and its accompanying YAC512 DAC. There is no emulation here. This is the real chip.
Included in this repository is the complete schematic, firmware source, and KiCAD board files. Feel free to make your own board, but please don't resell them :)
If you would like to purchase an official complete Throwback Operator board, you can order one from me here: https://www.aidanlawrence.com/product/throwback-operator/
The YMF262, also known as the Operator Type L3 (OPL3), is an 18-channel FM sound chip that was commonly found inside of personal computers in the mid to late 1990's. Most notably, the OPL3 was found on the Sound Blaster Pro 2 and the Sound Blaster 16. The OPL3 is backwards compatible with the OPL2 (YM3812). The OPL2 is backwards compatible with the original OPL (YM3526). This means that the Throwback Operator is capable of playing back OPL3, OPL2, and OPL tracks. The OPL2 was found on the original Adlib and Sound Blaster cards. The OPL was usually found within arcade machines.
The clock signal for the YMF262 is dynamically generated from the microcontroller. The timers on this particular board only have 16-bit resolution, so VGMs with exotic frequencies may not sound perfectly in tune. Standard clock OPL2 and OPL3 VGMs will often sound just fine though.
VGM stands for Video Game Music, and it is a 44.1KHz logging format that stores real sound chip register information. My player will parse these files and send the data to the appropriate chips. You can learn more about the VGM file format here: http://www.smspower.org/Music/VGMFileFormat
http://www.smspower.org/uploads/Music/vgmspec170.txt?sid=58da937e68300c059412b536d4db2ca0
The Throwback Operator accepts MicroSD cards formatted as FAT32. Your SD card must only contain uncompressed .vgm files. VGZ FILES WILL NOT WORK! You may download .vgz files and use 7zip to extract the uncompressed file out of them. Vgm files on the SD card do not need to have the .vgm extension. As long as they contain valid, uncompressed vgm data, they will be read by the program regardless of their name. You can find VGM files by Googling "myGameName VGM," or by checking out sites like http://vgmrips.net/packs/
You can use a serial connection to control playback features. The commands are as follows:
| Command | Result |
|---|---|
| + | Next Track |
| - | Previous Track |
| * | Random Track |
| / | Toggle Shuffle Mode |
| . | Toggle Song Looping |
| r: | Request song |
| ? | What song is playing? |
| ! | Toggle the OLED display |
A song request is formatted as follows: r:mySongFile.vgm
Once a song request is sent through the serial console, an attempt will be made to open that song file. The file must exist on the SD card, and spelling/capitalization must be correct.
Need an easy-to-use serial console? I've made one here.
The on-board microcontroller is a STM32F103C8T6, the same microcontroller found on the popular "blue pill" development boards. Therefore, programming the Throwback Operator boards is fairly similar. The firmware was built with Visual Studio Code with the PlatformIO extension installed.
Programming over Serial:
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Connect your Throwback Operator board to your computers USB port.
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Ensure that you have the CH340 driver installed. Windows 10 should have this automatically, otherwise, grab the driver here
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Ensure nothing else is currently connected to your board over serial.
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On the top of the board, you will see two black jumpers. By default, these jumpers are both in the "Down" position (middle pin and bottom pin jumped).
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Remove the left jumper and reattach it to the "Up" position (middle pin and top pin jumped).
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Press the RESET button on the Throwback Operator board
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You can either program the device with the flashing tool linked below, or from the source code.
DOWNLOAD THE FLASHING TOOL HERE
- Windows users are reccomended to run the pre-compiled "Flash.exe" file. All other operating system users must run the Flash.py file. Dependancies and instructions are listed in the Readme file.
- After successfully running the flashing tool, you are done and don't need to continue with the following instructions.
If you plan to build from the source code instead:
- In VS Code (or whatever your IDE of choice is), navigate to the
platformio.iniand ensure the upload protocol is set toserial - Hit the upload button (Arrow icon in the bottom bar of VS code)
- Once your code is uploaded, replace the left jumper to its original "Down" position
Occasionally, when the player is first plugged in, it will hang or get caught in a boot-loop. Plugging in a USB cable gives breif moments of unstable power when the contacts inside of the connector are jostling against eachother which may place the SD card in an unknown state. Simply disconnect and reconnect the USB cable if you are caught in a bootloop.
This player is for OPL-family VGMs only. That means you can play any VGM file that contains data for the YM3526 (OPL), YM3812 (OPL2) or the YMF262 (OPL3).
Ensure that your VGM files are uncompressed. VGZ files will not work. Simply use 7zip on VGM files to extract the VGM files within.
Make sure your SD card is formatted to FAT32 and only contains VGM files. Folders are not supported.
Voodle has contributed a 3D-printable enclosure for the Throwback Operator! https://www.thingiverse.com/thing:4577831
Thanks, Voodle!