Good grief, can't believe it's been almost a year since I posted about this! ![:shock:]( "Shocked")
To give a brief status update, the project is progressing slowly and has morphed into a sound cartridge with some extra bits. The current hardware is not representative of the final design, it's more of a platform for developing the required FPGA code, but it works and is stable.
At the moment, features implemented in the FPGA are:
- 2 x SN76489 sound generators (first one is compatible with the old Project Expansions sound cart)
- 512KB of on-board RAM accessible via some registers in &FC page
- an 8-bit sample channel capable of DMA playback from the on-cart RAM, currently fixed at 8KHz sample rate
- two programmable counters
- 2K of FRAM for storing settings
This completely maxes out the small FPGA I'm using, so now it's decision time. Do I redesign around a larger FPGA and add more features, or just freeze the project as is?
Part of me wants to push forward and enhance the audio capabilities even further, more sample channels and possibly a Yamaha OPL or OPN compatible FM syth. And flash memory is very cheap now, so a large on-board wavetable sample set isn't out of the question either.
But I'm aware that's very out of keeping with an 80s 8-bit micro like the Electron, there's a temptation to split the design into two cartridges. A basic one with the RAM and SN76489s for games and another version with sample channels, FM synths, MIDI, etc, for audio nerds like me![:D]( "Very Happy")
To give a brief status update, the project is progressing slowly and has morphed into a sound cartridge with some extra bits. The current hardware is not representative of the final design, it's more of a platform for developing the required FPGA code, but it works and is stable.
At the moment, features implemented in the FPGA are:
- 2 x SN76489 sound generators (first one is compatible with the old Project Expansions sound cart)
- 512KB of on-board RAM accessible via some registers in &FC page
- an 8-bit sample channel capable of DMA playback from the on-cart RAM, currently fixed at 8KHz sample rate
- two programmable counters
- 2K of FRAM for storing settings
This completely maxes out the small FPGA I'm using, so now it's decision time. Do I redesign around a larger FPGA and add more features, or just freeze the project as is?
Part of me wants to push forward and enhance the audio capabilities even further, more sample channels and possibly a Yamaha OPL or OPN compatible FM syth. And flash memory is very cheap now, so a large on-board wavetable sample set isn't out of the question either.
But I'm aware that's very out of keeping with an 80s 8-bit micro like the Electron, there's a temptation to split the design into two cartridges. A basic one with the RAM and SN76489s for games and another version with sample channels, FM synths, MIDI, etc, for audio nerds like me
Statistics: Posted by Ramtop — Mon May 12, 2025 1:20 am