I started yesterday evening to make a…sound board, sort of. A simple sound data buffer in the FPGA (two sprites were lost in action…) and being able to write to the buffer using the SPI interface. Then, if there are any data in the buffer, the FPGA reads the data and outputs it using 8-bit PWM on the very last free pin. I didn’t have much hope about the sound quality, but it turned out to be quite OK using only a simple RC filter directly on the output of the FPGA. The PCB I’m waiting for has a nice, sharp butterworth filter and a local digital buffer, so it should be even better.
The sound is loaded into RAM on the Pi. Seems it happily allocates at least 40M of RAM. 🙂
Seems YouTube even recognized the music and added some ads to punish me. 😉
Arcade monitor, oscilloscope showing the audio output and computer screen showing writes to the FPGA.