We build our own custom version of esp32-arduino, in order to get some fixes we've made but haven't yet been merged in master. These are a set of currently unformatted notes on how to build and ...

The schematic does not drive a speaker directly from SP0256 pin 24. It uses a filter/coupling network followed by an amplifier: SP0256 DIGITAL OUT -> 33k series -> 0.022 uF shunt to GND -> 33k series ...