As shown in the schematic, ... To program the STM8, you can use either the SWIM interface, or disconnect the ESP8266’s power pin, switch up the TX and RX wires, ...

We’ve seen a lot of ESP8266 projects in the past, but this one most definitely qualifies as a hack. [Cnlohr] noticed that the ESP8266, when overclocked, could operate the I2S port at around 8… ...