You wanna use the Arduino serial (UART) with a Mega 4808 board? No, problem. The Mega 4808 has three serial (UART) interfaces. Here you can read on which pins you can use the serial (UART) interface a…
For testing your code for the Mega 4808 with Arduino you need a board where every pin is accesable.
The PCB for the ESP32 frontplate is done and works. Now its time to build a enclosure for it.
For a time i build the iniversal audio amplifier with a PT2033 which can be programmed over I²C. Now its time to make a frontpanel to control this amplifier
You wanna programm the Mega 4808 or an other megaAVR 0-series microcontroler? Then you need a UPDI programmer. You can buy the Atmel ICE for ~100$ or you can make your own UPDI Programmer.