An ATmega4809 "Breadboard Arduino"

Unlike the classic Arduino Uno with its ATmega328P microcontoller, the newer Arduino Nano Every and Arduino Uno WiFi Rev2 are based on the ATmega4809 from Microchip's megaAVR 0-series.

Aside from more program memory and RAM than the ATmega328P, the ATmega4809 has some interesting features, including a faster 20 MHz clock, configurable logic, and an event system. It's also the only member of its family available in a breadboardable DIP package for easy prototyping. Naturally, Technoblogy’s David Johnson-Davies went to work turning the chip into a DIY next-gen “Arduino,” complete with a USB interface.

His design takes two forms, the slightly simpler of which mounts an FTDI USB-to-serial board on the the breadboard for communication. The other option uses an MCP2221A USB-to-serial converter on the board itself, which involves soldering a USB connector up to a four-pin header for data transfer. This version has a reset button as well, needed to set the chip up to program as it lacks the proper handshaking signal.

To get it functioning, Johnson-Davies also had to install a bootloader on the ATmega4809. The one provided by Arduino doesn’t work here, but he was instead able to implement a core for the megaAVR 0-series written by Hans Eirik Bull. Once done, the MCU/breadboard can be programmed like a normal Arduino in the IDE, or you can even get feedback over the serial monitor for troubleshooting. Perhaps you could install Johnson-Davies’ uLisp interpreter that we featured here, running on an ATtiny3216.