Have you already ordered our open source mechanical keypad ANAVI Macro Pad 8 from the recent crowdfunding campaign? It is powered by Microchip ATmega32U4: an 8-bit microcontroller with 32K bytes of ISP Flash, USB Controller and I2C. This microcontroller is part of the AVR family of microcontrollers developed since 1996 by Atmel and acquired by Microchip Technology in 2016.
Microchip ATmega32U4 is how ANAVI Macro Pad 8 connects to the USB port of a personal computer, shows graphics and text on the mini OLED display through I2C. Furthermore, this microcontroller has more than enough general-purpose input/output (GPIO) pins for the mechanical switches.
The popular open source Quantum Mechanical Keyboard (QMK) Firmware supports Microchip ATmega32U4 and therefore it is easy to use as the default firmware for ANAVI Macro Pad 8. However, it is technically also possible use ANAVI Macro Pad 8 as a development board and upload Arduino sketches compatible with Arduino Leonardo through Arduino IDE or PlatformIO. Many popular development boards such as Arduino Leonardo, SparkFun Pro Micro, Teensy 2.0, Olimex eduArdu also use ATmega32U4.