Pro Micro Microcontroller ATmega32U4 5V 16MHz
If you plan to hotswap the controller you’ll need: Mill Max Socket Pins + Low Profile Controller Sockets.
This microcontroller development board has 4 channel 10 bit ADC, 5 PWM pins, 12 DIO, and a hardware serial connection Rx and Tx you are familiar with. Running on 16MHz and 5V, this board will remind you a lot of other Arduino compatible boards that you like. There is a voltage regulator on board, so it can accept up to 12V DC.
Four 10-bit ADC pin and 12 digital I / O (5 PWM capability). Dimensions: 1.3×0.7″