Mackie MCU Pro Expandable USB/MIDI Control Surface MCU PRO B&H
Connecting USB to Simple MCUs - Circuit Cellar
Amazon.com: Aihjcnele Attiny85 Digispark Kickstarter USB Module Development Board Compatible IDE for Arduino General Micro USB MCU Development Module Compatible with UNO R3 PWM I2C SPI ADC I/O with Cable Wire :