U2
ATMEGA16U2-MU
IC
QFN-32 (VQFN/MLF)
USB interface MCU
About this component
Firmware on this chip makes the Mega appear as a USB serial port and links it to UART0 of the ATmega2560, including the auto-reset used for uploads. If the board still runs its sketch but is no longer seen on USB, suspect this chip, its 16 MHz clock or its firmware; the firmware can be reloaded over USB DFU or through its own ICSP pads. Arduino's documentation calls it IC4.
What it does on this board
Handles USB-to-serial to program the main MCU.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.