The mEDBG provides a CDC COM port connection when connected to a USB host device.
The mEDBG (ATmega32U4) USART is used for communication with the CDC COM port. The USART TX/RX signals are available on the J104 header and are also connected to the ATmega328P via 0Ω resistors enabling easy disconnect from the ATmega328P if needed. The RX/TX silkscreen notation next to J104 refers to the RX and TX pins of the mEDBG (ATmega32U4).
| J104 Pin | ATmega32U4 | ATmega328P | Function |
|---|---|---|---|
| 1 - USART TxD | PD3 | PD0 (RxD) | TxD out from ATmega32U4 |
| 2 - USART RxD | PD2 | PD1 (TxD) | RxD in to ATmega32U4 |