mEDBG COM Port Connection

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 ATmega168PB via 0Ω resistors enabling easy disconnect from the ATmega168PB if needed. The RX/TX silkscreen notation next to J104 refers to the RX and TX pins of the mEDBG (ATmega32U4).

Table 1. J104 USART Header
J104 Pin ATmega32U4 ATmega168PB Function
1 - USART TxD PD3 PD0 (RxD) TxD out from ATmega32U4
2 - USART RxD PD2 PD1 (TxD) RxD in to ATmega32U4