3.4.12.1 Serial Debug (DBGU) Port

The SAM9X75 Curiosity Pro board features a dedicated serial port for debugging, accessible through the FTDI header (J63). Various interfaces can be used as a USB/Serial DBGU port bridge, such as the FTDI TTL-232R USB-to-TTL serial cable.

Figure 3-38. Serial Debug Port

The DBGU serial port uses the MCP1700/3.3V LDO to prevent any voltage higher than 3.3V from being applied to any 3.3V-only tolerant external USB-to-UART converter. For more details about the MCP1700/3.3V device, refer to the product web page.

An inexpensive level shifter solution is also implemented using two TN2106 N-channel MOSFETs. For more details about the TN2106 device, refer to the product web page.

Table 3-19. Serial Debug Port Signal Description
PIOSignal NameSignal Description
PA26DBGU0_0.DBGU_RXUART receive data line
PA27DBGU0_0.DBGU_TXUART transmit data line