UART

The Rhino Pi IQ9N provides 4 serial ports: CPU-DBG, CPU-UART, RTSS-DBG, and RTSS-UART, all using the WAFER-GH1.25-4PLB connector.

Interface Description

For the positions of CPU-DBG, CPU-UART, RTSS-DBG, and RTSS-UART on the board, see the interface layout diagram in Rhino Pi IQ9N Interface Description on the first page.

Interface	Type	Purpose
CPU-DBG	Debug serial port	View CPU-side boot logs and enter the debug terminal
CPU-UART	Functional serial port	CPU-side service data transmission and reception
RTSS-DBG	Debug serial port	View RTSS-side boot logs
RTSS-UART	Functional serial port	RTSS-side service data transmission and reception

Pin Definitions

Pin	Signal	Description
1	VCC_3VS	3.3V
2	UART_TX	Transmit
3	UART_RX	Receive
4	GND	Ground

When wiring, note the crossover connection: the device TX goes to the peer RX, and the device RX goes to the peer TX.

Testing Notes

[To be added: serial transmit/receive test method — hardware testing of this group of serial ports has not been completed and verified yet; the device node, parameter configuration, and example code will be added once testing confirms it is usable.]

Viewing Debug Logs

Connect a USB-to-serial adapter to CPU-DBG, then use a serial terminal tool on the PC to view the boot logs:

# Example under Linux
sudo screen /dev/ttyUSB0 115200

Notes

• The interface is 3.3V level; do not connect RS232/RS485 level signals directly.
• Accessing the serial port requires the appropriate permissions; you can add the user to the dialout group:

sudo usermod -aG dialout aidlux

• After changing the baud rate or other parameters, log in again for the permissions to take effect.
• For wiring and interface position descriptions, see Debug & Expansion Interfaces.