December 24, 2021

Orange Pi 4 (Rockchip 3399) Serial console

Perhaps some people get one of these, hook up an HDMI monitor and a USB keyboard (and mouse) and put Debian on an SD card. Then away they go.

This is not what I want to do. For one thing I don't have an HDMI monitor (other than the big one connected to my desktop system). And I am not interested in running linux. I want to do low level development, and for that sort of thing, a serial console is the only game in town.

The serial port runs at 1500000 baud, which is a crazy high baud rate. My CP2102 usb to serial gadget did not support this speed, but I have a bunch of CP2104 usb to serial gagets, and they work fine. I connect 3 wires, ground, RxD and TxD.

The 3 pin serial console header on the board has signals in this order: Ground, Rx, Tx - with ground closest to the corner of the board. I connect Tx on my serial dongle to Rx on the board, and Rx on my serial dongle to Tx on the board.

Then I use picocom, with an invocation like this:

picocom -b 1500000 /dev/ttyUSB0
I actually have a short script that scans the /dev directory for ttyUSB and TTYACM devices and tries to make an intelligent selection. I usually does the right thing.

Have any comments? Questions? Drop me a line!

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