pepperheart

Should someone still be interested in how to get the uart2 interface running with an RS485 on a rockpi 4b (plus in my case), I was able to do so by making sure the serial port is active (which it should be by default) by following this post: Decompile the necessery dtb file, make sure serial@ff1a0000 status is "okay" and recompile it again. Deactivate console in the /boot/armbianEnv.txt and /boot/boot.cmd by setting it to "none" and recompile boot.cmd as show in this article: https://docs.armbian.com/User-Guide_Fine-Tuning/#how-to-toggle-boot-output And now final part, which took me a whole day to figure out, because deactivating the console wasn't enough since you need also to deactivate the getty service which occupies the ttys2 for the boot console. Simply move it as root out of the systemd directory, reload systemd daemon and restart your device: mv /etc/systemd/system/getty.target.wants/serial-getty@ttyS2.service ~ && systemctl daemon-reload && shutdown -r now Some of the above mentioned steps may be unnecessery, but the result is more important for me at this point