Rockpi4/dev/use-uart2-as-application-uart

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    ROCK Pi 4 >  Development >  Use UART2 as Application UART

Description

If you want to use uart with Kernel > 5.10 in ROCK Pi 4. You can follow these steps.

Install essential package

 sudo apt-get install -y rockpi4-dtbo

UART

Modify file /boot/hw_intfc.conf. Set "on" to enable the optional hardware interfaces while set "off" to disable.

 intfc:uart2=on
 intfc:uart4=on

And add "#" to line "intfc:dtoverlay=console-on-ttyS2"

 #intfc:dtoverlay=console-on-ttyS2
 #intfc:dtoverlay=console-on-ttyS4

by now, the uart2 can still be used as a debug port with system log. If you don't want to output kernel messages, you can disable it as follow.

Modify file /boot/extlinux/extlinux.conf.

 append earlyprintk console=ttyFIQ0,1500000n8 rw init=/sbin/init rootfstype=ext4 rootwait  root=UUID=8650cdca-49b0-4431-9667-5c639f6bab89 console=ttyS2,1500000n8

Delete strings console=ttyFIQ0,1500000n8 and console=ttyS2,1500000n8 in this line.

 append earlyprintk rw init=/sbin/init rootfstype=ext4 rootwait  root=UUID=8650cdca-49b0-4431-9667-5c639f6bab89