View source for Rockpi4/dev/use-uart2-as-application-uart

{{rockpi4_header}}

{{Languages|Rockpi4/dev/use-uart2-as-application-uart }}

    [[rockpi4 | ROCK Pi 4]] > [[rockpi4/dev | Development]] > [[Rockpi4/dev/use-uart2-as-application-uart | Use UART2 as Application UART]]

=OUTDATED=

The content below is out of date. User should use [https://docs.radxa.com/en/radxa-os/rsetup/devicetree rsetup] to enable UART overlay instead.

The original content is kept for historical purpose.

===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