Rockpi4/dev/common-interface-with-kernel-5.10
ROCK Pi 4 > Development > Common interface with Kernel 5.10
Description
If you want to use i2c, spi, uart, pwm, etc, with Kernel 5.10 in ROCK Pi 4. You'd better follow these steps.
Install essential package
Install package rockpi4-dtbo
$ sudo apt-get install -y rockpi4-dtbo
Modify file /boot/hw_intfc.conf. Add "#" to line "intfc:dtoverlay=console-on-ttyS2" and "intfc:dtoverlay=console-on-ttyS4".
#intfc:dtoverlay=console-on-ttyS2 #intfc:dtoverlay=console-on-ttyS4
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" and "intfc:dtoverlay=console-on-ttyS4".
#intfc:dtoverlay=console-on-ttyS2 #intfc:dtoverlay=console-on-ttyS4
but 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
Please note that when ROCK Pi 4 uart2 is connected with your devices like Raspberry Pi CAN/RS485 hat sending some data to uart2 on ROCK Pi 4. Please do the following step.
Check the file /boot/extlinux/extlinux.conf. And delete the following line.
menu title select kernel