Rock Pi 4C+ UART2 can't send data

#1

使用官方系统apt update & grade后，根据官方指导，设置了/boot/hw_intfc.conf ，具体如下：
Run the official system， apt update & grade, and then set /boot/hw_intfc.conf according to the official instructions, as follows:

>    intfc:pwm0=off
>    intfc:pwm1=off
>    intfc:uart2=on
>    intfc:uart4=on
>    intfc:spi1=off
>    intfc:spi2=off
>    intfc:i2c2=off
>    intfc:i2c6=off
>    intfc:i2c7=off
>    
>    # Devicetree Overlay Enable, uncomment to enable .dtbo under /boot/overlays/.
>    
>    #intfc:dtoverlay=at24c02
>    #intfc:dtoverlay=two-color-led
>    #intfc:dtoverlay=console-on-ttyS2
>    #intfc:dtoverlay=console-on-ttyS4
>    #intfc:dtoverlay=devspi1
>    #intfc:dtoverlay=devspi2

重启系统后，安装minicom使用ttyS2发送数据，接收端（PC）接收不到数据，rock pi可以正常接收PC发送数据。尝试更新u-boot，重启后无法启动系统。如何解决？
After reboot, install minicom and use ttyS2 to send data. The receiving device (PC) cannot receive the data, but the rock PI can normally receive the data sent by the PC. Try to update u-boo, but the system cannot run after reboot. How to fix it?

#2

难道官方也没解决？默认配置的时候 Serial Console都没有任何输出信息。我也真的是筋疲力尽了，不知道刷了多少次系统了。放弃rock pi了。

Hasn’t the official solved it? In the default configuration, the serial console does not have any output information. I’m really exhausted. I don’t know how many times I have installed the system.
I decided to give up rock PI.

#3

My test image and board:
image: rockpi-4cplus-ubuntu-focal-server-arm64-20220601-1106-gpt.img.xz
board: rockpi-4plus v1.2

rockchip-overlay and rockpi4-dtbo already installed.

Enabled the uart2 and uart4, disable the console-on-ttyS2 and console-on-ttyS4 on /boot/hw_intfc.conf as follow:

intfc:pwm0=off
intfc:pwm1=off
intfc:uart2=on
intfc:uart4=on
intfc:spi1=off
intfc:spi2=off
intfc:i2c2=off
intfc:i2c6=off
intfc:i2c7=off

# Serial console on UART2
#intfc:dtoverlay=console-on-ttyS2

# Serial console on UART4
#intfc:dtoverlay=console-on-ttyS4

Deleted the console=ttyS2,1500000n8 on /boot/extlinux/extlinux.conf as follow:

timeout 10
menu title select kernel

label kernel-4.4.194-2-rk3399-rockchip-g60f7355ddb2a
    kernel /vmlinuz-4.4.194-2-rk3399-rockchip-g60f7355ddb2a
    initrd /initrd.img-4.4.194-2-rk3399-rockchip-g60f7355ddb2a
    devicetreedir /dtbs/4.4.194-2-rk3399-rockchip-g60f7355ddb2a
    append rw init=/sbin/init rootfstype=ext4 rootwait  root=/dev/mmcblk0p5

Deleted the file /etc/default/console .

I tested the UART2(ttyS2) and UART4(ttyS4) for data transmission. UART4 is fine for Tx and Rx. But UART2 is not work on Tx. I really don’t know why, and I can’t find any solution in wiki or forums.
If any friend have any solution, please tell me, thanks very much! @jack

#4

Hi, @jackedison911

I will test and get back to you soon.

#5

Please follow this guide:

https://wiki.radxa.com/Rockpi4/dev/use-uart2-as-application-uart

#6

I’ve tried the same step for many times. Uart4 is always OK. Uart2 Rx is always OK.

My Pi4C+ has never output any debug information since I owned it. So I think maybe Uart2 Tx port was broken. But I really have no way to judge that it is broken now.

#7

Hmm… Usually UART RX is damaged because of the over income voltage, not sure why TX is not working. If you flash a normal image without any modification, do you have serial console?