Rock Pi S with 3 UART (Hardware v1.1)

#1

Hello,

i have all 3 UART enabled and only UART 0 and UART 1 works. UART 2 isn’t working at all. Is there any known issue? I currently need all 3 of them.

Thanks & Regards.

1 Like
#2

Update:

both pins (rx/tx) work in GPIO mode as expected but as UART2 this pins doesn’t work.

#3

It seems the Kernel DTS is buggy. This ugly patch will fix it: https://pastebin.com/a0xw6CMX
But it will disable wireless and uart0 rts/cts functions but it works for me because i have a no wifi board.
Would be nice if you can fix it in the future.

The next problem is u-boot, it will stop the autoboot if there is any data on UART0 …

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#4

uart2 (/dev/ttyS2) is still buggy on Hardware V1.2 without BT Wifi on debian buster (2020-03-16) updated (26.05.2020) with versions
rockchip-overlay 2.6
kernel 4.4.143-47-rockchip-g495ff574976c

rk3308-uart2
this enables the kernel console on uart2, but it should not

rk3308-console-on-uart2
this enables the kernel console on uart2, but with unreadable output

#5

Hi ,I suggest that you use this image https://dl.radxa.com/rockpis/images/debian/rockpis_debian_buster_minimal_arm64_20200528_1227-gpt.img.gz.

To use 3 UARTs, you can view the " Common Hardware Interfaces" part of https://wiki.radxa.com/RockpiS/Debian.

1 Like
#6

Hi, I got the debian buster (2020-03-16) image working. I will also try the newer image, thanks.
Regarding the debian buster (2020-03-16) image:
The uart2 is configured serial-console at default in boot.cmd. To disable it, one has to unset console in uEnv.txt. Example:

In uEnv.txt
console=

This disables the serial console on uart2, which enabled by default in debian buster (2020-03-16). Interestingly choosing rk3308-console-on-uart2 with default settings gives double output of console to uart2, which results in unreadable gibberish.

The new debian image is also working, and easier to configure, thank you.

#7

Stephen, I´m trying to use usart0 with usart.c and usart_advanced.c examples in mraa library.
In the wiki I saw that I have to edit uEnv.txt to erase dev/ttyS0 in console line and I already did.
There is no problem when I run the compiler for usart.c or usart_advanced.c. When I try to execute, there is a problem with mraa_uart_init_raw() function and the program fails (Failed to initialize UART). Could you help me?
I´m sorry for asking help in every single step.
Best Regards,

Gonzalo Guerrero

P. S: I’m using latest released ubuntu and usart test using rock@rockpis:~$ sudo mraa-uart dev 0 baud 1500000 send radxa and rock@rockpis:~$ sudo mraa-uart dev 0 baud 1500000 recv 1000
radxa works fine.

#9

Thanks a lot for your answer.

I’ve enable uart1 by adding overlay in uEnv.txt. Also, Ive succesfully tested uart1 with the same commands. Ive edited uart_advanced.c replacing dev_path ="/dev/ttyS0" with dev_path ="/dev/ttyS1", then I’ve compiled the C file. When I ran the executable file, the error is the same.

Regards,

Gonzalo Guerrero

#10

Check if the UART is enabled, you can execute the command. It may show some serial setup messages.

sudo dmesg | grep serial
#11

Hi! I solved this problem.
We can enable uart function in startup settings, enable uart overlay you want to use.

I believe this works for all rock cards.

  1. Find all available uart peripherals executing this command:

    find /boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/ | grep uart

the output is similiars with this:
root@rockpis:/# find /boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/ | grep uart
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-console-on-uart0.dtbo
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-console-on-uart1.dtbo
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-console-on-uart2.dtbo
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-uart0.dtbo
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-uart1.dtbo
/boot/dtbs/4.4.143-55-rockchip-g6b7accbc999b/rockchip/overlay/rk3308-uart2.dtbo

And the available ports is:
rk3308-uart0.dtbo
rk3308-uart1.dtbo
rk3308-uart2.dtbo

if that doesn’t work, find the folder avaiable into /boot/dtbs and replace it in command directory path ( /boot/dtbs/{AVAILABLE FOLDER}/rockchip/)

  1. Now whe can edit the /boot/uEnv.txt file:

verbosity=7
fdtfile=rockchip/rk3308-rock-pi-s.dtb
console=ttyS0,1500000n8
overlays=rk3308-uart0, rk3308-uart2 <====== Your uart ports can write on this line separated by a comma
rootuuid=ee60d2e1-358c-467c-acc8-a147c5b38695
initrdsize=0x5c96f8
kernelversion=4.4.143-55-rockchip-g6b7accbc999b
initrdimg=initrd.img-4.4.143-55-rockchip-g6b7accbc999b
kernelimg=vmlinuz-4.4.143-55-rockchip-g6b7accbc999b

Save it and reboot the system.

:smile:

#12

Hi androidtester,
i am using rock 3c model and enabled uart but failed to enable. can you please help how to enable?