redrathnure
commented
4 months ago Most likely the /dev/ttyS2 is an UART2 port, which is connected to CH340C IC (USB Type C debug port). And most likely it's configured somehow via console/consoleargs boot arguments. UnfortunatelyI am not sure how to change it in Armbian. Perhaps something should be added into /boot/armbianEnv.txt files, and probably you should check official Armbian forum for instructions how to do this in right way.
BTW I found a file with following content:
if test "${console}" = "display" || test "${console}" = "both"; then setenv consoleargs "console=tty1"; fi
if test "${console}" = "serial" || test "${console}" = "both"; then setenv consoleargs "console=ttyS2,1500000 ${consoleargs}"; fiPerhaps you may avoid second line condition explicitly declaring setenv console "display"...
frap129
Phil1988
What happened?
I cant get my serial port ttyS2 to work as I want to. I am using this OS: Armbian-unofficial_24.2.0-trunk_Mkspi_bookworm_edge_6.6.7.img.xz
Its seems that even if all services being shut down/disabled/stopped, there is something using it.
How do I know? My oscilloscope shows something.
TL;DR - nothing is actively running on the ttyS2
No process is using the ttyS2: ``` mks@mkspi:~/X3seriesLCD$ sudo lsof | grep ttyS* systemd-l 694 root 7r REG 0,24 4096 5312 /sys/devices/virtual/tty/tty0/active systemd-l 694 root 17u CHR 4,6 0t0 29 /dev/tty6 python 904 mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 python 904 1116 python mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 1116 python mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 python 904 1587 python mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 1587 python mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 python 904 1588 python mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 1588 python mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 python 904 1617 python mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 1617 python mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 python 904 1618 python mks 11uW CHR 4,64 0t0 134 /dev/ttyS0 python 904 1618 python mks 18uW CHR 166,0 0t0 690 /dev/ttyACM0 Xorg 952 root 12u CHR 4,2 0t0 25 /dev/tty2 Xorg 952 1229 InputThre root 12u CHR 4,2 0t0 25 /dev/tty2 agetty 1028 root cwd DIR 179,2 4096 2 / agetty 1028 root rtd DIR 179,2 4096 2 / agetty 1028 root txt REG 179,2 134480 35604 /usr/sbin/agetty agetty 1028 root mem REG 179,2 3407104 9498 /usr/lib/locale/locale-archive agetty 1028 root mem REG 179,2 353616 3899 /usr/lib/locale/C.utf8/LC_CTYPE agetty 1028 root mem REG 179,2 1651472 31068 /usr/lib/aarch64-linux-gnu/libc.so.6 agetty 1028 root mem REG 179,2 202912 30789 /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1 agetty 1028 root mem REG 179,2 27028 59819 /usr/lib/aarch64-linux-gnu/gconv/gconv-modules.cache agetty 1028 root 0u CHR 4,1 0t0 24 /dev/tty1 agetty 1028 root 1u CHR 4,1 0t0 24 /dev/tty1 agetty 1028 root 2u CHR 4,1 0t0 24 /dev/tty1 agetty 1028 root 4r a_inode 0,15 0 2074 inotify sudo 5264 root 8u CHR 5,0 0t0 15 /dev/tty sudo 5266 root 8u CHR 5,0 0t0 15 /dev/tty ``` no systemd-services running; ``` mks@mkspi:~/X3seriesLCD$ systemctl list-units | grep serial sys-devices-platform-ff110000.serial-tty-ttyS0.device loaded active plugged /sys/devices/platform/ff110000.serial/tty/ttyS0 sys-devices-platform-ff120000.serial-tty-ttyS1.device loaded active plugged /sys/devices/platform/ff120000.serial/tty/ttyS1 sys-devices-platform-ff130000.serial-tty-ttyS2.device loaded active plugged /sys/devices/platform/ff130000.serial/tty/ttyS2 sys-devices-platform-serial8250-tty-ttyS3.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS3 sys-devices-platform-serial8250-tty-ttyS4.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS4 sys-devices-platform-serial8250-tty-ttyS5.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS5 sys-devices-platform-serial8250-tty-ttyS6.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS6 sys-devices-platform-serial8250-tty-ttyS7.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS7 system-serial\x2dgetty.slice loaded active active Slice /system/serial-getty ```Permissions look good:
But the kernel messages seems to be configured to use ttyS2 as console:
How can I shut ther kernel down so its not using
console=ttyS2,1500000? I simply want to use this serial port for serial communication :)Not related: And it would be great of you can change the links from: https://openqidi.com/books/build-entire-operating-system-and-klipper-from-scratch/page/freeqidi to https://github.com/Phil1988/FreeQIDI
See here: https://github.com/redrathnure/armbian-mkspi/releases
and there https://github.com/redrathnure/armbian-mkspi
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