NanoPi Neo Air-LTS - UART1 ttyS1 not working

[stefan.timm@eveko.de]

Good Afternoon, I have a problem to set up the UART1 ttyS1 on NanoPi NEO Air-LTS
I want to use the tiny Air Module with two serial ports for an Dual (W)M-Bus Module from Solvimus.

How is the correct layout for the PINs and the way to config the Overlay and somthing else to get it work?
I try since days to config and do a loop-test on UART1 ttyS1 and it‘s not working

I do a loopback an the serial port UART1 ttyS1 and UART2 ttyS2, UART2 ttyS2 is working, UART1 ttyS1 is not working. We think there is another service bind to the UART1 ttyS1.

Please find down all information about the config:

Welcome to Ubuntu 16.04.7 LTS 4.14.111
System load: 0.04 Up time: 22 min Local users: 2
Memory usage: 12 % of 491Mb IP: 192.168.160.150
CPU temp: 31°C
Usage of /: 73% of 6.1G

root@NanoPi-NEO-Air:~# sudo stty -F /dev/ttyS1 -a
speed 9600 baud; rows 0; columns 0; line = 0;
intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof = <undef>; eol = <undef>; eol2 = <undef>; swtch = <undef>;
start = <undef>; stop = <undef>; susp = <undef>; rprnt = <undef>; werase = <undef>; lnext = <undef>; discard = <undef>;
min = 0; time = 0;
-parenb -parodd -cmspar cs8 -hupcl -cstopb cread clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff -iuclc -ixany -imaxbel -iutf8
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt -echoctl -echoke -flusho -extproc

root@NanoPi-NEO-Air:~# cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:U6_16550A mmio:0x01C28000 irq:44 tx:11093 rx:0 RTS|DTR
1: uart:U6_16550A mmio:0x01C28400 irq:45 tx:46 rx:0 RTS|CTS|DTR
2: uart:U6_16550A mmio:0x01C28800 irq:46 tx:40 rx:0 CTS
3: uart:U6_16550A mmio:0x01C28C00 irq:47 tx:35934 rx:2669 RTS|CTS|DTR
4: uart:unknown port:00000000 irq:0
5: uart:unknown port:00000000 irq:0
6: uart:unknown port:00000000 irq:0
7: uart:unknown port:00000000 irq:0

dmesg | grep tty
[ 0.000000] Kernel command line: console=ttyS0,115200 earlyprintk root=/dev/mmcblk0p2 rootfstype=ext4 rw rootwait fsck.repair=yes panic=10 fbcon=map:0 data=/dev/mmcblk0p3 snd-soc-core.pmdown_time=3600000
[ 0.610745] console [ttyS0] disabled
[ 0.630936] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 44, base_baud = 1500000) is a U6_16550A
[ 1.405085] console [ttyS0] enabled
[ 1.431339] 1c28400.serial: ttyS1 at MMIO 0x1c28400 (irq = 45, base_baud = 1500000) is a U6_16550A
[ 1.462946] 1c28800.serial: ttyS2 at MMIO 0x1c28800 (irq = 46, base_baud = 1500000) is a U6_16550A
[ 1.492523] 1c28c00.serial: ttyS3 at MMIO 0x1c28c00 (irq = 47, base_baud = 1500000) is a U6_16550A

uEnv.txt
#################################################################
# General options
#################################################################
ramdisk=rootfs.cpio.gz
kernel=zImage
fix_addr 0x44500000
kernel_addr=0x46000000
ramdisk_addr=0x47000000
dtb_addr=0x48000000

debug_port=ttyS0,115200
fsck.repair=yes

# 0 = /dev/fb0, First framebuffer
# 1 = /dev/fb1, Second framebuffer
# README: linux/Documentation/fb/fbcon.txt
fbcon=map:0





#################################################################
# Overlay options
# README: /overlays/README.txt
#################################################################

#uart0/enable=no
uart1/enable=yes
#uart2/enable=no
#uart3/enable=no

#i2c0/enable=no
#i2c1/enable=no
#i2c2/enable=no

#spi0/enable=no

#pwm0/enable=no

#ir/enable=no

#tft28/enable=no
#tft28/speed=50000000
#tft28/rotate=90
#tft28/fps=33
#tft28/debug=0x0

#tft13/enable=no
#tft13/speed=50000000
#tft13/rotate=0
#tft13/fps=0x0
#tft13/debug=0x0

[Pravall]

It looks like UART1 (ttyS1) might be in use by another service or not properly configured. First, check if any process is using it and stop any conflicting services. System logs may provide clues if there’s an error or hardware issue. Also, ensure the correct pins are connected for TX and RX. If the issue persists, try modifying the overlay settings in your configuration file and restart the system.