NanoPi Neo serial port

Troubleshooting
1

Hi
I try open serial port /dev/ttyS1 and /dev/ttyS2
When I read and write have errno: Input/output error

proc/tty/driver
serinfo:1.0 driver revision:
0: uart:U6_16550A mmio:0x01C28000 irq:40 tx:11791 rx:0 RTS|DTR
1: uart:unknown port:00000000 irq:0
2: uart:unknown port:00000000 irq:0
3: uart:unknown port:00000000 irq:0
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


/dev/ttyS2 and /dev/ttyS2 is 0666
this serials are disable in kernel?

Smashing

2

The Armbian-based images with Linux 5.x kernel have device tree overlays available to enable additional serial/UART devices:

sed -Ei 's/^(overlays=.*)/\1 uart1/' /boot/armbianEnv.txt
reboot

Respectively manually add uart1, uart2 or uart3 to the overlay= line in /boot/armbianEnv.txt.

A full list of available overlays can be found in /boot/dtb/overlay/, the ones with the sun8i-h3- prefix (as defined in /boot/armbianEnv.txt). Those can be added by skipping sun8i-h3- and .dtbo from the file name, hence without prefix and file extension.

3

hi, i came to this post since i´m trying to enable uart on a nano pi neo 3…
in /boot/armbianEnv.txt i haven’t “overlays”
simply ovarlay_prefix = rockchip

and in the /boot folder a link to: rockchip and inside there is a folder called overlay… how i can enable a uart port?
please help me!

4

On NanoPi NEO3 the serial device ttyS2 should be enabled by default. Not sure what about ttyS0 and ttyS1, can you try to change the line

extraargs="net.ifnames=0"

to

extraargs=net.ifnames=0 console=ttyS0,115200

or

extraargs=net.ifnames=0 console=ttyS1,115200

(the quotation is not required)

There is an overlay to enable UART4, which is likely ttyS3. To enable it, add the overlays line yourself:

overlays=uart4

Boot output can then be enabled the same way as above. To enable a login console on a UART, e.g. for ttyS0:

systemctl enable serial-getty@ttyS0

while this may not be required when it is enabled for boot output (extraargs) and a serial console connected. systemd has an auto-generator to enable a login prompt then.