I was unable to get UART working on my Orange Pi Zero. Note, that I am not trying to use UART to access the terminal, I need to use the UART port to say connect to an arduino, etc. 

 

 Here is the output of some commands that I thought may be helpful. 

uname -a
Linux orangepizero 4.10.0-sun8i #14 SMP Fri Feb 24 03:02:58 CET 2017 armv7l armv7l armv7l GNU/Linux

dmesg | grep TTY

[    0.000000] Kernel command line: root=UUID=b5fc390b-23ef-47a8-83fb-0fd94a3d2dcc rootwait rootfstype=ext4 console=tty1 console=ttyS0,115200 cgroup_enable=memory swapaccount=1 hdmi.audio=EDID:0 disp.screen0_output_mode=1920x1080p60 panic=10 consoleblank=0 enforcing=0 loglevel=1 ubootpart=8b708352-01 ubootsource=mmc   sunxi_ve_mem_reserve=0 sunxi_g2d_mem_reserve=0 sunxi_fb_mem_reserve=16
[    0.001005] console [tty1] enabled
[    4.126456] console [ttyS0] disabled
[    4.146689] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 37, base_baud = 1500000) is a U6_16550A
[    4.146761] console [ttyS0] enabled
 

Here's how I tested communication with UART. I wired up the pins (RX <--> TX) as per the pinout at http://linux-sunxi.org/Xunlong_Orange_Pi_Zero#Locating_the_UARTI would then do, 

screen /dev/ttyS[12] 57600
[screen is terminating]

Any help is appreciated. Thanks!

 

Any help is appreciated. Thanks!

Additional serial ports are disabled by default, you need to activate them by either patching the Device Tree or using Device Tree overlays.

add "overlays=sun8i-h3-uart1" in your /boot/armbianEnv.txt and reboot.

add "overlays=sun8i-h3-uart1" in your /boot/armbianEnv.txt and reboot.

Please, this feature is not yet announced. I don't want to go through the whole forum to delete or edit overlay names in case anything changes here, we already have too much outdated info on WIP stuff.