Hi.

I'm trying to connect my orange pi to pc using UART3 but it doesn't work.
I connected UART3 to my pc using USB to serial converter and my pc recognized it.

 

so I open a serial session in putty.

 

then  when I tried to connect in orange pi it doesn't work.
I tried command

minicom -b 9600 -D /dev/ttyS3

but it doesn't work.
system properties:
 

Linux orangepipcplus 4.19.62-sunxi #5.92 SMP Wed Jul 31 22:07:23 CEST 2019 armv7l GNU/Linux

dmesg | grep tty output:

[    0.000000] Kernel command line: root=/dev/mmcblk0p1 rootwait rootfstype=ext4 console=ttyS0,115200 console=tty1 hdmi.audio=EDID:0 disp.screen0_output_mode=1920x1080p60 panic=10 consoleblank=0 loglevel=1 ubootpart=a7e8d17a-01 ubootsource=mmc usb-storage.quirks=0x2537:0x1066:u,0x2537:0x1068:u   sunxi_ve_mem_reserve=0 sunxi_g2d_mem_reserve=0 sunxi_fb_mem_reserve=16 cgroup_enable=memory swapaccount=1
[    0.000186] console [tty1] enabled
[    1.903679] console [ttyS0] disabled
[    1.923829] 1c28000.serial: ttyS0 at MMIO 0x1c28000 (irq = 44, base_baud = 1500000) is a U6_16550A
[    1.923882] console [ttyS0] enabled
[    1.946824] 1c28400.serial: ttyS1 at MMIO 0x1c28400 (irq = 45, base_baud = 1500000) is a U6_16550A
[    1.969687] 1c28800.serial: ttyS2 at MMIO 0x1c28800 (irq = 46, base_baud = 1500000) is a U6_16550A
[    1.990464] 1c28c00.serial: ttyS3 at MMIO 0x1c28c00 (irq = 47, base_baud = 1500000) is a U6_16550A

and output of 

cat /proc/device-tree/soc/serial@1c28c00/status

is okay.

and armbianEnv.txt contains:

verbosity=1
console=both
overlay_prefix=sun8i-h3
overlays=i2c0 uart1 uart2 uart3 usbhost0 usbhost1 usbhost2 usbhost3
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u

Thanks for your help.

Try 115200 BPS instead of 9600

3 minutes ago, lanefu said:

Try 115200 BPS instead of 9600

Still not working ...

Just confirming--- you're using a USB TTL serial adapter right. not USB-RS232?

12 minutes ago, lanefu said:

Just confirming--- you're using a USB TTL serial adapter right. not USB-RS232?

I'm trying with both.
but can you explain their difference?

6 minutes ago, mohjam77 said:

I'm trying with both.
but can you explain their difference?

 

Signaling voltage... TTL serial is 3.3V - 5V signalling.. RS232 is 12v. 

 

You'll definitely want to use the USB TTL serial on your PC.