Jetson Nano UART and Putty

I have connected Jetson Nano UART (Pin 8 and 10) to my serial device. I can transmit and receive data between Jetson Nano and my serial device using Putty fine (both direction). I also can set UART (ttyTHS1parameters like baud rate etc) using “Stty” command. I am also able to communicate with my serial device from Ubuntu linux shell commands like “echo and cat” by redirecting the commands to talk to “/dev/ttyTHS1”.
Having said all that, here is my issue.
When I communicate from shell commands like echo and cat, the communication works fine for a few commands and then becomes garbled or unreliable. It is always fine and working on fresh cold boot for a while (few commands). However, if I have Putty running on the machine (doing nothing but open in a console), then from a shell - all commands like “echo and cat” keep working for hours talking to my serial device (which is a satellite controller).
It seems to me that, when putty is open and active Putty DOES clear tty incoming buffers in system that are needed for UART communication frequently Or redirects the driver to some Putty self managed buffer. When I DO NOT have putty running on the system, seems my ttyTHS1 device needed memory buffers become full and communication gets messed up after a few (4-5 commands and a few hundred bytes of communication). That is my guess
I do NOT know how to clear buffers (stty does not allow buffer control - just dev parameters). I tried to write data into NULL device once a while hoping that clears system buffers but did NOT help.
Expecting experts help to enable me to talk to my device for ever from my shell scripts with out having a dummy putty running on the system (as it seems like a hack to me).
Hope I described the issue clearly. If needed, I can attach the command history if needed.
Sham Datta


I am going to move your topic to the Jetson Nano category so the Jetson support team has visibility.

Hi sham.m.datta,

Are you using the devkit or custom board for Jetson Nano?

What’s your Jetpack version in use?

Do you know what trigger it become garbled?
Is there any error in dmesg at this moment?

#1. Yes. I am using NVIDIA Jetson Nano Developer Kit
#2. My Jetpack version in use (see below):
Package: nvidia-jetpack
Version: 5.1.1-b52
Architecture: arm64
Maintainer: NVIDIA Corporation
Installed-Size: 194
Depends: nvidia-jetpack-runtime (= 5.1.1-b52), nvidia-jetpack-dev (= 5.1.1-b52)
Homepage: Jetson - Embedded AI Computing Platform | NVIDIA Developer

#3. Do you know what trigger it become garbled?
Is there any error in dmesg at this moment?

No… as far as I can tell, the shell driven echo and cat keep working for 3-4 commands. I DO NOT see any dmesg on the screen (Is there a system error log I need to check? Please advise.
Sham Datta.

Jetson Nano could not support JP5, it seems some information wrong here.
Could you help to run the following command on your board and share the result?

$cat /etc/nv_boot_control.conf

You could just run dmesg while it becomes garbled.

Thanks for your reply. I have enclosed the data you requested.

Shams_dmesg.log (123.3 KB)
nv_boot_control_output.log (204 Bytes)

TNSPEC 3448-402-0000-K.0-1-0-jetson-nano-qspi-sd-mmcblk0p1
COMPATIBLE_SPEC 3448-300-0000--1--jetson-nano-devkit-

It seems you are using the Jetson Nano devkit.

Could you also help to provide the result of the following commnad?

$cat /etc/nv_tegra_release

Your dmesg seems not complete.
Could you help to provide the serial console log from power on.
Jetson Nano & NX Style - Serial Debug Console - JetsonHacks

$cat /etc/nv_tegra_release Produces following output:

R32 (release), REVISION: 7.3, GCID: 31982016, BOARD: t210ref, EABI: aarch64, DATE: Tue Nov 22 17:30:08 UTC 2022

I will try to get the serial console log from power on (not sure why dmesg was not complete. After a bit more debug, I also see that “clear” and “reset” commands DO NOT clear the buffer either. Buffer works nicely only when putty is running in background.

There is no update from you for a period, assuming this is not an issue any more.
Hence we are closing this topic. If need further support, please open a new one.

You are using Jetpack4.6.3 (R32.7.3) for Jetson Nano.

Do you mean that you are using host PC to communicate with /dev/ttyTHS1 of the board?