How to connect my LiDAR(UART) with TX2

Robotics & Edge Computing Jetson Systems Jetson TX2
1

Hello all,

My LiDAR use UART to communicate, but I’m not pretty sure about how to connect the pin with TX2. Currently I use USB HUB to connect my 3 LiDARs, but when I run my program for few seconds, TX2 will stuck and reboot.

I tried to use J21 pin 8 and 10, where I saw UART on the TX2 developer kit, but when I connect it with my LiDAR, TX2 will stuck ant the NVIDIA logo screen and not boot. And I don’t know how to use other UART port like J17 seems like support UART.

Sorry for being a layman and thanks for your help!

3

Hi asyuan0506,

What’s the Jetpack version in use?

Please share the full serial console log at this moment.

You can also share the full dmesg and device tree for further check.

4

Hello,

Thanks for your response, But I’m not sure what I provided is correct or not.

Jetpack version : 4.4.1 (Since I saw my L4T version is : 32.4.4-20201016123640
Serial console log, dmesg, device tree are in the txt file.

Thanks for your help!!
Device tree.txt (4.7 KB)
dmesg_log.txt (62.7 KB)
Serial console log.txt (21.6 KB)

5

From the serial console log, it seems booting successful w/o any hang issue.

It is not the device tree I requested.
Please run the following command on your board and share extracted_proc.dts as file here.

$ sudo dtc -I fs -O dts -o extracted_proc.dts /proc/device-tree

[    0.971665] 3100000.serial: ttyS0 at MMIO 0x3100000 (irq = 36, base_baud = 25500000) is a Tegra

Are you using /dev/ttyS0 for your UART device(LiDAR)?
It seems it is used for debug UART currently.

6

Seems like I can’t upload .dts file here, so here is the link of extracted_proc.dts file : https://drive.google.com/file/d/1JNkuAcbdVtnqOuolzBdeTDmigZlck9Jk/view?usp=sharing
No, I used /dev/ttyS0 to connect with my computer, because that is the only way I know to provide my serial console log. But when I first asked the question (Jul 27), I connect those pin (pin 8, 10) for my LiDAR. I guess it’s because those pins are used for debug by default? But I don’t know how to manage it, and I don’t know are there other pins are used for UART?

Thanks for your help!!!
The file here is I ran your command, and what it showed on terminal.
terminal text.txt (78.0 KB)

7

For debug serial console, please use UART interface from Serial Port header (J17).

image
image1310×347 46.7 KB

=> c280000.serial (uartc)

For connecting with your LiDAR module, please user UART interface from PIN8/PIN10 of 40-pins header.

image
image1690×105 20.4 KB

=> 3100000.serial(uarta)

You can run the following commands to prevent debug messages output from ttyS0.

$ sudo systemctl stop nvgetty
$ sudo systemctl disable nvgetty
$ sudo systemctl stop serial-getty@ttyS0.service
$ sudo systemctl disable serial-getty@ttyS0.service
8

Thanks for your reply,

I tried ran these four commands at terminal, and shut down Jetson TX2, and after it, I plugged in my LiDAR using PIN8 and 10 and tried to boot it, it will still hang at Nvidia logo screen, and still couldn’t enter the Ubuntu login screen.

Furthermore, I want to ask if there are other UART pins for my LiDARs, because I have three, I wondered if there are other pins for it, thanks.

Thanks for your help.

9

Please use debug UART from J17 for serial console log.

You should be able to use the UART from 40pins-header for your custom use case like LiDAR.
I would suggest you shorting PIN8/PIN10 to verify UART loopback test before connecting it with your module.

Yes, you can also try them.

You have 3110000.serial which should be from M.2 key E port.

[    0.973009] 3110000.serial: ttyTHS1 at MMIO 0x3110000 (irq = 37, base_baud = 0) is a TEGRA_UART
10

Thanks for your fast reply,

How to use debug UART from J17 for serial console log? Do I need to connect something? Because I don’t know have the pin diagram of J17.

Thanks for your help!

11

Please refer to this Table 19 and connect UART1_RX, UART1_TX and GND with the serial console cable connecting with your host.

13

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