[Unitree A1] HDMI Port of A1 does not work

General Discussion
1

We have discovered a more serious problem on our A1 robot. The front NVIDIA Xavier NX1 doesn’t seem to want to boot anymore. When we plug in an HDMI cable + mouse and keyboard, the monitor just stays black after we turn on the robot dog. The monitor does recognize that an HDMI device has been connected, but no NVIDIA boot icon or anything like that shows up. However, we can still connect to the robot via SSH using the IP 192.168.123.161. However, without a desktop view we can we can’t start any applications for our dog anymore or develop new applications on the dog in general. Can you help us there? Maybe this is a known problem and only a cable has come loose inside or the SD card has fallen out?

Attached you will find a video of the described problem:

2

Dear @bjoern,

On the mobile app does the A1 camera stream come? Also, once you ssh into the A1, could you tell us which IPs are available via:

sudo nmap -sP 192.168.123.*

as well as if you’ve sshed into the atom processor:

uname -a

We’ve never had a case where the SD card fell off. So it might be that instead, (assumption) some cabling is loose of the internal A1’s HDMI.

Also a few questions, did you test it prior and was it working before? Maybe try changing the cable and monitor to rule out external influences.

3

Hi @Sohail,

unfortunately, I can’t use the mobile app at the moment, we have disabled the WLAN access point function in the robot for one of our applications.

I can’t use NMAP as it doesn’t seem to be installed:

After typing uname -a I get the following response:
Linux unitree-UP-CHT01 4.4.86-rt99 #1 SMP PREEMPT RT Tue Oct 8 00:14:48 CST 2019 x86_64 x86_64 GNU/Linux

4

This is the atom processor, not the Nvidia, please try sshing to the ip with 192.168.123.12. Also, if possible try using your mobile camera phone check the front camera of the A1 to see if Depth camera is flashing (can only be seen by camera like how a remote IR is seen). Otherwise it seems that the Nvidia itself is not booting.

Also, was the Nvidia working before, or is this due to some recent changes either in software or hardware?

5

Hi Sohail,

sorry for the late reply. I did not notice I got a response already.

I tried sshing to the IP 192.168.123.12 but I got no response back. I also filmed the front camera and it looks like there is no flashing of the depth camera (I can post a video if you want to double check)

The Nvidia was working perfectly before, but suddenly from one day to another, the Nvidia wasn’t booting up again. We did not apply any changes to the robot’s hardware and did not change any software during the time the error occurred.

Regards,
Bjoern

6

Hi @Sohail,
Do you have any further information/help on this topic?

7

Hi @bjoern,

Pardon the late reply. It seems that there is some issue with the A1’s Nvidia. The fastest way that you can verify the Nvidia board’s integrity is by directly opening and checking, the instructions are provided here.

8

The issue might be loose cabling or perhaps the SD card jumping out of place, or perhaps the board is fried.

9

Hi @Sohail,

issue with the A1 still persists and I finally found time to take the robot apart. Seems that all cables are plugged in correctly. I found no SD Card so far but there was a correctly inserted M.2 SSD. We’re now trying to verify that the NX board isn’t damaged by installing it into a nano dev kit carrier board. So far there is no HDMI screen output.

Regards,
Jan

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