DRIVE AGX Thor (SKU 12) - MCU VMON Undervoltage Fault (18V expectation vs 12V documentation)

[anusha.manila]

DRIVE OS Version: 7.2.4

Issue Description:

Hello NVIDIA Support Team,

We are currently setting up a DRIVE AGX Thor Developer Kit (SKU 12) on a development bench:

* Part Number: 670-63960-0012-000

* DRIVE OS Version: 7.2.4.0 (Build 7.2.4.0-0006 )

* Setup: Bench setup connected to a laboratory power supply.

#### The Problem:

Following the hardware guide, we connected the board to a 12V DC power source. However, attempting to flash the board using bootburn.py fails with a target recovery

error:

./bootburn.py -b p3960-10-sw03 -x /dev/ttyACM2 --init_persistent_partitions

...

\[bootburn\]: \[GetTegrasAssocWithAurix(514)\] : Setting Tegra-A in recovery...

\[bootburn\]: \[GetTegrasAssocWithAurix(532)\] : retrying board recovery check...

Could not put Tegra-A in recovery

OSError: 15

#### Safety MCU Diagnostics:

We connected directly to the Safety MCU console ( NvShell> on /dev/ttyACM2 @ 115200) to check the logs. During the reset sequence, the MCU immediately trips with an

undervoltage fault:

ERROR: NvMCU_SocVMON: UV fault has occurred !

ERROR: MCU_ERRHANDLER: SocVMON : ReportedID - 0x810B ErrorCode - 0x12

Running showvoltages reveals that the input rail KL30_PWR reads 12.33V but the Safety MCU expects 18.00V with a strict tolerance window of 17.10V to 18.90V:

showvoltages

Info: Executing cmd: showvoltages, argc: 0, args:

 ADCJxIy - Rail Name                 : Actual Voltage : Expected Voltage :  Voltage Range(default - +/- 5%)

...

ADCJ0I17 - KL30_PWR                  : 12.33V         : 18.00V           : { 17.10V to 18.90V}

ADCJ0I8S - SMCU_5V                   : 03.85V         : 05.00V           : { 04.75V to 05.25V}

#### Our Questions:

1. Why the 18V configuration? The official hardware specifications for the DRIVE AGX Thor DevKit state that the board operates on a nominal 12V input (operating range 9V to 16V). However, the factory-flashed MCU firmware actively enforces a 17.10V to 18.90V range, rendering 12V inputs as faults.

2. How to boot/flash on 12V? Since we are deploying this platform, we need to run on a 12V vehicle system.

 \* Is there a precompiled 12V-specific Safety MCU firmware binary ( .hex ) bundled in the DRIVE OS 7.2.4 SDK?

 \* If not, is modifying the guest safety manager device tree ( tegra264-gr.dts ) and building a custom configuration the officially supported path to change these  thresholds to  9V -16V ?

Thank you for your guidance!

[SivaRamaKrishnaNV]

Dear @anusha.manila ,
Could you please share

1. Host and target connecting wire pictures
2. Are you able to put the board in recovery from MCU console using tegrarecovery x1 on and tegrareset x1 . Please share complete log. After putting the board in recovery mode, you should see an additional NVIDIA device in lsusb on host. Please share complete log.
3. Please share complete showvoltages output
4. What is the current DOS version on target?

[anusha.manila]

The host and Target are connected via USB A to C as shown in the picture.

2. Reset errors out, log shown below

3. 
4. On Nvidia Drive Thor, I’m trying to flash Drive OS 7.2.4. currently connected to an NvShell prompt via minicom. No DOS available.
   The Host is a Linux PC.
   Linux rtx3090 6.8.0-124-generic #124~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue May 26 21:05:19 UTC x86_64 x86_64 x86_64 GNU/Linux

Note:
Nvidia Drive Thor SKU12 didn’t come with any power adapters and we are making it work in-house as shown below

We dont want to bump the voltage to 18V withoput official confirmation.

We have two Drive Thor units and both show the same exact output.

[SivaRamaKrishnaNV]

The connections looks good and you need to use 12V. Power connector details are at DRIVE AGX Thor Power Supply Specification - #4 by SivaRamaKrishnaNV
Are you able to access the target without any issue and only see issue when flashing? Noticed few issues in other power rails not with KL30x
Is it a newly received unit or it was working earlier?

[anusha.manila]

We resolved our bench setup issue by upgrading to an 850W power supply. However, after successfully flashing DRIVE OS 7.2.4, we ran into a new issue: the display setup wizard does not appear on boot.

Because the initial wizard is not showing, we are unable to accept the EULA and proceed with the initial configuration, blocking further setup.

Note: We have verified that the DisplayPort cable and monitor are functional and working correctly

Created another topic for this issue: DRIVE OS 7.2.4: Display setup wizard (oem-config) not appearing after flash

[SivaRamaKrishnaNV]

Dear @anusha.manila ,
Could you please share showvoltages on aurix console now.

[anusha.manila]

[SivaRamaKrishnaNV]

Now I see A2B_VDD and SOC0_CVM_PG looks good. How many watt was used earlier?

@anusha.manila

upgrading to an 850W power supply.