Subdirectory to execute "in_power0_input" inaccessible?

[DeName]

Hello,
We’ve successfully read temperatures but are having difficulty reading power. Following the Jetson AGX Xavier Thermal Design Guide (v1.0 Oct 2018) pages 21 and 22,

we can get to the address directory (1-0040) but not further down (iio_device). The iio_device subdirectory is not listed, as shown in the picture below. Is there something that should be enabled to dig down further?

Thank you.

[KevinFFF]

Hi DeName.

Are you using the devkit or custom board for AGX Xavier?
What’s your Jetpack version in use?

Could you share the result of the following command on your board?

$ ls -l /sys/class/hwmon

[DeName]

Hello Kevin,

We are using a custom board (ConnectTech’s Rogue Carrier). When I asked the Software Engineers about Jetpack they shared with me that it is the “L4T Release” and the output below. Hopefully this helps answer this question and the “hwmon” question. If not, please let me know - thank you!

DeName

[KevinFFF]

Okay, it seems you are using custom carrier board with Jetpack 5.1.2(R35.4.1).

Please also share the result of the following command on your board.

$ ls -l /sys/class/hwmon

[DeName]

Hi KevinFFF, here is the output to $ ls -l /sys/class/hwmon :

[KevinFFF]

Then, you can run the following command to check the power.

$ sudo su
# cd /sys/class/hwmon/hwmon3
# cat in1_input 

[DeName]

Hi Kevin,

1. We got a number which seems high. Can you confirm this is the total power (in milliwatts) of all six rails (shown above) that the Jetson module itself is pulling?

2. What would be the command to extract the corresponding voltage?

3. What would be the command to extract the corresponding current?

We will subtract out the software-extracted total Jetson power from the benchtop power supply (benchtop = Jetson + custom carrier) to estimate the power the custom carrier board is pulling.

Thanks!

DeName

[KevinFFF]

There’re many sysfs nodes under /sys/class/hwmon/hwmon3 that you could just print each values. It includes the *_label to check what’s the meaning for that rail.

@DeName

What would be the command to extract the corresponding voltage?

# cd /sys/class/hwmon/hwmon3
# grep "" in*_*

@DeName

What would be the command to extract the corresponding current?

# cd /sys/class/hwmon/hwmon3
# grep "" curr*_*

You can just use Power GUI tool to check power usage.

[DeName]

I believe our software engineer printed all the values with this following result:

.

So here is the confusion:
a) If in7_label is millivolts, then are in1_input, in2_input, etc also millivolts (or milliwatts)?
b) If there are 6 power rails, why is in4_input (is this VDD_CV?) zero while curr4_input has current?
c) If there are 6 power rails, why are there only 4 currents (curr1_input to curr4_input)?
d) Is the only way to get the total power into the Jetson the summation of all the currents and voltages ie P1+P2+P3+P4+P5+P6 where
P1=curr1_input * in1_input
P2=curr2_input * in2_input
and etc?
Or is there another way to get total power into the Jetson in just one variable?

When I asked about the Power GUI the software engineer’s comment was that it was likely pulling these variables to print graphics - and we are currently not setup to do this if pulling the values via commands is easier.

Thank you,

DeName

[KevinFFF]

For questions a to d, I would suggest you referring to Jetson Xavier NX Series and Jetson AGX Xavier Series — NVIDIA Jetson Linux Developer Guide 1 documentation first.

@DeName

Or is there another way to get total power into the Jetson in just one variable?

You can also run sudo tegrastats instead of using Jetson Power GUI to check power usage.

May I know what’s your requirement and use case?