Does the OS know what voltage the SBC gets?

English Hardware
1

The Radxa Rock 5B single board computer uses a USB-c PD power supply. Depending on various things the SBC gets various voltages from the power delivery.

Does the OS know what voltage the system gets? Is it possible to see the input voltage somewhere in the file system?

2

@hukka what does it say on the Power Supply? Depends on the sensor chips, run sensors-detect --auto and see the output from the command sensors.

3

The PD unit delivers 60 watts at up to 20 volts.

  • The sensors-detect command basically shows Sorry, no sensors were detected.
  • Sensors shows temperatures. Composite and separate for sensor 1 and 2.
4

Did you run as root???

5

I ran both commands as a regular user first and then as root to see if there was a difference.

6

@hukka in the detect output, did you see any comments in the output of sensors found but no driver?

7

No, the only error I get is for a missing cpuID. The command looks for sensors but can’t find any. Could it be that there is no interface for i²c? The module i2c-dev loads successfully, though.

8

Here’s the command that was suggested at the Radxa forum:
cat /sys/devices/iio_sysfs_trigger/subsystem/devices/iio\\:device0/in_voltage6_raw

It doesn’t work on my system, but it might help trouble-shoot the problem.

9

@hukka iio is an i/o library https://wiki.analog.com/resources/tools-software/linux-software/libiio does the system have gpio outputs?

10

Yes, the Radxa Rock 5B has 40-pin GPIO.

11

@hukka so that is what that is related too then…

12

The system has iio-sensor-proxy installed… Does that help?

13

cpu-x is available in tumbleweed. Might help you.
Just find out the options (–help)

14

@hukka unfortunately not, I suspect there are no voltage sensors present…

15

cpu-x doesn’t show voltage, but an interesting tool nonetheless.

16

I have asked the Radxa forum the package name for accessing the iio stuff. It could well be that there is a misunderstanding, that they believe that I’m talking about the GPIO and not the system input trhough USB-c.

17

@hukka run it as root. If running as user the voltage is blank.

18

Running as root still shows a blank for voltage. Would the voltage be that of the CPU? I hope to find out the voltage of the USB-c input.

19

@hukka that the power pack connects to? If so, get a inline voltage/current tester (US$10 and up)? I have a number of them here…

20

So the answer seems to be no, the computer does not know what voltage it gets from the power delivery, although it would have been a good thing to have.

I’ll see if I can find an external meter that I’m happy with.