Core Voltage

Has anyone found or know how to find the Core voltage of the Jetson TK1?
Thanks in advance!

Jetson TK1 schematic and layout are openly available so it’s easy to find the access to the Tegra K1 VDD_CORE. Perhaps the easiest way is to measure it on one of the power stage outputs.

Is there a pre-calculated value mentioned anywhere by Nvidia?

VDD_CORE can be measured on C2A5 or C9A6 capacitor in the schematic.

According to the table 44 of https://developer.nvidia.com/rdp/assets/tegra-k1-datasheet
VDD_CORE ranges
Use Case Model(UCM) #1 ( 20% operating time per day at max freq) : min 0.75V ~ max 1.26V (nominal 0.90V)
Use Case Model(UCM) #2 (100% operating time per day at max freq) : min 0.75V ~ max 1.12V (nominal 0.90V)

I just found this:

$ cat /sys/power/tegra_rail_stats
millivolts time
vdd_cpu (bin: 10.0mV)
0 0
800 5055
900 3
1000 0
1180 16103
vdd_core (bin: 12.50mV)
0 0
850 19835
875 402
900 563
912 11
950 0
975 22
1000 0
1012 325
1100 0
vdd_gpu (bin: 10.0mV)
0 0
1000 21161

I doesn’t tell the current voltage but it seems to tell how much time has been spent on each level so cat’ing it couple of times should show which one is currently being used the most.