Adjust ARM7 VDD

Hi everyone,

I got a bare metal application running on the ARM7/“BPMP-Lite” CPU and I would like to tune the voltage level for it.
What is the right voltage rail that powers this CPU and is there any information about the min./max. voltage limits available?

Thanks in advance.

Most documentation is available here (use the check box to limit to the TX1):
https://developer.nvidia.com/embedded/downloads

This requires a separate login and registration to download most docs…forum login is insufficient. You could then put “carrier” in the search box.

Generally speaking much of the I/O is 3.3V, some is 1.8V, and there is a jumper to select 1.8V or 3.3V on some of the I/O (default is 3.3V for the jumper position the carrier board ships with). I’m not sure if there is a rail suitable for powering an external device if that device consumes any significant current…you’d have to be more specific if you are talking about powering the device instead of I/O voltages.

Hi linuxdev,
I am just interested in tuning the actual ARM7 core voltage. I assume “VDD_SOC” (see “Jetson TX1 OEM Product Design Guide”) might be the VDD I’m looking for, however I could not find a confirming note in the documentation. That voltage is probably not controlled by the carrier board.

The TX1 is ARMv8-a architecture, the cores are ARM Cortex-A57, which are probably the cores you’re talking about. Is this for the Tegra SoC on the Jetson TX1, or perhaps something you want to be indirectly controlled by the TX1 (e.g., through sharing of a rail)?

No.
You are right, there are four ARMv8 cores. However, there is also an additional CPU that bootstraps those cores and usually runs the “bpmp firmware”.
http://http.download.nvidia.com/tegra-public-appnotes/tegra-boot-flow.html#_hardware_architecture
The ARM7 is also known as the BPMP-Lite, AVP or COP.

I don’t know how to access that core (or its rails).

Hi eigenvalue, the power rail to BPMP-L is VDD_SOC, rang is 0.68v~1.25v. But it is not exposed and is automatically controlled by DVFS scheme. We won’t provide the support of tuning it manually.