Update GPIO output voltage and POR value

I’m trying to make two seemingly minor changes to the GPIO on the TX2: first, I want to change the output voltage of the GPIO11_AP_WAKE_BT signal to 3.3V; and second, I want the default output of GPIO12_BT_EN to be 0. I followed the steps of modifying the pinmux Excel file to generate dtsi files that I included in my device tree, but after some work in getting them to compile or work at all, they still didn’t result in either of the behaviors I want.

Perhaps these changes also need to be in the BCT cfg files? I generated those following the instructions for the pinmux-dts2cfg script, but the resulting files modify a lot more pins than the one I changed, and since the system boots reliably already, I’m loath to mess the bootloader.

So I have three questions:

  1. Should these changes be possible? If not, we're going to have to add level shifters to our carrier board.
  2. Do I need to make them in the BCT files as well? (Are there other places?)
  3. What is the command to flash the BCT files? I'm guessing ``` sudo ./flash.sh -r -k BCT jetson-tx2 mmcblk0p1 ```


Some GPIO have a 3.3V level shifter available via J24. See the carrier board schematic for details on which GPIO have this level shifter.

Not sure what changes you’d add to the dtb to make the default settings you want.

Thanks for the response, linuxdev. We are using our own carrier board that doesn’t have any level shifters. I don’t have it in front of me, but in the pinmux Excel file, you can select the voltage for entire blocks of certain gpio pins. I changed the DMIC_HV block to 3.3, and that is reflected in the pads file that is generated. The pin still only goes to 1.8V when I set it, however. My guess is that I need to attach it to 3.3V through a pullup. I was having trouble parsing this from the Parker TRM:
Enables open-drain pull-up capability to 3.3V thereby enabling High Voltage Operation. Enables 3.3V Receive. If E_IO_HV=1 is set, the pad can support 3.3V open-drain driving with I/O pull-up tolerance up to 3.3V and the Receiver is adjusted to 3.3V DC characteristics.

Any thoughts on setting the default value of a GPIO or flashing the BCT cfg files? It looked so simple in the pinmux file–just change Drive 1 to Drive 0.


hello r.jameson,

please download the [NVIDIA Tegra Linux Driver Package], and refer to [TX2 Configuring Pinmux GPIO and PAD] chapter in the [Release 28.2 Development Guide] for the BCT updates.