SPI naming conventions

Can someone explain to me why the numbers on SPI don’t line up in multiple places.

For instance, in the pin mux spreadsheet, on SOM pin 106 I see the Jetson Orin Nano Function listed as “SPI1_SCK” yet if I go over to customer usage and change what I want to use it for, it’s listed there as “SPI3_SCK”. I also notice in the 40 pin header config it is now listed as SPI3 as well.

How did SPI1 go to SPI3? Is there some kind of convention here to keep this all straight for me? Thanks!

Rick

Hi enc0der,

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

Please refer to the following table from design guide of Orin Nano.

SPI1_SCK is the name for the module.
GP36_SPI3_SCK is the name for the SoC.
=> They mean the same pin.

You could just refer to the design guide for more details.

Hey Kevin!

We are using three boards; custom board, XavierNX board (for HDMI) and Orin Dev board. Thanks for the pointer to where these are defined. Was curious why not use the SoC signal names since module is such an arbitrary connotation.

The reason I say is that these numbers get translated into 3 different values by the time they get to the user

For example:
SPI3 (orin) → SPI1 (module) → SPI2 (linux /dev)

I am using latest Jetpack 5.1.2

Do you mean AGX Orin or Orin Nano or Orin NX?

Since SoC is inside the module, you could just refer to the name for module.
SPI interface counts from 1 for linux node so that the SPI1(module) maps to spi2 in linux.

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