Question about UART0 on the M.2 E Slot of Orin Nano Devkit

Robotics & Edge Computing Jetson Systems Jetson Orin Nano
1

Hi, Nvidia teams/

I have a couple of questions after reviewing the pin mapping documentation and reference schematics for the Jetson Orin Nano Developer Kit.

Jetson/L4T/peripheral/ - eLinux.org

The pin mapping documentation states:

“UART0 => UART2(PX04, PX05, PX06, PX07): uartb@3110000 (NA) - Unused => To M.2 Key E”

According to the reference schematics, UART0 is connected to the M.2 Key E slot.

My questions are:

  1. Does “Unused” mean that UART0 is disabled by default in the Device Tree?

  2. What is the intended purpose of connecting UART0 to the M.2 Key E slot in the reference design?

Thank you.

5

“Unused” means this UART is not used by the default software configuration; it does not mean the hardware connection is unavailable. The actual Device Tree status depends on your
JetPack/L4T release. NVIDIA previously confirmed that the M.2 Key E UART is not used by default. Related reply (https://forums.developer.nvidia.com/t/orin-nano-r36-4-uart0-
issue/333255/5)

The UART signals are routed to the M.2 Key E slot to support modules that require UART communication, such as Bluetooth modules using a UART HCI interface. Whether those signals
are used depends on the installed module; the connection does not imply that the supplied Wi-Fi/Bluetooth card uses UART. Related Bluetooth discussion (https://
UART0 flow control - #3 by KevinFFF)

6

understood. thank you!