Signal Processing Engine (SPE) SPI Sample Issues on Jetson Orin Nano Dev Kit

Issue Overview

Users are encountering difficulties with the Signal Processing Engine (SPE) SPI sample code for the Jetson Orin Nano 8GB development kit. The issue arises when attempting to utilize SPI2, as specified by the sample code, which requires specific pins on the J2 connector (260 Pin SODIMM):

• Pin 126 – CLK
• Pin 127 – MISO
• Pin 128 – MOSI
• Pin 130 – CS0

However, these pins are already assigned to other functions according to the schematic:

• Pin 126 – BT_M2_EN (Bluetooth enable)
• Pin 127 – PWR_LED_CTRL
• Pin 128 – W_DISABLE1_CTRL (Wi-Fi enable)
• Pin 130 – CAM_MUX_SEL

As a result, users cannot connect an SPI device, as the required pins are occupied. The issue occurs during setup when users attempt to flash the device and subsequently run SPI applications. The problem is consistent and significantly impacts user experience, as it prevents the use of SPI devices with the SPE firmware.

Possible Causes

• Hardware Incompatibility: The pins required for SPI2 are repurposed for other functionalities, making them unavailable for SPI communication.

• Firmware Limitations: The SPE firmware is designed to access only SPI2 from the AON cluster, restricting flexibility in using alternative SPI interfaces.

• Configuration Errors: Users may not be aware of the pin assignments or how they conflict with existing functionalities.

Troubleshooting Steps, Solutions & Fixes

1. Verify Pin Assignments:

   • Check the schematic for the Jetson Orin Nano dev kit to confirm pin assignments and their current use.

2. Explore Alternative SPI Interfaces:

   • Since SPI0 and SPI1 are accessible from J12 (40 Pin connector), consider using these interfaces instead of SPI2.
   • Ensure that any required changes in firmware or software configurations are made to accommodate this switch.

3. Modify Firmware Access:

   • If feasible, explore modifying or recompiling the SPE firmware to allow access to either SPI0 or SPI1. This may require advanced knowledge of firmware development.

4. Consult Documentation:

   • Review official Nvidia documentation regarding the Jetson Orin Nano and SPE firmware for any updates or guidelines on using alternative SPI interfaces.

5. Testing with Different Configurations:

   • Attempt to connect an SPI device using either SPI0 or SPI1 while ensuring that no other devices are conflicting with these pins.
   • Use terminal commands to gather system information and confirm that configurations are correct.

6. Best Practices for Future Use:

   • Always check pin assignments before beginning development on hardware projects.
   • Keep abreast of any updates from Nvidia regarding hardware specifications and firmware capabilities.

7. Community Support:

   • Engage with community forums or Nvidia support channels for additional insights or shared experiences from other users facing similar issues.

No specific code snippets or commands were mentioned in the discussion; however, users should be familiar with standard commands used for flashing and configuring devices on the Jetson platform.

Unresolved Aspects

The discussion indicates that there may be limitations inherent in the SPE firmware that restrict access to alternative SPIs. Further investigation into potential firmware updates or community-driven solutions may be necessary to fully resolve this issue.