Hi KevinFFF,
Thank you for your reply.
I am using the AGX Orin Developer Kit with no custom configuration. The only modification I made was enabling the SPI pins via jetson-io.py. I have since tested this on Jetpack 6.2 (L4T 36.4.3), and I’m still encountering similar issues with SPI performance.
Here are the details of my setup:
Model: NVIDIA Jetson AGX Orin Developer Kit - Jetpack 6.2 [L4T 36.4.3]
NV Power Mode[0]: MAXN
Serial Number: [XXX Show with: jetson_release -s XXX]
Hardware:
- P-Number: p3701-0000
- Module: NVIDIA Jetson AGX Orin
Platform:
- Distribution: Ubuntu 22.04 Jammy Jellyfish
- Release: 5.15.148-tegra
jtop:
- Version: 4.3.1
- Service: Active
Libraries:
- CUDA: 12.6.68
- cuDNN: 9.3.0.75
- TensorRT: 10.3.0.30
- VPI: 3.2.4
- Vulkan: 1.3.204
- OpenCV: 4.12.0-dev - with CUDA: YES
I’ve modified the spidev_test.c code from this repository to print the time it takes for SPI transfers (specifically the write time), and I keep getting values around 300 microseconds, with jitter present as well. Below is an example output:
$ sudo ./spidev_test -D /dev/spidev0.0 -v -p "TestTransferTime"
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 KHz)
SPI write took: 306 microseconds
TX | 54 65 73 74 54 72 61 6E 73 66 65 72 54 69 6D 65 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ | TestTransferTime
RX | FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ | ................
Even with higher frequencies (10 MHz, 20 MHz), the results remain the same. I am not testing loopback feedback—there’s nothing connected to the MOSI and MISO pins, so I am only measuring the transfer time itself. Is this method appropriate for testing?
Since I’ve encountered the same jitter and latency issues with both Jetpack 5.1 and Jetpack 6.2, I wanted to ask if the patch mentioned in this forum post would still be applicable to my setup. If so, could you provide some instructions on how to apply it?
Thanks again for your support!