# How to use SPI? Can you tell me brief steps?

**URL:** <https://forums.developer.nvidia.com/t/how-to-use-spi-can-you-tell-me-brief-steps/124365>\
**Category:** Jetson AGX Xavier\
**Tags:** spi\
**Created:** [May 22, 2020, 3:06pm UTC](https://forums.developer.nvidia.com/t/how-to-use-spi-can-you-tell-me-brief-steps/124365 "2020-05-22T15:06:36Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\
**Post date:** [May 25, 2020, 5:00am UTC](https://forums.developer.nvidia.com/t/how-to-use-spi-can-you-tell-me-brief-steps/124365/3 "2020-05-25T05:00:54Z")

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Have a reference to below link.

> [@Spidev read failed on xavier devkit](https://forums.developer.nvidia.com/t/spidev-read-failed-on-xavier-devkit/118037):
>
> I want to use spi to read some device, so I enable spidev0.0, spidev1.0, spidev2.0. But there is no any signal on spi port when I test these port. my device tree: spi@3210000 { compatible = "nvidia,tegra186-spi"; reg = \<0x0 0x3210000 0x0 0x10000\>; interrupts = \<0x0 0x24 0x4\>; #address-cells = \<0x1\>; #size-cells = \<0x0\>; iommus = \<0x2 0x20\>; dma-coherent; dmas = \<0x1e 0xf 0x1e 0xf\>; dma-names = "rx", "tx"; spi-max-frequency = \<0x3dfd240\>; nvidia,clk-parents = "pll\_p", "cl…

> [@SPI1 not work on Xavier](https://forums.developer.nvidia.com/t/spi1-not-work-on-xavier/72141):
>
> I enable the spi1 and add spidev device node in dts. I can find the /dev/spidev0.0, but I can’t detect the signal with Logical Analysis. So, I want to know that the SPI1 is spidev0.0, right ?

> [@SPI works with JetPack 3.3 but not JetPack 4.2](https://forums.developer.nvidia.com/t/spi-works-with-jetpack-3-3-but-not-jetpack-4-2/72928):
>
> Hello, I have modified the device tree using JetPack 3.3 and managed to get SPI working, including talking to an actual SPI slave device from the TX2. However, I wish to use the latest JetPack 4.2 (to be up-to-date and because other features work in 4.2 that I do not have working in 3.3), but when I make the same changes to the device tree for supporting SPI with JetPack 4.2, the SPI no longer works. I see my changes to the device tree, the /dev/spidevM.N devices show up, and I can open/read/wr…

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