::[[File:pi3b-img264-1.png]]

<li><p>In the linux system, the SPI in the 40 pin is closed by default, and it needs to be opened manually before it can be used. The detailed steps are as follows:</p>

<ol style="list-style-type: lower-alpha;">

</li></ol>

<li>First check whether there is a '''spidev3.0''' device node in the Linux system. If it exists, it means that the SPI3 has been set. You can use it directly</li>

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</ol>

<li>Do not shorten the two pins of the SPI3 MOSI and MISO, and run the output result of the spidev_test as shown below. You can see that the data of TX and RX is inconsistent</li>

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</ol>

<li>Then the two pins of the SPI3 MOSI (No. 19 pins in the 40pin interface) and MISO (No. 21 in the 40PIN interface) run the output of SPIDEV_TEST as follows.You can see that sending and receiving data is the same.</li>