<li>First After restarting, enter the system to 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 up and can use it be used directly</li>

<li>Do not shorten short-circuit the two mosi and miso pins of the SPI3 MOSI and MISO, and run the output result of the running spidev_test is as shown below. You follows, you can see that the data of TX and RX is are inconsistent</li>

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