There are two ways to go about this. The SPI interface is by default no configured on the pins, because UART3/4 are mapped there. If you are not using Armbian, you need to manually change your devicetree to configure SPI pins. If you are using Armbian, you can use the boot-time overlay via your ArmbianEnv configugration as outlined here:
http://forum.pine64.org/showthread.php?t...3#pid25663
http://forum.pine64.org/showthread.php?t...3#pid25663
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