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== History ==
To verify the functionality of the library, a simple device (serial [https://www.micron.com/~/media/documents/products/data-sheet/nor-flash/serial-nor/m25p/m25p40.pdf NOR flash memory]) has been connected to the expansion connector (J33). Specifically, the SPI4 bus has been used. To build the example application using the library, the following version [https://developer.android.com/studio/index.html Android Studio] has been used:
<pre>
Android Studio 3.1
JRE: 1.8.0_152-release-1024-b02 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Android SDK API 27
</pre>
=== Wiring ===
[[File:SBCX-Android-4.4.3-SPI-hw.png|thumb|center|600px|Simplyfied diagram of the serial flash memory interfacing]]
As depicted in the previous image, the serial flash memory has been connected to the SPI4 bus by using SBCX's expansion connector (J33).
*The Linux kernel must support [https://www.kernel.org/doc/Documentation/spi/spidev spidev]
*The device file must have the permissions as shown in [[#Managing the device connection|this section]].
*The device tree must be modified in order to instantiate the SPI bus to be accessed: it is enough to enable the <code>escpi4</code> peripheral into SBCX device tree
<pre>
&ecspi4 {
status = "okay";
};
</pre>
