Getting access to SPI devices

Now, we are ready to manage real SPI devices. We can find tons of supported devices in Linux's tree that are usually grouped according to their specific operations in complete analogy to the I²C case.

In the next section, we will see several different kinds of devices all connected to the main CPU through the SPI bus. Also, we will use different embedded kits to test them, but as said earlier, every command can be easily repeated on every GNU-/Linux-based boards with a similar configuration.

LCD display

As the first example, we will use the following tiny LCD display, which can be used in simple applications because it's cheap and well supported by BeagleBone Black's kernel:

Note

The device can be purchased at http://www.cosino.io/product/color-tft-lcd-1-8-160x128 or by surfing the Internet. The LCD is based on the chip ST7735R, which has its datasheet at:  https://www.adafruit.com/datasheets/ST7735R_V0.2.pdf.

First of all, we must do the...