raspberrypi/documentation — pull request #99 by notro (2014-07-22 15:05:57+00:00)
Title: Update spi/README.md

SDA doesn't figure in the text, only the datasheet.

According to http://elinux.org/RPi_BCM2835_GPIOs, SPI0 has only 2 chip selects.
The datasheet mentions a Chip Select 2 for the CS register, but this appears to be an error.