In terms of SPI, the eUSCI A and B are capable of SPI communication in both three and four wire modes. In SPI mode, serial data is transmitted and received by multiple devices using a shared clock provided by the master. An additional pin controlled by the master, UCxSTE, is provided to enable a device to receive and transmit data. Some features of the SPI module include: 7 or 8-bit data length, LSB-first or MSB-first data transmit and receive, independent transmit and receive shift registers, selectable clock polarity and phase control and slave operation in LPM4.

