1.3 Interface with Slave Devices

The SPI module supports interfacing with one or more slave devices on the bus. It is important to note that when multiple slave devices are being used, each slave should have an independent Slave Select connection from the master. Each slave should have their own Slave Select line, and should be connected so that they all receive the SPI clock signal from the master device. Although the master always controls the SPI timing and provides the clock signal to all the slaves on the bus, only the slave that is selected will respond to the master. Once a slave has been selected by activating the Slave Select line, which can be active-high or active-low depending on the configuration, then it will respond to the master and can begin transferring data. The master device will have three signal lines that are common to all of the slave devices on the bus, and then a slave select line for each of the slave devices. It is important to refer to the documentation for the slave devices on the SPI bus to determine their requirements. Refer to the device data sheet for more information about connecting devices on the SPI bus. The four signal connections that are used by this SPI module are: