Digi XBee SX 868 - SPI Communications

Operation Serial communications
XBee® SX 868 RF Module User Guide
52
Serial data
A device sends data to the XBee SX 868 RF Module's UART through pin 4 DIN as an asynchronous serial
signal. When the device is not transmitting data, the signals should idle high.
For serial communication to occur, you must configure the UART of both devices (the microcontroller
and the XBee SX 868 RF Module) with compatible settings for the baud rate, parity, start bits, stop bits,
and data bits.
Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit (high).
The following diagram illustrates the serial bit pattern of data passing through the device. The
diagram shows UART data packet 0x1F (decimal number 31) as transmitted through the device.
SPI communications
The XBee SX 868 RF Module supports SPI communications in slave mode. Slave mode receives the
clock signal and data from the master and returns data to the master. The following table shows the
signals that the SPI port uses on the device.
Signal Function
SPI_MOSI
(MasterOut,SlaveIn)
Inputs serial data from the master
SPI_MISO(Master
In,Slave Out)
Outputs serial data to the master
SPI_SCLK
(SerialClock)
Clocks data transfers on MOSI and MISO
SPI_SSEL
Enables serial communication with the slave