Serial communication Serial interface
Digi XBee® 3 Zigbee® RF Module
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Serial interface
The XBee 3 Zigbee RF Module interfaces to a host device through a serial port. The device can
communicate through its serial port:
n Through logic and voltage compatible universal asynchronous receiver/transmitter (UART).
n Through a level translator to any serial device, for example through an RS-232 or USB interface
board.
n Through SPI, as described in SPI communications.
UART data flow
Devices that have a UART interface connect directly to the pins of the XBee 3 Zigbee RF Module as
shown in the following figure. The figure shows system data flow in a UART-interfaced environment.
Low-asserted signals have a horizontal line over the signal name.
For more information about hardware specifications for the UART, see the XBee 3 Hardware Reference
Manual.
Serial data
A device sends data to the XBee 3 Zigbee RF Module's UART 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 3 Zigbee 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.
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