XK-Z11-M Digi International, XK-Z11-M Datasheet - Page 27

• Manufacturer Part Number: XK-Z11-M
• Description: ZIGBEE MODULE DEVELOPMENT KIT
• Manufacturer: Digi International
• Series: XBee™r
• Type: Transceiver, 802.15.4/ZigBeer

Specifications of XK-Z11-M

• Frequency: 2.4GHz
• For Use With/related Products: XBee Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 602-1184

© 2010 Digi International, Inc.
2. RF Module Operation
Serial Communications
The XBee RF Modules interface to a host device through a logic-level asynchronous serial port. Through its serial
port, the module can communicate with any logic and voltage compatible UART; or through a level translator to any
serial device (for example: through a RS-232 or USB interface board).
UART Data Flow
Serial Buffers
Devices that have a UART interface can connect directly to the pins of the RF module as shown in the figure
below.
Serial Data
The XBee modules maintain small buffers to collect received serial and RF data, which is illustrated in the figure
below. The serial receive buffer collects incoming serial characters and holds them until they can be processed.
The serial transmit buffer collects data that is received via the RF link that will be transmitted out the UART.
Data enters the module UART through the DIN (pin 3) as an asynchronous serial signal. The signal should
idle high when no data is being transmitted.
Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit (high). The
following figure illustrates the serial bit pattern of data passing through the module.
Serial communications depend on the two UARTs (the microcontroller's and the RF module's) to be
configured with compatible settings (baud rate, parity, start bits, stop bits, data bits).
The UART baud rate, parity, and stop bits settings on the XBee module can be configured with the BD, NB,
and SB commands respectively. See the command table in chapter 10 for details.
System Data Flow Diagram in a UART‐interfaced environment
(Low‐asserted signals distinguished with horizontal line over signal name.)
UART data packet 0x1F (decimal number ʺ31ʺ) as transmitted through the RF module
Example Data Format is 8‐N‐1 (bits ‐ parity ‐ # of stop bits)
DOUT (data out)
DIN (data in)
DOUT (data out)
DIN (data in)
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