XBP09-DMDK Digi International, XBP09-DMDK Datasheet - Page 10

• Manufacturer Part Number: XBP09-DMDK
• Description: KIT STARTER PROMESH XBEE PRO
• Manufacturer: Digi International
• Series: XBEE-PRO™r
• Type: Transceiver, XBeePror

Specifications of XBP09-DMDK

• Frequency: 900MHz
• Wireless Frequency: 900 MHz
• Interface Type: RS-232, USB, UART
• Modulation: FHSS
• Security: 128 bit AES
• Operating Voltage: 3.3 V
• Output Power: 50 mW
• Antenna: RPSMA
• For Use With/related Products: Xbee-PRO Modules
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 602-1130

XBee‐PRO® 900 OEM RF RF Modules
GND
VCC
CTS
DOUT
RTS
DIN
Serial Flow Control
Serial Transmit
Receiver
Buffer
Serial
Buffer
Serial Receive Buffer
Serial Transmit Buffer
CTS Flow Control
Internal Data Flow Diagram
When serial data enters the RF module through the DIN Pin (pin 3), the data is stored in the serial
receive buffer until it can be processed. Under certain conditions, the module may not be able to
process data in the serial receive buffer immediately. If large amounts of serial data are sent to
the module, CTS flow control may be required to avoid overflowing the serial receive buffer.
Cases in which the serial receive buffer may become full and possibly overflow:
1. If the module is receiving a continuous stream of RF data, the data in the serial receive buffer
will not be transmitted until the module is no longer receiving RF data.
2. If the module is transmitting an RF data packet, the module may need to discover the
destination address or establish a route to the destination. After transmitting the data, the module
may need to retransmit the data if an acknowledgment is not received, or if the transmission is a
broadcast. These issues could delay the processing of data in the serial receive buffer.
When RF data is received, the data is moved into the serial transmit buffer and is sent out the
serial port. If the serial transmit buffer becomes full enough such that all data in a received RF
packet won’t fit in the serial transmit buffer, the entire RF data packet is dropped.
Cases in which the serial transmit buffer may become full resulting in dropped RF
packets
If the RF data rate is set higher than the interface data rate of the module, the module could
receive data faster than it can send the data to the host.
If the host does not allow the module to transmit data out from the serial transmit buffer because
of being held off by hardware flow control.
The RTS and CTS module pins can be used to provide RTS and/or CTS flow control. CTS flow
control provides an indication to the host to stop sending serial data to the module. RTS flow
control allows the host to signal the module to not send data in the serial transmit buffer out the
UART. RTS and CTS flow control are enabled using the D6 and D7 commands.
If CTS flow control is enabled (D7 command), when the serial receive buffer is is filled with FT
bytes, the module de-asserts CTS (sets it high) to signal to the host device to stop sending serial
data. CTS
© 2008 Digi International, Inc.
Processor
is re-asserted when less than FT - 16 bytes are in the UART receive buffer.
RF RX
Buffer
RF TX
Buffer
Transmitter
Receiver
RF Switch
Antenna
Port
10