XBP24-BPIT-004 Digi International, XBP24-BPIT-004 Datasheet - Page 13

• Manufacturer Part Number: XBP24-BPIT-004
• Description: Zigbee / 802.15.4 Modules XBee-PRO Znet 2.5 PCB Antenna
• Manufacturer: Digi International

Specifications of XBP24-BPIT-004

• Rohs: yes
• Frequency Band: 2.4 GHz
• Line Of Sight Range: 100 m
• Data Rate: 250 Kbps
• Sensitivity: - 102 dBm
• Operating Supply Voltage: 3 V to 3.4 V
• Output Power: 63 mW
• Antenna Connector Type: PCB
• Maximum Operating Temperature: + 85 C

XBee ZNet 2.5/XBee‐PRO ZNet 2.5 ZigBee OEM RF Modules v1.x4x
CTS
DOUT
RTS
DIN
2.1.3. Serial Flow Control
Serial Transmit
Receiver
Buffer
Serial
Buffer
Serial Receive Buffer
Serial Transmit Buffer
CTS Flow Control
Figure 2‐03. 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:
When RF data is received, the data is moved into the serial transmit buffer and sent out the UART.
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
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 17 bytes away
from being full, the module de-asserts CTS (sets it high) to signal to the host device to stop
sending serial data. CTS is re-asserted after the serial receive buffer has 34 bytes of space.
© 2008 Digi International, Inc.
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 desti-
nation 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.
1.
could receive data faster than it can send the data to the host.
2.
because of being held off by hardware flow control.
Processor
If the RF data rate is set higher than the interface data rate of the module, the module
If the host does not allow the module to transmit data out from the serial transmit buffer
RF RX
Buffer
RF TX
Buffer
Transmitter
Receiver
RF Switch
Antenna
Port
12