Specifications
XBee®/XBee‐PRO®SERFModules
©2009DigiInternational,Inc. 12
EM250 Pin Mappings
The following table shows how the EM250 pins are used on the XBee.
Design Notes
The XBee modules do not specifically require any external circuitry or specific connections for
proper operation. However, there are some general design guidelines that are recommended for
help in troubleshooting and building a robust design.
Power Supply Design
Poor power supply can lead to poor radio performance especially if the supply voltage is not kept
within tolerance or is excessively noisy. To help reduce noise a 1uF and 8.2pF capacitor are
recommended to be placed as near to pin 1 on the PCB as possible. If using a switching regulator
for your power supply, switching frequencies above 500kHz are preferred. Power supply ripple
should be limited to a maximum 250mV peak to peak.
Recommended Pin Connections
The only required pin connections are VCC, GND, DOUT and DIN. To support serial firmware
updates, VCC, GND, DOUT, DIN, RTS, and DTR should be connected.
All unused pins should be left disconnected. No specific treatment is needed for unused outputs.
Other pins may be connected to external circuitry for convenience of operation including the
Associate LED pin (pin 15) and the Commissioning pin (pin 20). The Associate LED pin will flash
differently depending on the state of the module to the network, and a pushbutton attached to pin
EM250 Pin Number XBee Pin Number Other Usage
13 (Reset) 5 Connected to pin 8 on 2x5 SIF header.
19 (GPIO 11) 16
20 (GPIO 12) 12
21 (GPIO 0)
15
22 (GPIO 1)
XBee
Tied to ground (module identification)
XBee-PRO
Low-asserting shutdown line for output power compensation circuitry.
24 (GPIO 2)
XBee
Not connected. Configured as output low.
XBee-PRO
Powers the output power compensation circuitry.
25 (GPIO 3) 13
26 (GPIO 4 / ADC 0) 20 Connected to pin 9 on 2x5 SIF header.
27 (GPIO 5 / ADC 1) 19 Connected to pin 10 on 2x5 SIF header.
29 (GPIO 6 /ADC 2) 18
30 (GPIO 7 / ADC 3 17
31 (GPIO 8) 4
32 (GPIO 9) 2
33 (GPIO 10) 3
34 (SIF_CLK) Connected to pin 6 on 2x5 SIF header.
35 (SIF_MISO) Connected to pin 2 on 2x5 SIF header.
36 (SIF_MOSI) Connected to pin 4 on 2x5 SIF header.
37 (SIF_LOAD) Connected to pin 7 on 2x5 SIF header.
40 (GPIO 16) 7
41 (GPIO 15) 6
42 (GPIO 14) 9
43 (GPIO 13) 11