XBee®/XBee‐PRO® ZB SMT RF Modules
EM357 Pin Mappings
The following table shows how the EM357 pins are used on the XBee.
EM357 Pin #
EM357 Pin Name
RST
XBee Pin #
Other Usage
12
18
19
20
21
22
24
25
26
6
Programming
PA7
8
PB3
29
25
16
17
14
15
32
Used for UART
Used for UART
Used for SPI
PB4
PA0 / SC2MOSI
PA1 / SC2MISO
PA2 / SC2SCLK
PA3 / SC2SSEL
PA4 / PTI_EN
Used for SPI
Used for SPI
Used for SPI
OTA packet tracing
PA5 / PTI_DATA /
BOOTMODE
OTA pacet tracing, force embedded serial bootloader, and SPI attention
line
27
12
29
30
31
33
34
35
36
38
41
42
43
PA6
PB1 / SC1TXD
PB2 / SC1RXD
PC2 / JTDO / SWO
PC3 / JTDI
7
3
Used for UART
4
Used for UART
26
28
5
JTAG (see Writing Custom Firmware section)
JTAG (see Writing Custom Firmware section)
JTAG (see Writing Custom Firmware section)
PC4 / JTMS / SWDIO
PB0
10
30
31
33
PC1 / ADC3
PB7 / ADC2
PB6 / ADC1
PB5 / ADC0
Temperature sensor on PRO version
NOTE: Some lines may not go to the external XBee pins in the programmable secondary processor version.
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, we recommend placing both a 1F and 8.2pF capacitor
as near to pin 2 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.
Note – For designs using the programmable modules, an additional 10F decoupling cap is recommended near
pin 2 of the module. The nearest proximity to pin 2 of the three caps should be in the following order: 8.2pf,
1F followed by 10F.
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.
© 2010 Digi International, Inc.
12
DCD [ DIGITAL CORE DESIGN ]
