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Interfacing Digi OEM RF Modules to Microcontrollers

Digi radios are compatible with microcontrollers from a variety of vendors. For this reason, Digi does not make recommendations for choosing a specific microcontroller to interface with our radios. However, we can offer a few feature suggestions to consider. All Digi serial radios use a standard UART interface, making it important to also choose a microcontroller with a UART interface. The XBee WiFi, XBee 868LP, and XBee ZigBee SMT modules support a SPI interface in addition to the standard UART.

Many of the Digi modules have specific power requirements. Integration will be more seamless if a microcontroller with similar power requirements is used. For example, XBee modules require 2.8 - 3.4VCC input voltage, so it would be beneficial to choose a microcontroller with corresponding input voltage requirements. To be clear, the inputs to the XBee module are NOT 5V tolerant and cannot accept a voltage level higher than 3.3v on any pin. Applying a voltage higher than 3.3V will damage the module and void your warranty. However, the following modules operate at 5V or are 5V tolerant: XCite, XStream, XTend, XBee XSC (S3 Only)

For information on how to implement a 5V Digi radio (XStream or XTend) with a 3.3V microcontroller, please refer to the following resource: Low-Voltage Interface to OEM RF Module (3.3V).

If utilizing one of the surface mount (SMT) XBee modules, the XBee SMT module is designed to be soldered in place. This creates some unique challenges for troubleshooting and reprogramming the XBee. The primary means of updating and configuring the module will be via over-the-air configuration, however there are some factors that will cause the module to not be accessible in this way (bad firmware flash, unknown PAN ID, etc.) Reworking the module after it has been installed will void your warranty, so it is recommended to have a physical programming header installed on your board. This header will allow you to access the necessary pins of the XBee to configure the module or perform a recovery if needed. Note that two devices cannot share the same UART connection, so if a programming header is installed there should be some way to allow the header exclusive access to the XBee, either with a physical jumper or software solution. The recommended pin connections are listed in the manual.
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