Hardware Set-Up

• Freescale Freedom FRDM-KL46Z
• Arduino Wireless Shield
• XBee XB24-API-001

As the expansion pins on the Freedom board do not have headers installed it's necessary to solder some on before attaching the shield. I jerry-rigged a solution using some parts I had lying around but appropriate headers are certainly available from a variety of sources.

Getting Started

I used PuTTY (any function serial-enabled console will do) to monitor what my mbed application was sending to the XBee.

The Digi documentation for the XBee is pretty good from the point of view of getting up and running quickly.

Status

I've got a library which can set the XBee into API mode (the bullet points at the top of that page indicate the advantages of API mode) and exchange some API message packets and transmit data

My intent is that the library supports a relatively high-level API, for example a getFirmwareVersion() method rather than expecting the user to know what messages they need to construct and decode in order to query this information.

The library is Apache 2 licensed (as opposed to this other XBee library ).

Misc

X-CTU software - Digi's desktop SW for communicating with the XBee.

Issues

Flow Control

It looks as if flow control isn't supported on the KL64Z's serial interface yet.

Multi-Threading/RTOS

My goal is for the library to be thread-safe, however currently it is not suitable for calling within different RTOS threads.

Serial Monitor

As the shield uses the same serial TX/RX lines for communications between the uP and the XBee as are used for USB/serial comms to the PC, using "printf" to output status information on the serial connection can (does!) disrupt communication between the uP and the XBee. I did consider moving the XBee onto a different serial port in order to avoid this, but for the moment it's livable.

XBee Startup Time

Start-up time on the XBee seems longer than I'd have expected (but once it's "up and running", round-trip time on requests seem quite snappy). To be investigated at some point - could just be "the way it is" and fully documented in the data sheet.