The Most Common XBee Mistakes

When it’s late at night and you just can’t get your ZigBee network working, more than likely a simple solution is waiting in the wings. Here are some tips for resolving issues typically encountered when working with XBee ZB (Series 2) radios and Arduino systems.

Common XBee Mistakes

If your project won’t work, check through this list of common mistakes that both beginners and experts make:

• Not using the correct firmware (choose coordinator, router, end device, and AT or API mode).
  
  
• Using ZNet 2.5 firmware, which is obsolete and will not interoperate with ZB firmware.
  
  
• Forgetting that AT commands use hexadecimals.
  
  
• Hitting Return after +++ (or otherwise not respecting the 1-second default guard times).
  
  
• Conversely, not hitting Return after an AT command.
  
  
• Letting the XBee time out of command mode before issuing an AT command (you’ll know because you get no response).
  
  
• Forgetting to write the configuration to firmware with ATWR (unless your application configures the radio interactively).
  
  
• Not using ATRE (restore factory defaults) before reconfiguring a previously used radio. Previous settings lurk unless you manually reset them all.
  
  
• Using a voltage regulator without decoupling capacitors (10 μF on input, 1 μF on output is usually good).
  
  
• Mixing up TX and RX pins. The fastest way to check this is to switch the wires and see if things start working.
  
  
• Trying to read more than 1.2 volts on the ZB analog inputs (1.2 V is the upper limit).
  
  
• Buying PRO radios when you don’t need them. Pros cost more, are bigger, and use a lot more battery power.
  
  
• Deciding the XBees are flaky. (You may not be using them correctly; they are very reliable.)
  
  
• Deciding an XBee is burned out when it’s set to a different baud rate. Check that the ON and ASSOC lights are functioning to confirm proper operation.
  
  
• Deciding an XBee is burned out when it is just sleeping. Check the ON light to see if it blinks occasionally.
  
  
• Forgetting to supply power or ground. (The ON light may go on and ASSOC light may blink, but both will be significantly dimmer.)
  
  
• Neglecting to check whether you are joined to the right network using ATAI to test for joining, and/or ATND to discover other network nodes.
  
  
• Not enabling rejoining for radios on smaller-sized networks (by setting ATJV to 1).
  
  
• Not contacting Digi sooner for support, especially if your radio seems dead or you keep getting an error you don’t understand.

XBee Arduino Mistakes

Here are a few more mistakes commonly made during XBee projects that work with Arduino:

• Sending values continuously without any delay. (Try a 10 ms delay in case you are overwhelming the receiving end.)
  
  
• Not removing RX and TX connections before uploading code. (Arduino will give an error.)
  
  
• Not removing the RX connection when resetting, if you are continuously receiving data. (Arduino will never reset.)