Sleep mode timing not accurate ?


I’m a newbie in XBee programming. I’ve started building a simple temperature sensor ( LM335 ) attached to the AD0 pin of XBee, it seems to work fine until I’ve decided to use sleep mode. I’ve configured SP = 0x07D0 ( in theory, 20 seconds ) but the real thing is that my coordinator is seing sample data every 55 seconds.

My XBee Pro 2, is using ZIGBEE END DEVICE AT firmaware, v288C.

Things that I do not understand:

  • SM = 4 by default, but could be useful during development to have SM = 0 in order to avoid sleeping and do not have to use resets to wake up the XBee every time. Change is not possible in X-CTU or terminal using AT commands.

  • SP = 20 seconds, IR = 2 seconds, ST = 5 seconds, and SN = 1. So in theory the device is entering sleep mode every 20 seconds, reads sample data every 2 seconds during 5 seconds in order to grant at least 2 samples and sleeps again.

What I’m doing wrong ?

Details of XBee with firmware ZIGBEE END DEVICE AT 288C


First of all, try the newer 28A7 firmware. I’m not sure how long the 288C was out, and might have bugs.

The other possibility is - do you have the correct Sn/SP in your router/coordinator? If not, then some of your data productions will be LOST because when your device wakes, it is rejected by the parent and the IS data is lost in the process of rejoining. Check out this page:

check this tutorial its for newbies hope it work for you …

Updated firmware to latest version and changed coordinator configuration for AT commands SP and SN, according to the document provided. Now it works !!