I'm putting the final touches on some XBee Series 1 sensors which will spend most of their time asleep. Because they're almost always asleep, this raises the question of how to reset them. This might be necessary if you want to change the PAN ID, for instance.
Ideally, it would nice if the sensors had a "reset to factory" button, but that does not appear to be possible. There is the ATRE command which does reset the XBee in the way I would like, but if the module is asleep, the command won't be received.
I see three possible solutions:
(1) If you want this kind of reset, remove the XBee from the sensor then use XTCU and some kind of "XBee Expolorer" as the interface to XBee. Taking the sensor apart and putting it back together this way is hardly ideal.
(2) Use SM=4, and have a "Cyclic Sleep Coordinator" send the ATRE wirelessly. I think this would work, although it appears that the remote/sleeping unit would use more power each time it wakes up because it always checks whether there's a message waiting for it, and that must take time, during which the XBee is using 50mA instead of 50uA. Since the only message that will ever be waiting for it is ATRE, this wastes precious battery power.
(3) Use SM=5 along with a button that sets Sleep_RQ (pin 9) LOW. Attach the sensor to a central unit using pins 2 and 3 for serial communication, de-assert Sleep_RQ, and send the ATRE command over the serial lines. I like this solution best, but it appears that Sleep_RQ is edge-triggered and not level-triggered, so it's not clear whether there would be sufficient time to send the ATRE over a serial line, particularly if ST=0 and SO=1 (to save power). The guard time alone (on the '+++') seems to preclude this approach.
Certainly, one solution would be to incorporate an XBee Explorer like device in the sensor, and another would be to control the XBee using a separate timing circuit along with SM=1 or 2, but that adds to the complexity and expense of the sensor.
Is there some other way to accomplish this goal?