My application: xbee should be in a low power sleep mode. An external sensor should be able to wake it up if a signals comes in. Then after a while without activity at the sensor xbee should go back into sleep mode.
My not working “solutions”:
pin sleep: doesnt allow for using ST (time before sleep), thus xbee is triggered like it should, but shuts down immediately.
cyclic sleep: allows for pin wakening and the ST parameter, but the maximum sleep time is about 5 minutes. Waking it up every 5 minutes for i.e. 1 minute needs too much power.
What would I like to have would is either an “endless cycle” in cyclic sleep mode or the ST parameter in pin sleep mode, which both doesnt seem to exist.
Cyclic sleeps wakes it up every 5 minutes (latest). Then ST shuts it down after a minute (which I need). Thus the device is up for 20% of the time and thus needs 20% of the “active power”. This is ok, but too much compared to sleep mode (uA range).
Why not use Asynchronous Pin Sleep mode? This way you can sleep till you want to send data. You can even then control how long the radio is on thus reducing power even more.
As far as I know the ST parameter is ignored when pin wake is active. That means it shuts down immediately after pin goes back to zero (or one). I need a pin wake which just triggers the active state and after some minutes xbee should go into sleep mode again independent from the pin wake signal.
than what you want is SM 5 which is Async cyclic sleep with Pin wake. You could then set the SP time for 0x15F900 and sleep for a long time. You can then also wake with the sleep request line and remain awake for ST time frame.
I think I’ll try with an additional MCU (Attiny13). It solves several other problems like logic circuits which I also would need, and I have full flexibilty for a few uA.
Anyway thanks very much for your ideas!!
