I'm creating a "keyless" entry system using an nRF24L01+ and an AVR on both sides.
The base units power consumption isn't a concern, however the keys power consumption is.

The key will be powered by a CR2032 battery, and I would like to have an average consumption <14 µA.
I've played around with duty cycles, but I can't get the consumption low enough since every message takes about
25 ms from wakeup until the message bounces back.

The only solution I can think of is having another RF module attached which would handle nothing but wakeup.
It would be perfect if there is something like a passive receiver with a range of 1m-3m which would send an IRQ
when it receives a signal.

Do you have any suggestions?

 

Why would the power consumption of the key be a problem?

The button on the key is the power switch. Hence the key consumes no power when not being used. If your button is a soft power-on switch, the MCU should be placed into low-power mode for lowest power drain.

 

There won't be any button to push on the key, it's supposed to be what they
call a keyless system. It will react simply by approaching.

 

Why make life complicated? Put a button on the key.

 

Great answer. Thank you so much for your help

 

Anyone else?