FIO + XBee current consumption during sleep

I think my FIO + XBee XSC is consuming too much current during sleep.

My application is sending a transmission once every ten minutes and sleeping in between. I'm using an Arduino FIO with the Narcoleptic library and an XBee XSC on pin mode sleep. I've added jumpers from FIO D2 and D3 to XBee DTR and CTS for sleep and ready status, respectively.

current consumption while in sleep mode: FIO w/o XBee = 0.045 mA XBee w/o FIO = 0.25 mA FIO + XBee = 0.75 mA!

For some reason, mating the XBee to the FIO causes the current consumption to more than double versus their standalone consumptions. According to the schematic, the only places where I could be leaking current is TX, RX, "RSSI" LED, "ON" LED, DTR. and CTS. The LED's are not on during sleep.

Before I start butchering my FIO can anyone suggest where that excess ~0.45mA of current might be going?


Possible current consumption contributor:

  • 3.3V regulator quiescent current (part number not provided in schematic)
  • Check pin 13 of the XBee and make sure it is low during sleep
  • Ensure XBee sleep mode is pin mode and not cyclic sleep
  • Brownout detector of ATMega328 not disabled
  • Floating pins of ATmega328

My FIO + Xbee is now down to 0.147mA in sleep mode. The only change I made was to remove the resisters for the "RSSI" and "ON" LED's. This doesn't really add up to my previous measurements, but I'm not complaining. I did try enabling pull ups for all of my unused pins, but that increased current consumption to .195 mA.

Update: I'm now down to 0.127 mA by disabling the BOD. I used this thread for the code to do it.