All,

I have a very simple app for an 18F but this is the first time I have
used sleep mode or paid close attention to current consumption.  It is
battery powered and I'd like it to last as long as possible.

The board has a number of peripherals (a SHT temp/humidity sensor, MPL
pressure sensor, RTC and a RFM radio module).  However I am almost
positive that none of these are the cause of my problem, after a lot of
debugging.

The basic control flow is:

- initialise peripherals
- set RTC to give a 1 minute alarm interrupt
- configure falling edge interrupt on the RTC interrupt pin
- enter while(1) loop (application code will be here)
- sleep

The ISR just clears the interrupt, I have slimmed down the code
completely to isolate the bug.

The first time it enters sleep the current drawn from the battery drops
below 1mA, to 0.01mA on my meter (which probably be inaccurate, it's a
$5 special).  When it wakes the first time it spikes briefly and then
drops to ~2.5mA on the second sleep.  It never drops below 2.5mA again,
this is completely reproducible.

The only peripherals powered on during sleep are the RTC and the radio.
 The radio is definitely in its own sleep mode as otherwise it uses
>10mA.  Therefore I suspect that upon waking something on the PIC is no
longer initialised as I expect, which leads to the extra current
consumption.

Can anybody suggest places to start looking?

The shortest code that illustrates this is here:
http://pastebin.com/EtQbnvdx

David
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