How do I get the battery markings on the bottom of the board?
"Are the mounting holes at good spacing, .1" preferably but at least whole mm."Not sure what you are asking here.
"SQW signal going to an interrupt pin so you can create a version of millis() that doesn't skip a beat or have the RTC wake the processor at 3AM. "I think I can do that - does it need to a hardware interrupt like INT2 on pin PB2, or can it be a PCINT like PD7?
"3.3V regulator & cap"
is any one familiar with this Pericom part: PT7C4311WEX
One of those chips is extremely fine pitch.
QuoteOne of those chips is extremely fine pitch.I use a hot air gun to solder these (the FTDI is the finest I've done so far), easy, just run two beads of paste along the pads and hit it with the hot air. Clean any bridges with solder wick.
.. the 1284p is a low power device with <<1uA power save and power down.. Did you think on switching off the various chips on the board when they are not accessed? E.g. via a transistor in their Vcc.. Otherwise they can take ~mAmps.. A green board design..
..and what is interesting for a low power design is the system can measure its battery voltage in the way it will not consume much energy. So you need an op-amp (sourced from i/o pin or switched on/off when required) with fet intputs, and a high impedance voltage divider (not to discharge the battery too much). I am using MAX1724 3V3 stepup (great chip -sot23-5)and my system is powered from one nimh cell.. From time to time it measures the battery voltage.. The 1.2V cell is charged from a sollar cell.. It works from 0.6V (it shall work from 0.8V input voltage according to the datasheet)..P.
However as you are using a step-up regulator that would not apply as the vcc should be constant until battery exhaustion.