giantsfan3:
@buton:
As stated by @pylon above, given that you are using an SPI-based pressure sensor, the only way using the pressure sensor itself to make the inference about that threshold would be to take measurements once every X milliseconds/seconds, and go to sleep, unless threshold crossed. This is a reliable way to do it -- and draws hardly any power (actually negligible compared to the self-discharge of a Li-ion); remember that a microcontroller like on an Arduino processes the measurement (a few instruction cycles) in much less than a millisecond, and then goes to sleep, where the current draw is very close to zero.Also, a sidenote: just took a look at your webpage parts list for this project. You could REALLY cut down on the parts cost (and earn a little extra margin on your Kickstarter) if you make your own board instead of trying to assimilate all those individual modules (but you probably know this and have different reasons?)
Actually that will be my second goal after i finish my first prototype...
i know i can pack all in a small board and buy the components my self instead of getting them all preassembly, the first prototype i just want people who likes diy project be able to do it...
but i will follow your recomendation, as my second goald will be to put everything in one small board to save space and money :)...
this has been pretty helpfull you have a good point, checking the pressure every second will not take that much power.... 