munkee:
Dave,Can you elaborate more on:
I can send a "PMTK" string to my GPS to tell it to go to sleep, wake up every "x" and get reading.
Is this held within a datasheet somewhere? I couldn't see it when I was doing a quick skim of the adafruit examples. It looks like another item worth testing against my battery consumption readings instead of using the watchdog timer and going about it the other way around.
Ah...it's in the "confidential" document from G-Top. <Attached!>
You'll need to generate proper checksum values to include at end of commands. That can be done here -
http://www.hhhh.org/wiml/proj/nmeaxor.html
I'm still experimenting to decide which way is really better & most efficient -- MicroController waking the GPS, or GPS waking the MicroController. The *3339 GPS chipset (at least some of them, Adafruit version included) also have built-in data logging called "LOCUS", which can store up to 16 hours (based on one log every 15 seconds) of location data. Ideally, I would have GPS wake up every minute, (hour, whatever...) or so & save the location data. Then, wake up the micro controller once per day (or when has best chance of getting cellular connection), download data from GPS, and send it 'home' via GPRS.
PMTK_A08.pdf (405 KB)