I'm planning on interfacing a GPS module to a mega32 AVR via the USART port. I haven't decided which GPS module to use yet. Suggestions? The SparkFun ones seem popular here.
Anyway, I don't quite fully understand the output sentences from the module. I want the time and lat/long information. Do I use the $GPGGA or $GPGLL sentence? Both seem to convey the same information (time, lat, long). Is the time listed in both, the time of the fix or the current time of day?
I need to keep track of the time of day. I assume I'll have to use the AVR's RTC to keep track of the time of day in case I lose the satellites. Correct? I'll use the GPS time (when available) to adjust the RTC.