SiRFIII GPS Logger Shield

The output from the EM-406a is in NMEA sentences. Each sentence starts with a '$'. There are a bunch of sentences that it can spit out, but only a few that we are interested in. For example sentences look at the EM-406a Manual.

Interesting sentences:

• RMC-Recommended Minimum Specific GNSS Data, message 103,04
• - this has all the basic data that you'd want for a boat; lat, long, speed (in knots)
• VTG-Course Over Ground and Ground Speed, message 103,05
• - this will give us the heading relative to magnetic north. That way we can directly compare the reading from the compass

Adalady has written code to test the GPS Sheild. There is also code for recording the GPS data and up to 3 analog inputs.