My project don’t need gps coordinates, only time.
It should have easy way to get time to I2C.
I would like to use GPS for time, because it’s so accurate.
What small SparkFun GPS you recommend?
Whatever your wallet can handle.
A halfway decent GPS unit will pull in a good time fix long before it’ll track a good lat/long.
Hi,
The vast majority of “GPS modules” use a serial port to output their time/position data, so that is your best bet. I did a quick search of the Sparkfun site, as well as external resources, and did not find any GPS modules with an ‘i2c’ interface. What processor/platform are you using for your project? I’ve used both the EM-406 and EM-408 GPS modules, and both work well!
Tell us more about your needs!
John
sparrow:
I would like to use GPS for time, because it’s so accurate.
Just remember that the message you get from the GPS with the time in it was for a time in the PAST! It took time to compute the time, create the message, clock it out, and time on your end to receive it. For GPS modules with a Pulse Per Second (PPS) output, that pulse is generated at the moment the time is computed. Hence when you get the message, that time is for the previous PPS pulse.
Most GPS modules will have a very accurate PPS signal. Often there will only be on the order of 50 to 100 nano seconds of error (jitter) on that pulse. Using hardware counters you can average this jitter out over many minutes (for a non moving receiver) and get time accurate to better than 20 nanoseconds.
One persons accurate may be another persons useless. Compare the disk jockey announcing the time on the radio (± 5 minutes) to having your very own atomic clock calibrated to NIST standards (sub fento second accuracy).
Well as for the I2C issue I know that the [Venus GPS has the capability to output data through custom firmware.](http://www.sparkfun.com/products/11058)
I recall most UBLOX GPS had a i2c as well