Hi Richard: A number of years ago I interfaced a PIC 16C63 with the Motorola VP+ Oncore, which at that time was the best timing GPS receiver, but it did have a bug in the sawtooth correction. The M12+ Timing GPS receiver is probably the best timing receiver you can get, maybe in the 10 to 30 ns absolute range. Although Trimble did pioneer in GPS, they used a patented receiver technique that greatly simplified the hardware and thus lowered the cost of the receivers, see my web page for more on that: http://www.pacificsites.com/~brooke/Trimpack.shtml But they have too few active channels. The problem is how the receiver handles setting and rising satellites. Does a receiver "hold onto a satellite" when there's a much better satellite available? The 12 channel receivers solve this problem and also give lower Dilution of x (DOP, DOT, etc.) because the solution is redundant. To try and answer your question, all the Motorola GPS receivers have a very powerful binary protocol that gives you access to about everything. The Trimble binary protocol does not give you access the the navigation data packets but Motorola does. All the Motorola commands start with "@@", and end with a checksum and see: http://www.pacificsites.com/~brooke/MOTGPS.html http://www.pacificsites.com/~brooke/AtAt.htm so it's pretty easy to get synched, even if you're not decoding all the packets. Because it's a binary format there is some stuffing and unstuffing needed, but it' spelled out in the docs. Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com >Date: Fri, 12 Mar 2004 17:44:09 -0700 >From: Richard Zinn >Subject: [PIC]: Interfacing a GPS chip with a PIC? > >Has anyone interfaced a GPS receiver chip, like the Motorola M12+ Oncore >receiver (http://www.synergy-gps.com/M12_Oncore_Timing.html)? Or maybe a >good website out there that describes how someone did it? Seems like I've >seen posts about this on this PIClist, but I couldn't find anything useful >in the archive. Maybe someone has an idea of another GPS receiver that >would be good to try and use with a PIC. > >Thanks. > > > > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.