user2867: I have a Parallax PMB-688 GPS module I'm using with an Arduino and was wondering if I could hook up a compass directly to my GPS. The GPS has an RX port which I hypothesized a compass could be attached to but I don't know if the GPS would be able to comprehend the compass data alone or if I would need to hook it up to the Arduino separately. Please let me know if you have done this or know whether or not it will work. Thanks,
Chris

user2999: Unfortunately this will not work. If you take a look at the documentation for the module (here and here) you'll see that the RX pin is just there to receive commands for doing things like changing the baud rate and the protocol. The GPS wouldn't be able to comprehend the compass data.

2867: <p>I have a Parallax PMB-688 GPS module I'm using with an Arduino and was wondering if I could hook up a compass directly to my GPS. The GPS has an RX port which I hypothesized a compass could be attached to but I don't know if the GPS would be able to comprehend the compass data alone or if I would need to hook it up to the Arduino separately. Please let me know if you have done this or know whether or not it will work. Thanks,</p>

<p>Chris</p>
 2999: <p>Unfortunately this will not work. If you take a look at the documentation for the module (<a href="http://www.parallax.com/sites/default/files/downloads/28501-PMB-688-v0.1.pdf" rel="nofollow">here</a> and <a href="http://www.parallax.com/sites/default/files/downloads/28501-Polstar-NMEA-Commands.pdf" rel="nofollow">here</a>) you'll see that the RX pin is just there to receive commands for doing things like changing the baud rate and the protocol. The GPS wouldn't be able to comprehend the compass data.</p>
