| Author | Message | ||
     Ted Lavino Moderator Username: tlavino Post Number: 89 Registered: 01-2006 |
Greetings folks a great graphic of the Garmin 4 pin interface and the laptop RS-232 interface: http://www.tapr.org/~kh2z/Waypoint/Connections.htm | ||
| David Sheriff Board Administrator Username: admin Post Number: 227 Registered: 01-2004 |
If this whole interface subject makes your head hurt you are probably normal. If not, you might be an engineer. | ||
| David Sheriff Board Administrator Username: admin Post Number: 224 Registered: 01-2004 |
I have an unresolved NMEA 0183 issue that I will outline in this space. My Furuno 1923 radar has a 0183 input for navigation data. It will display this data together with the radar PPI display in several combinations. I have tried to hook up a handheld GPS to the device with no luck. My suspicion is that Furuno, being Furuno, actually designed their 0183 inputs to the 0183 specification. I suspect, but have no proof yet, that the Garmin chartplotter we have as a demo unit for class will accept the input from a handheld GPS, Garmin being Garmin. In other discussion we have noted that handheld GPS units put out a serial data stream equivalent to NMEA 0183, but do not conform to the electrical interface. This works with PCs because they don't conform to the interface either. Specifically, 0183 requires the signal to go below 0 volts as well as above. As handhelds are powered from two penlight cells, 3 volts, they are lucky if they meet the positive voltage swing required by 0183. They have no source of negative voltage to swing the other way. I have been meaning to wire up an interface that will take what comes out of a handheld GPS and convert it to real 0183 to answer the question. All in good time. . . . Probably when we get to the subject of interfacing in class, which is going to make some students very confused. | ||
| David Sheriff Board Administrator Username: admin Post Number: 223 Registered: 01-2004 |
We might as well get this subtopic up because NMEA 0183 can be really confusing for newcomers and sometimes for old hands alike. I will post the link to our 2006 discussion which is pretty enlightening. It also answers the question I hint at in the readings when I suggest that the Garmin interface article is not completely accurate in its claims, although it does work. |
