Thread: GPS DATA on HD44780 char Display ??

That's an interesting piece of equipment. But that doesn't do what I want.

I'm looking to take NEMA standard and output it from the PC to a character display. I'd like it to show lat/long and direction. That way, even when the GPS software is minimized I can still tell which way I'm going.

Yeah, that sounds about like what I want too.

long/lat & direction would be really nice.

Of course I'll have to get a new GPS [grumble]fraggin earthmate[/grumble]

what's wrong with your earthmate?

earthmate is not NMEA standard

IIRC the Earthmate has the same protocol as the tripmate, correct? If that is the case then it's very easy to convert it to NMEA standard (as I did)... The only difference is that these GPSs expect to hear "ASTRAL" on the com port before they will start dumping NMEA data... Luckily they are already broadcasting "ASTRAL" out approx once per second. So there is 2 hacks that you can do:

In both hacks you have to open her up and solder in a jumper between the DTR pin (RED wire, pin 4) and the +ve power pin from the battery harness, this will cause the tripmate to go "online" as soon as power is applied to it so that the other hacks can work. It's recommended to remove the red wire connection to the GPS once you do this.

Now you have 2 choices more:

1) Install a jumper between TX (black pin 2) and RX (brown pin 3) so that once the GPS powers on it will start broadcasting "ASTRAL", it will hear that and then switch to online mode and start broadcasting NMEA data. You need to remove the brown wire connection to make this work. Note that now you cannot send data to the GPS to configure anything (this is not normally needed anyway, but since these GPSs have a special "binary" mode (not NMEA compliant) that can give you a lot more information than just NMEA can, you might want to use option 2)

2) Don't do anything else, but before you start any GPS program on your computer, set up a simple script to send "ASTRAL" to the com port. Note that this will only work since the DTR pin has been removed and hardwired to be always-on. So once this is sent it will stay in full online mode broadcasting NMEA data until you power it off. This method requires you to do something special on the computer side before using any software, but it will allow you to retain the ability to talk to your GPS.

I did this to mine by the instructions from this guide and it worked like a charm, works great now with VisualGPS-XP and Streets&Trips 2002.

The #2 option is speculation from me and I haven't tested it yet, however I see no reason why it shouldn't work. Since I have no need to switch it into binary mode or configure which NMEA sentances it will send out I just did the full hack and left it.

It's powered directly from my +5V source on my power supply and works like a charm now. I hacked streets and trips to give me a 1second update interval and now I'm pretty happy. However I'm pretty ticked off at the limited ability for S&T to track and provide the driver with driving instructions. Does anyone know of a better program to use than S&T 2002?

This reply is a little late.. but the earthmate doesn't use NMEA data, it's totally proprietary, there is a small device you can buy to make the conversion.. but it isn't cheap. (though maybe cheaper than buying a new gps though)