Using a microprocessor to display GPS data on an LCD

**Zip-Lock** · 10-10-2002, 03:30 AM

Well I got my basic stamp II, wrote some code for it and finally got it all working. It’s really fast, from moment of turn on it displays GPS data on my Crystalfontz LCD within 4 seconds. Sometimes I have to wait a second from a cold start because my Gamin 35 takes up to 5 seconds get a valid fix.

My issue now is that I have maxed out the number of variable bytes I can use (26) on my Basic Stamp II. I would like to be able to display more data, because I have a 4x20 LCD to fill up, but I am out of RAM to do anything more.

I have latitude, longitude (had to crop down to minutes to conserve RAM), speed, and course (numeric) all displayed. I would like to add altitude and direction (N,S,E,W,etc) but I can’t process anything more without more RAM.

I’m sort of at a lost as to what to do at this point I got this far and now I’m stuck; I didn’t think I was going to max the BS2 out this easily. It’s looks like it would be fairly easy to add OBD-II support but I’m going to need something more powerful. Do I need to learn assembler to get anything more powerful?

Attached is a picture of what I have working thus far.

**[]\/[]aster []D** · 10-10-2002, 07:45 AM

im diggin those runnin shoes....

**Mxyzpltk** · 10-10-2002, 08:14 AM

I don't think you would need to learn assembler... just get a more powerful microprocessor.

The PIC devices are readily available and fairly cheap. They come in many different configurations, so you can get more or even outboard memory with relative ease.

There are a number of compilers available, several of which are based upon reasonably high-level languages and are free.

I haven't found the time to do much with my PIC programmer yet, so I can't be terribly specific, I'm afraid.

**Ohgary** · 10-10-2002, 03:00 PM

You might want to try the basicX stamp. This is very similar to the basic stamp but is faster and has more memory/variables.

Any change I can get the GPS code?

**SuperMatty** · 10-10-2002, 04:55 PM

Dude I can't believe you're showing latitude and longtitude...what is the point?

**Ohgary** · 10-10-2002, 04:58 PM

For day to day driving lat/long is of little use, but if your offroading or using a topo map these are needed. I know I would like to have them available, maybe not displayed all the time but sleectable when needed.

Originally posted by SuperMatty
Dude I can't believe you're showing latitude and longtitude...what is the point?

**Zip-Lock** · 10-10-2002, 07:26 PM

I want to display lat + long because I keep a mental map in my head and I can tell generally where I am or how far I have traveled from points I know.

Also another problem I was having with the lack of RAM was parsing NMEA sentences. With only 26 bytes RAM I could only use a fixed length NMEA sentence (GPRMC) and only capture strings at known points. With variable length strings like GPGGA (needed to get altitude) I would have to copy the string to RAM, search it, then parse out what I need.

I wish I had seen the BasicX before I bought the Basic Stamp II. I think I might have to send back my stamp and buy the BasicX instead. The BasicX looks like it not only has a lot more RAM but it runs faster too. So then I should be able to add OBD-II support too.

Any comments on the Basic Stamp II vs. BasicX?