AXIM & GPS USING SERIAL - Has it worked?

VirtualDoom · 01-30-03, 09:20 PM

I know a lot of people are getting their serial cables now, before I order mine and since my Axim isnt here yet, has anyone tried it with a GPS? I know someone just posted they used a null modem to hook up their nextel so it leads me to believe that it would work

John

JakeRich · 01-30-03, 10:20 PM

I have just unwrapped my serial cable, plugged it in to the Ax, connected it to my Magellan Meridian Gold, and voila! They found each other and happily communicated. I'm in my office in my basement, so the chance for an actual lock to any satellite is zero, but the Ax did find the Magellan, and reported that it had no fix. And I could watch the statements arrive using the Holux GPSMonitor.

I have a gender changer that I am 99% sure is a null modem, which I fully expected to have to use, between them. You will need that as well, but it definitely works!

VirtualDoom · 01-30-03, 10:36 PM

Thanks Jake!

I cant wait now, im going to order the serial sync so I can hook up my etrex!

John

Zarco · 01-31-03, 09:41 PM

Jake,

Where can I get the serial cable and null modem to hook up my eTrex to the Axim? Is there anything else I will need other than some sort of software (Streets & Trips, Mapopolis, etc)?

Thanks,
Zarco

JakeRich · 01-31-03, 11:32 PM

Get the Serial cable from Dell. It was about US$20. The Null modem you can get at any electronics store. Radio Shack has them, so would CompUSA. Then you need the serial cable for the Etrex. Check the Garmin site for that.

Software is largely a matter of taste. Mapopolis is the one I use, but others have other preferences. Look at gpspassion.com for comparisons and options.

One word: There is a discussion posted somewhere else either here or at pocketpcpassion.com about the serial cable needing DTR asserted. I didn't have any problems with it, and I know that the Magellan only puts out the two data lines, so I am assuming that the Null Modem took care of that. You can self-assert some of the RS232 signals, so the null modem may be crossing the lines and doing that.

This link is the discussion where the issue was raised. As I said, I didn't have any problems and all I have is the TXD, RXD and GND signals. I don't think any modding is necessary with a null modem but YMMV.

JakeRich · 02-01-03, 09:23 AM

Did a little more research. A true Null Modem crosses DSR and DTR. The AX is looking for DTR, and apparently asserts DSR. What all that means is that as long as you use a full Null modem connector, you should be fine. The Axim port will assert the very signal it needs, which gets reflected back by the Null modem.

tsulak · 02-01-03, 01:18 PM

sometimes my axim recieves gps data sometimes not, it there possibly a conflict using the com port? I shut down activesync, but that doesn't seem to help. Any ideas? my setup is a Dell serial sync cable, null modem adapter, gender changer, and pc cable for my etrex. I am really frustrated. When it does work I don't know why. I have tested my gps and it output nmea data with no problem. I have put all my cables and connectors on my ohms meters and everything works except communication between the two. Help!

Tim

Tom61 · 02-01-03, 04:08 PM

Quote:

null modem adapter, gender changer

Try switching which device plugs into which end of the adapters.

Midshipman Easy · 02-01-03, 05:31 PM

The null modem will NOT wake the dell serial cable chip up.. ive put an rs232 monitor and it is dead silent with or without a null modem.. wish it did though.

JakeRich · 02-01-03, 06:31 PM

Hmm. Curious. I have been out driving around for about 3 hours using my Magellan and Ax together. I use Mapopolis, and it has a GPS menu to start communications. I wonder if it somehow starts the communications protocols through Com1? I also tried the Holux GPS Viewer software and was able to see the NMEA statements streaming in after I enabled the GPS. Again, I wonder if it somehow asserts the DTR signal. My magellan only puts out pins 2,3 and 5 on the RS232, so it's not supplying the DTR (pin 4). I'm going to stop talking about this because I could jinx it if I do. ;)

tsulak · 02-02-03, 01:26 AM

What's the serial cable chip for, and how do I wake it up. It's luck of the draw for me to get my axim to communicate with my etrex. I am pretty sure I'm not missing something. What is DTR and how does it affect this? Thanks for the input.

Midshipman Easy · 02-02-03, 08:22 AM

tsulak .. check out my earlier posts on trying to get an axim to talk with a targus keyboard.. there are some links in there you can even read about the sipex chip.

http://www.aximsite.com/forums/index.php?a...t=ST&f=2&t=1610

tsulak · 02-02-03, 12:00 PM

Midshipman, (anyone)
Have you been able to trick the sipex chip to think your keyboard is supplying power? Also, I only want to use my serial cable to connect to my GPS, so is the chip in the middle still required? Thanks for all you input thus far.

Tim

Midshipman Easy · 02-02-03, 12:59 PM

Well if your GPS uses rs232 and not ttl to communicate youll need the chip to go active. I have no idea about the etrex gps your using, ive read gps's have worked just fine without any changes.. I gave the pdf to a friend of mine who is an engineering guru to see if i can shutoff this autopower saving feature by shorting something in there. Or if she can tell me which jumpers to short to make it go active. Im also following every thread i can find to see if someone else comes up with an answer first! Of course ill post here or in my targus thread any luck i have.

tsulak · 02-02-03, 06:16 PM

What's the difference between re232 and ttl communication? My thought is if I split the data output wire from my gps so that it goes the the data in pin on my axim cable and also the pin on the axim cable that will wake up the sipex chip then it should work. What pin would that be? I put my volt meter on my gps to see what the data output voltage is and it was just over 5 volts. What do you think?

Has anyone else had similar problems?

Thanks