If I can get GPSapp working well for me, I want to permanently mount the StreetFinder in my car (preferably inside my dash somewhere with its antenna up close to the windshield so it can see the most satellites), but power is a question.

Its cig-lighter adapter is a straight line to a fuse, so I know it can run off of raw 12 volts.

It has a lithium-ion rechargeable battery in it, but I'd just rather have it be getting 12v external power on whenever the emepg is on.

Does anyone see a problem with wiring its power input directly to the player's Amp Remote line? How much current do you suppose it draws?

Got a multimeter?

The fact that it is battery-powered suggests that it's current draw isn't too great..If you know the capacity of the battery, and how long the battery lasts, then you can calculate it's current usage:

current (A) = capacity (in Ah) /battery life (seconds)

Now the type of voltage regulator in the 12V circuit will affect the current drawn under 12V. If the regulator is linear, then the 12V current will be similar to the above result. But this is inefficient - for a 5V device, 7/12 of the energy is disippated as heat, so either the unit of the adaptor will be noticeably warm if that is the case.

If the regulator is switching, then the 12V current is going to be lower than the battery current. eg, for a 5V unit, we only need 5/12 of the battery current to get the same power.

The amp remote is capable of driving 1A IIRC, so you should be fine. But before you hardwire your expensive GPS to it, make sure that the 12V regulation circuit is acutally internal, and not part of the adapter!

make sure that the 12V regulation circuit is acutally internal, and not part of the adapter!

I have dismantled the cigarette lighter adapter that comes with the GPS unit, and it is a straight wire and a fuse. That's all. No voltage regulation built-in.

So with that information, are you saying I should be fine?

It really shouldn't draw all that much, as it was designed to run off battery power.

What's the specs on the fuse? I'm not sure whether they have it to protect the car or the GPS, if it is 3A it's probably there to protect the car. But you could throw in a really low rated fuse (i.e. 250ma, or 500ma) then it should at least make sure that the GPS doesn't draw too much, and going from very low (100ma?) you could iteratively find exactly how much it draws.

You could just use a relay or a transistor to switch it off the remote line, then you wouldn't have to worry about the current draw as much...

Or just power it from the accessory line?

You could just use a relay or a transistor to switch it off the remote line, then you wouldn't have to worry about the current draw as much...

Thought of that. WAY more trouble than I want to go to.

I would be amazed if a handheld GPS required 12W of power - that's as much as the whole empeg uses.

Anyway, the RA line has an auto-reset fuse on it, so you shouldn't cause yourself any hassles if it did. Just remove the GPS and the fuse would reset. So you should be able to test the theory. I'd still check the specs / do the calculation, but that's just because of who I am...

Okie dokie.

GPS is now being powered off of the amp remote line. Guts have been removed from their plastic casing, wrapped in black tape, and stealth-mounted inside my dashboard above the empeg. Antenna is just beneath the dash plastic, above one of the A/C vents.

Seems to get decent reception and works OK as long as I've got the engine running. Overall low-voltage problems have always happened (battery icon) when the engine wasn't running, so it did not surprise me that reception was bad without the engine running.

I now have a working GPS system interfaced with the empeg. Total cost: $9.50 + hobby-time. If it weren't for this BBS, I probably would never have got a GPS and tried it.

My deepest thanks to:

- Derrick Brashear, who first notified us of the Staples clearance.

- Jan Harkes, who wrote GPSapp. It looks to be a very spiffy little application that will suit my needs quite nicely.

- Bitt Faulk for writing Preinit.

- Genixia, for the /programs0 creation script and helping with all my software questions.

I think I will take a drive now and see how the software works.

I think I will take a drive now and see how the software works.

Yup, that was my response

It works well, too! At least as good if not better than any of the Palm programs I messed with.

I've got a bit of a problem with the MapsOnUs data set, though. This has nothing to do with the software, which did fine considering that MapsOnUs was feeding it some rather bogus information. They had me on "UNNAMED ROAD" far too often, especially considering I was on a major multilane highway.

Wonder if there's any other web sites that we can learn how to screen-scrape? I'll go over to Programming and bring that up.

damn it. now i want one, since it's officially tried and tested. =)time to grab one off ebay for 20$. gonna research if the palmV version is better overall, since it seems like it also communicates using NMEA.

i'm a sucker for peer pressure.

I think any unit that spits out NMEA data will be fine.

The only wires I needed to connect to the thing were the power/ground, and three wires on the serial connector: Gnd, Tx, Rx. Then the GPSapp just worked (once I understood what its screens were telling me).

They had me on "UNNAMED ROAD" far too often,

I don't know a lot about how things work out there, but here state roads get an "SR" number (which is not the same as a numbered state route, but usually is the same number on such roads); Some townships use township road numbers, but not all. There are sometimes unnamed lanes but that's happening less and less as emergency service agencies require names so they can respond to incidents better.

If the road has no name and perhaps even if there is a consistent numbering system, TeleAtlas might not have the data.

Screen-scraping is only sufficient if you can figure out a way to rip DMS or UTM coordinates out somehow, either directly or by calculation.

Perhaps I missed this, but how did you interface the StreetFinder GPS to the empeg?

I don't know a lot about how things work out there, but here state roads get an "SR" number

No, I'm talking about major state freeways with full cloverleaf on and offramps, 2-3 lanes in each direction. Other mapping programs don't have any trouble identifying them, and they've been in place for decades. No excuse.

Perhaps I missed this, but how did you interface the StreetFinder GPS to the empeg?

That's the beauty of it. It was practically plug and play.

All I needed to do was know which pins on the connector were the RS-232 Ground, TX, and RX, and then connect those to the corresponding pins on the empeg's serial port. One brief moment of trial-and-error deciding whether to have TX/RX crossed or not crossed, and then it worked. All done.

(For anyone with a StreetFinder, I have a photo at home of which pins you solder to, if you want it. But it's easier to just figure it out yourself by looking at the pinout diagram. I don't have the link to the diagram any more but it was posted here on the BBS recently, I think in the original Staples Clearance thread.)

One brief moment of trial-and-error deciding whether to have TX/RX crossed or not crossed,

As a rule of thumb you can easily identify the true TX signal because it will give you a voltage (usually 5-12v) relative to Gnd, true RX on the other hand will read 0v.

It was easier just to swap the wires until the software seemed to like it.

Being in place for decades doesn't guarantee a name or a posted number.

Can you give an example of such a road, maybe post 2 endpoints we can enter into mapsonus and see such a route? I will admit to being curious.

Can you give an example of such a road, maybe post 2 endpoints we can enter into mapsonus and see such a route?

Yes, California State Highway 49 and California State Highway 20.

Example start and end directions:

National Hotel
211 Broad St
Nevada City, CA 95959

Shell Station
16978 Penn Valley Dr
Penn Valley, Ca 95946

Using those two addresses in popular search engines, you get...

MapsOnUs names significant sections of 49 and 20 as "unnamed road".

MapBlast is the simplest, giving only two directions. However it doesn't specify that you need to turn onto 20 at one point. See, when you start the journey, you are on a single stretch of highway that doubles as 20 and 49 together for a while. Later, they split off into separate 49/20 highways. Mapblast doesn't tell you about the split. Although it is accurate for it to just say "take highway 20", you might miss the turn if not directed to do so.

Mapquest is the most accurate, giving dead-on precise directions of each turn.