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Would this work?? Or am I dreaming??


jollybgood

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I've been trying to figure out a way to hook up my GPSV to my Pocket PC Phone (Audiox Thera which is basically a Toshiba built unit).

 

The Thera seems to be red headed step child of Pocket PC's when it comes to connectivity. Toshiba wants 240 bucks for the cable that would hook up to the Pocket PC to a USB Device. (assuming I could use a PDA serial-to-USB adapter to hook it to my GPSV). That's forty bucks MORE than the PPC cost me.

 

I noticed Toshiba sells a Serial Cradle for the Thera for sixty bucks. Here's my crazy idea.

 

I use the Serial Cradle as a Dashboard mount and attached the end of the cable to a GPS Serial adapter (14 bucks -- for connecting a PDA serial cable to a GPS Serial cable according to the website I found it on). THen I hook up the GPSV serial cable to the other side of the adapter.

 

Would this allow the two to communicate?

 

I about to give up trying to find a solution. A 240 dollar calble is just too much money. Especially since I can buy a Teletype or Pharos GPS kit for the Thera for the same amount of money.

 

Jolly R. Blackburn

http://kenzerco.com

"Never declare war on a man who buys his ink by the gallon."

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quote:
Originally posted by GeckoGeek:

Would http://www.mobileplanet.com/private/pocketpc/product.asp?cat_id=201&cat_name=Connect&dept_id=2330&pf_id=MP730872 work?


 

You know I saw that and wondered about it. But there's no information on what sort of connector is on the other end.

 

Too bad there's no photo. icon_frown.gif

 

Thanks for pointing it out though.

 

Jolly R. Blackburn

http://kenzerco.com

"Never declare war on a man who buys his ink by the gallon."

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quote:
The Thera seems to be red headed step child of Pocket PC's when it comes to connectivity.

 

Welcome to the world of the Toshiba/Audiovox non-partnership. My Genio e550G falls into the same boat. icon_smile.gif

 

quote:
I use the Serial Cradle as a Dashboard mount and attached the end of the cable to a GPS Serial adapter (14 bucks -- for connecting a PDA serial cable to a GPS Serial cable according to the website I found it on). THen I hook up the GPSV serial cable to the other side of the adapter.

 

This should work fine, I believe. I do almost the same thing with my e550G. I have a serial cradle in my Durango. The serial cable from the cradle (which I would normally plug into a PC) goes into a small null-modem adapter and then that connects to the serial cable for my Magellan MAP330. They all work fine together.

 

I'm not sure what that $14 "GPS Serial adapter" is unless it is just a null-modem adapter. If that is all it is, then you should be able to get them online for like $3. They are cheap.

 

If it is something else, I'm not sure why you would need it. Basically, you should be able to connect the cradle's serial and GPSV's serial together with just a null-modem adapter and be all set.

 

- John...

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I looked on e-bay and the null modems were F/F null modem cables.

 

You'll need a M/M Null Modem. I looked for one about a month ago but ended up having to get a DB9 M/F null modem and a M/M gender changer both from Radio Shack. The total cost was around $12.00. I use this to connect my eTrex using the serial cable to my iPAQ using the serial port on the cradle. It works like a charm with G7toCE.

 

Ducks - Flying, great tasting, geocaches of meat

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quote:
Originally posted by Jolly B Good:

I noticed Toshiba sells a Serial Cradle for the Thera for sixty bucks. Here's my crazy idea.

 

I use the Serial Cradle as a Dashboard mount and attached the end of the cable to a GPS Serial adapter (14 bucks -- for connecting a PDA serial cable to a GPS Serial cable according to the website I found it on). THen I hook up the GPSV serial cable to the other side of the adapter.

 

Would this allow the two to communicate?


Maybe. The question is does either device plan on using the power from a computer to run the interface? If so, it won't work since the power won't be there.

 

You might try googling for "Thera cable". That's how I found the prior link.

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quote:
Originally posted by Rubberhead:

I looked on e-bay and the null modems were F/F null modem cables.

 

You'll need a M/M Null Modem. I looked for one about a month ago but ended up having to get a DB9 M/F null modem and a M/M gender changer both from Radio Shack. The total cost was around $12.00. I use this to connect my eTrex using the serial cable to my iPAQ using the serial port on the cradle. It works like a charm with G7toCE.

 

Ducks - Flying, great tasting, geocaches of meat


 

Thanks, I found a male-male null modem on PCMall.com. Ordered the serial cradle from CARtronics.

 

Hopefully I'm in buisiness. I'll let you know how it turns out.

 

Jolly R. Blackburn

http://kenzerco.com

"Never declare war on a man who buys his ink by the gallon."

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quote:
Originally posted by GeckoGeek:

Maybe. The question is does either device plan on using the power from a computer to run the interface? If so, it won't work since the power won't be there.


 

Um, huh? What power? We're talking serial here. No device should be drawing power from anything on a serial port. That is not standard and not "allowed" really. There is no +5v source on a standard serial pinout, for example. You'd have to be drawing power from one of the pins intended for other purposes -- which would not be recommended.

 

In any case, he doesn't have to worry about this. Neither his PocketPC nor his GPS are going to be expecting any sort of "power" out of the serial connection.

 

- John...

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quote:
Originally posted by John & Bretta:

Um, huh? What power? We're talking serial here.


 

Yeah, but at what voltage level? Some "serial cables" actually contains a TTL-level to RS-232 level translation circuit. (They can be molded into a DB-9 plug.) Such circuits tend to draw power from the RS-232 lines supplied by the computer to power themselves.

 

I know zilch about the Thera or the PPC's interface. I'm speaking from general knowledge of interfacing serial devices. If both devices output true RS-232 voltage levels, then you should be OK. But if either one of them relies on the cable to do some level translation then there could easily be "issues".

 

The presence of a conversion circuit could be why the cable is so expensive. It's not just plug and wires.

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quote:
Originally posted by GeckoGeek:

Yeah, but at what voltage level? Some "serial cables" actually contains a TTL-level to RS-232 level translation circuit.


But, in this case, neither his serial cradle or the cable going to the GPS would be doing that. Both are designed to attach to normal PC serial ports -- and therefore cannot rely on them for power. They are made to plug directly in. Therefore, nothing (as far as translation circuits) could fall in between.

 

quote:
The presence of a conversion circuit could be why the cable is so expensive. It's not just plug and wires.

But in this case, he's using the cradle instead. The cradle, designed to be plugged directly into a PC serial port, would have to be safe for him to use like this. IMO.

 

So, he should be all set...

 

- John...

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quote:
Originally posted by John & Bretta:

But, in this case, neither his serial cradle or the cable going to the GPS would be doing that. Both are designed to attach to normal PC serial ports -- and therefore cannot rely on them for power. They are made to plug directly in. Therefore, nothing (as far as translation circuits) could fall in between.


Unless you’ve read the technical specs for the unit it’s hard to tell. The translation circuit can be so small that it fits into what looks like a normal cable. I think the cable for my StarTac phone is like that. The tech spec for the phone says it’s TTL level, but the ordinary-looking cable connects directly to a computer’s serial port.

 

I don’t know what GPS is involved here. Garmins are OK. The big question in my mind is the PDA-phone.

 

No harm in trying, but success is not guaranteed.

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quote:
Originally posted by GeckoGeek:

Unless you’ve read the technical specs for the unit it’s hard to tell.


I disagree. I don't hvae to read the technical specs of the PDA to know that there is almost no chance that it is drawing power out of one of the pins on the PC via its cradle. It would be against spec to do so. It could damage the PC to do so. The chances that Toshiba/Audiovox decided to do try to pull any non-negligable power out of the serial port of an unknown PC are pretty much nil. They wouldn't do it.

 

quote:
The translation circuit can be so small that it fits into what looks like a normal cable. I think the cable for my StarTac phone is like that. The tech spec for the phone says it’s TTL level, but the ordinary-looking cable connects directly to a computer’s serial port.

 

I would be quite surprised if this is true (provided that, to support the TTL circuit, it is drawing the power from the serial port). Maybe it does have such a cable -- but I would guess that, if they are drawing power to run it, they are drawing it from their own phone end -- not the unknown PC end. Again, it is very unlikely that they are drawing significant power (even to run a simply TTL circuit) from the PC's serial port. At least, at any level where it would matter and/or be harmful to pull the same power from anything else connected.

 

quote:
I don’t know what GPS is involved here. Garmins are OK. The big question in my mind is the PDA-phone.

 

No harm in trying, but success is not guaranteed.


I guess we can agree to disagree from this point on if you still think it might be a problem. If it works, great. If it doesn't work, I highly doubt it is due to some power draw from the serial cable within the cradle. It just isn't going to happen...

 

- John...

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thanks for all the thoughts and advice folks.

 

Guess the only way we'll really know is when my cradle and null modem arrive next week. I'm hopeful it'll work.

 

I did read on a newsgroup however that Verizon and Sprint had Toshiba cripple the 2032 (Thera) so it can't be hooked up to a laptop and used as a wireless modem. Not sure if this is true but who knows -- it could complicate matters.

 

Since there are several serial GPS units for the Thera however, I'm thinking it should work.

 

Jolly R. Blackburn

http://kenzerco.com

"Never declare war on a man who buys his ink by the gallon."

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quote:
Originally posted by John & Bretta:

I disagree. I don't hvae to read the technical specs of the PDA to know that there is almost no chance that it is drawing power out of one of the pins on the PC via its cradle. It would be against spec to do so. It could damage the PC to do so.


Beg to differ. Most RS-232 driver chips are current limited. You can short out the port without damaging it. Each pin of a typical desktop can supply about 10mA of current. I've freqently run LEDs off the 232 port for diagnositics. Take a look at the driver Spec Sheets.

 

Let me try another angle. RS-232 requires some “odd” voltages. +5 is easy to get. +12 isn’t bad. But you have to get either –5 or –12V. That’s a problem. Now either you can build a circuit that takes the phone’s battery and transforms it to the needed voltages, (bulky) or you steal the voltage off the handshake lines of the RS-232 port you’re interfacing to so you can send the proper voltages back to it. That’s what’s happening. Take a look at these circuits. It barrows just enough power off of the port to feed the port the voltages it expects to see. But if that port is a Garmin without handshake lines, it may not work.

 

It's not a complex circuit and all it needs is a few mA to run. But it does need power. Nothing that a 9V battery can't do. icon_cool.gif

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quote:
Originally posted by GeckoGeek:

Let me try another angle. RS-232 requires some “odd” voltages. +5 is easy to get. +12 isn’t bad. But you have to get either –5 or –12V.


Indeed. Actually, nominal for the chip you mentioned is 9v and -9v. So, I agree -- it gets odd.

 

quote:
or you steal the voltage off the handshake lines of the RS-232 port you’re interfacing to so you can send the proper voltages back to it. That’s what’s happening.

I guess you know more about it than I then. I found it very unlikely that the serial port for his Thera is pulling ~9v from the PC's serial port... But, I guess it COULD be happening.

 

But, if you know that is what is happening, then I guess I have to concede -- since I didn't think it was.

 

Regardless, I still say his setup is going to work fine -- or, if it doesn't, it'll have nothing to do with cable power requirements... icon_smile.gif

 

quote:
Take a look at these http://www.qsl.net/ok1rr/control.html. It barrows just enough power off of the port to feed the port the voltages it expects to see.

Agreed -- he's using the RTS pin's output to power the circuit. I was always under the impression that this was "not allowed" when it came to PC serial ports. Not that it wouldn't work, of course -- just that you weren't supposed to do it for real circuits. But, again, I certainly could have been mistaken on that.

 

quote:
But if that port is a Garmin without handshake lines, it may not work.

Agreed. IF they built it to use power from the other end, AND the other end isn't providing power out of whatever pin they are using, then it might not work.

 

Seems quite unlikely though. But, yes, possible -- provided that such circuits are "allowed" in such applications.

 

- John...

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quote:
Originally posted by John & Bretta:

Agreed -- he's using the RTS pin's output to power the circuit. I was always under the impression that this was "not allowed" when it came to PC serial ports. Not that it wouldn't work, of course -- just that you weren't supposed to do it for real circuits.


 

I think that’s the major point of our disagreement – and that we’re both right. If you’re talking ‘RS-232 Spec’ you’re probably right in that you’re not supposed to draw any power. (What is “spec”? – it’s between a terminal and a dumb modem. Everything else is bastardizing it.) But if you’re talking about what a lot of portable interfaces do to take advantage of the common desktop interface, and avoid the problems of createing proper RS-232 voltages then I’m right. The general public doesn’t really care about “proper”; they just want it to be cheap, compact and work. Some interfaces don’t work with laptops or adapters and I’m guessing that’s why.

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quote:
Originally posted by Jolly B Good:

thanks for all the thoughts and advice folks.

 

Guess the only way we'll really know is when my cradle and null modem arrive next week. I'm hopeful it'll work. (snip)


Interesting thread. Question: Why not build your own null cable with components from, for example, Radio Shack?

If asthetics are not important (molded connector), this seems a faster/cheaper way to go, and allows length customization.

 

As for RS-232 specifications, I guess that's why it's still RS, and not an IEEE standard. RS=Recommended Standard. icon_smile.gif

 

don

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quote:
Originally posted by Cachetrotters:

Interesting thread. Question: Why not build your own null cable with components from, for example, Radio Shack?


Hopefully his time is worth slightly more than $2 for a part plus a few bucks shipping. icon_smile.gif

 

quote:
If asthetics are not important (molded connector), this seems a faster/cheaper way to go, and allows length customization.

Heck, with my experience from Radio Shack, after you pay just for the molded connectors and a bit of wire in between you're already going to be above the $5 you could probably buy a nice one for online...

 

quote:
As for RS-232 specifications, I guess that's why it's still RS, and not an IEEE standard. RS=Recommended Standard. icon_smile.gif

True, true! icon_smile.gif

 

- John...

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Okay, so I got the serial cradle today and my null modem. Hooked everything up to my Garmin GPSV and my Pocket PC. Crossed my fingers and....

 

it WORKS!!! Hoody Hoo!!

 

IT was so simple. At least three vendors online told me the THera simply couldn't be hooked up to a GPS like this. I'm so glad I didn't give up.

 

It seems to me that should work with any PPC and serial based GPS -- but what do I know?

 

This has left me scratching my head though. I looked at a LOT of solutions posted on various websites which explained how to hook up a PPC with a GPS. Almost ALL of them involved adding a USB adafter to the PPC and then a USB-to-Serial PDA adapter to the cable and hooking that up to your GPS cable.

 

Why fuss with USB at all if both devices are serial based? I'm just curious. It seems like your converting to USB on the PPC side. and then BACK to serial with the adapter. Seems a bit strange. Maybe I'm missing something here.

 

Jolly R. Blackburn

http://kenzerco.com

"Never declare war on a man who buys his ink by the gallon."

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quote:
Originally posted by Jolly B Good:

it WORKS!!! Hoody Hoo!!


icon_cool.gificon_cool.gificon_cool.gif

 

quote:
It seems to me that should work with any PPC and serial based GPS -- but what do I know?
Let's not go there. John and I beat that horse pretty good.

 

quote:
Why fuss with USB at all if both devices are serial based? I'm just curious.
Beats the heck out of me. Enjoy the toy.
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Yes, as say Rubberhead & others, you will need a NullModem.

Second way (in this way I connected my Meridian to Palm m125): you just buy the serial hotsync cable and change the connector (from female to male costs some 0,5 USD±), and connect the pinouts as in NullModem. Worx good and costs merre pennies icon_smile.gif

Third way (not proofed, but should work): buy the serial "Modem Cable", if avaible, for your PDA/Smartphone and serial cable for GPS and enjoy.

Mix_

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