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-- Update on MarkSpace data cable (http://discussion.visorcentral.com/vcforum/showthread.php?threadid=9711)

I recently received a Mark/Space data cable for my Handspring Visor Deluxe. I have been using it with a Delorme Earthmate GPS receiver. My first impression was that it worked correctly but drained the batteries very quickly.

I have now noticed that when the battery gets down to about 80% that the VDX goes into HotSync mode. I can be in the middle of running the Delorme software Solus (1.5p) and it will detect a HotSync. I believe they are using the pullup resistor on the HS pin to power their RS-232/TTL converter, they must be pulling too much current and it pulls the HS pin low and start a HotSync.

I'm afraid that the Mark/Space cable is not going to be a viable solution if this is typical. Anyone else having problems with this cable?

I'm glad I went with WaC's cable!

I got a cable from WaC (a poster on these message boards) and it has performed flawlessly when I used it with Quo Vadis, Etrex GPS and VDX. I have also used it with other serial devices and noticed no battery drain. M

I guess I must try to convince WaC to make more cables!

Bye
AM


Ps: My experiences with the above are here:
http://discussion.visorcentral.com/...p?threadid=9736

i have a cable from WaC also and it works superbly. i've used it in my car with the etrex for about 6-7 hours straight before. his cable doesn't seem to drain the visor batteries nearly as much as the mark/space.

WaC, maybe you can make some money and teach the folks at mark/space a thing or two about cables...

Hey, in case you didn't know, DeLorme now sells cables designed for the Visor. They're available to buy from their website: http://www.delorme.com/earthmate/visor_pac.asp

Its out of stock (And $50, ouch).

__________________
Matt Nichols
[email protected]

quote:

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Originally posted by Nhatman
WaC, maybe you can make some money and teach the folks at mark/space a thing or two about cables...

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Question for wac

How much do you charge for the cables you make?

Rick

__________________
Rick

www.visorsolutions.com

WaC's Cable....

I've bought WaC's cable and also discussed manufacturing a whole bunch - WaC apparently does not have much time.

I have a friend who has a electronics hobby shop and I suggested he look into building WaC's cable. WaC did not seem to mind. The question is, if there is sufficient demand and - as WaC mentined to me - if there are any copyright/royalty problems in manufacturing for profit.

Bye
AM

I'd buy one right now!

Tech. Support at MarkSpace informed me that the Visor Platinum (what I have now) has less current available on the HS pin than the Deluxe and that that have experienced false HotSync's with the Platinum and Prism. They said that their next batch of cables (due Dec. 15th) have chips that require less current and he offered to exchange my current cable with a newer version. Maybe that will fix the problem?

Tim

I was selling the cables at cost for $16 shipped. It was enough to cover my costs for the parts, including the shipping and handling fees for Digi-Key and ATL orders. Now I've run out of ATL connectors, so I can't make any more cables unless you can supply the ATL connector. The minimum order is stopping me from buying more connectors.

I posted the design at my website for anyone to use at no charge. Anyone is welcome to sell the completed cables for profit, but I retain the copyright to the content on my website - all I ask is to be informed about its use.

Tim: that makes sense. The pullup resistors on those pins are a constant power drain. And it sounds like Handspring decided to use bigger resistors to reduce the current drain in the newer models, to offset the increased load from the faster processor and color display. But measurements will be needed to know for sure.

-WaC
Wayne

Comments on DataCord issue

Hi, I am the person at Personal Networking Technologies that designed the electronics in the cable being discussed in this thread. (PNT designs and manufactures DataCords for Mark/Space.)

I am concerned about the problems reported by Mr. Pearson, and am interested in getting this cable from him to see if there is something different about it compared with normal production (quite a few have been sold so far to Earthmate users, and this is the first of this type of problem.) I shall contact him separately about Fed-Ex'ing him a replacement cable.

My apologies to him for the problems with this cable.

***********************

The DCH-M9 design uses a SP3222 RS-232 chip. This chip has a typical quiescent current draw of 0.3mA, and a max of 1mA. This is the only component in the cable which consumes current. This small amount of current should not cause a noticable difference in battery life. I have measured the actual current consumption on a number of cables; they have been around 0.5mA.

I will post on this board to report the analysis of this defective cable.

Further investigation on current draw

I did some further study on current draw of a Visor with an Earthmate, in particular.

While the quiescent current draw of the RS232 chip is low (~0.5mA), there is more current required in order to carry out communication with the Earthmate. The measured amount of current out of the Visor is about 5mA. That is about right, for the current that is going into the Earthmate pins and the extra consumption that will be required of the RS232 chip to operate the capacitive voltage doubler to deliver the proper signal voltages to the interface.

Even 5mA does not sound like much. However, the Visor has to deliver that 5mA at a constant voltage (3.3v); and it uses a switchmode converter from the AAA's to do so. Very likely, the internal battery consumption is higher than 5mA when the AAA's are low.

Consequently, the current consumption of a cable that uses a RS232 chip (such as the DataCord) is going to be higher than a design such as wac's (see elsewhere in this thread), which uses inverters. The performance of a Visor with a RS232 chip is going to be similar to a Palm device - which has an RS232 chip onboard.

*****************************

So here's my recommendation. If you would like the absolute lowest current consumption, you would be best suited with a design such as wac's. On the other hand, if your application requires an RS232 chip (as is the case with the Earthmate), then you will find that our implementation is a very efficient example of that. However, the current consumption will be higher - about 5mA as mentioned before.

Thanks for enlightening us with the technical details about the Datacord HS. 5mA is low for a complete RS-232 circuit that contains two switching power supplies (�6V, I believe). Good work! I have experience in and appreciate how much work it takes to put a new design through mass-production. So I'd like to help as much as I can, if you don't mind.

My design was a quick-and-dirty solution for interfacing to handheld GPS', and also happens to work with external modems. Like I was trying to say above, you're welcome to use the inverter design (please - it will spare me from making more cables ).

I'm trying to figure out why the Earthmate requires a negative voltage - perhaps they use the handshaking lines? If that's the case, that may be one of your major current sinks. During my R&D, I remember seeing that the Visor will enter HotSync mode if the current drain on the HS1 pin exceeded a few mA - I'm afraid your design margins might still be a bit thin.

Thanks for your efforts,

-WaC
Wayne

P.S. I thought the purple Delorme and Mark/Space cords were a bit suspicious...

The Earthmate REQUIRES DTR to be active in order to send data from the Earthmate to the Visor.

I received a QUICK replacement of the Mark/Space data cable yesterday and tried it out with the Platinum and Earthmate GPS and everything works wonderfully (Thanks to Ben at PNT!). I have run the batteries down to 30% so far and haven't received a single false Hot-Sync.

I also downloaded Mark/Space's "Online" Terminal emulation program and it works great with the data-cord.

Tim Pearson

Glad the new design is working for you (and also that you like Online). These projects keep us quite busy!

FYI/FWIW: I'll be at PalmSource next week (speaking and attending) if anyone wants to meet for lunch or whatever.

__________________
Brian Hall, Mark/Space Softworks
Missing Sync, Mark/Space Mobile Office (Fax, E-Mail, SMS, Sketch, PhoneWatcher),
DataCord, Online VT100