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MarkEagle,

I just figured something out. If you use a wire (paper clip) and short pins 2 3 and 4 together all at once. That is when the error ocurrs. I wonder if KBD should be low while the HS1 is being set low with the button? Is there something missing in the circuit here? I don't know why it works if the sync has been activated previously and the cable not disconnected?

Just a thought Any other EEs out there with knowledge of the Visor internals?

According to some info I got from Handspring, pin 3 (HS1) is momentarily tied to pin 4 (GND) via the cradle button for both serial and USB sync's. Having pin 2 (KBD) tied to pin 4 tells the Visor that the sync is serial. In their cradles, pin 2 is "open" on the USB and "closed" (ties to GND) on the serial.

In my cable design, I have 2 permanently tied to 4 in the ATL connector (after all, it IS a serial cable) and I use a N.O. momentary push button switch connecting 3 to 4 to initiate a sync. I'm not sure what happens if 3 is tied to GND continuously. I can also start a sync by tapping Local Sync in the HotSync app.

In your case, is 3 tied to GND? If so, maybe this is your problem.

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MarkEagle - Ice is nice!

I found the problem, it was software. My circuit works great.

Thanks for the help!

Great news!!! If you're interested, there's some more info in another thread I started last night. It contains some details provided to me by Handspring Developer Support.

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MarkEagle - Ice is nice!

I got the same email. Check out what I posted at this here: http://discussion.visorcentral.com/...TML/000192.html
I explain exactly what is meant buy the difference between TTL and RS232. This is old news since we have a working serial cable. Now we have to put it to some good use. I am trying to test the idea of connecting any GPS handheld unit to the visor and/or Pilot (since it is the same OS) using serial. That way we don't use up the slot. I would like to save it for an mp3 player or better things.