Serial port woes - anyone know the difference between PC &am

[nhorlock]

I am trying to use my Z to download data from my dive computer. The program works fine on my laptop and can receive data from the computer itself or from my palm IIIx (running dive computer emulation software). However on the Z it will only receive data sent by the Palm and not when it is sent direct from the Dive computer.

My guess is that it is one of two things:-
1) The voltage threshold on the Z is too high for my dive computer interface to drive.
2) The Z is more fussy about serial line signals than the PC.

Does anyone have any thoughts on this?
Anyone suceeded in connecting a Zaurus to an UWATEC Aladin dive computer?

Detailed Note:
Setup is a Z thin serial cable into either the palm serial cradle or a home made interface.
On PC the interface/palm plug directly in to the serial port.

Using a peice of serial scope software on the laptop and the Z I can see that DCD and CTS are raised when the palm sends but none are raised by the interface whether on the Laptop (works) or the Z (Doesn\'t work).

Any suggestions would be appreciated.

Neil

[yodabob]

Don\'t know about the dive computer, but I did have a similar problem when trying to control my telescope through the serial port.  Here\'s what worked for me:

Zaurus normally boots up in runlevel 5, which automatically starts a process called pppd that uses the serial port for PPP networking. This must be shut off before PSC can use the serial port for telescope control. The easiest way to do this is to perform a soft reset. A soft reset is nothing more than the procedure used for changing the Zaurus battery but this time we add one extra step. Note that a soft reset should not lose your addresses or other stored information but we take no responsibility if this happens anyway. Also, please read through all the following steps before performing them because one of them only gives you a few seconds to act.
quit all applications
just as you would if you were about to replace the battery, slide the switch on the rear of the Zaurus to the position labeled Replace Battery, wait a few seconds for the screen to go black, then return the switch to the position labeled Normal Operation.
slide open the Zaurus keyboard, locate the /? key.
turn the Zaurus on
Zaurus will now do a soft boot. Messages in white text on a black background will scroll by. After a few seconds the last message will be a line that says Wait ... and counts down from 5. Before it reaches 0 press the /? key. The countdown will stop and you will see a little menu. Now you can relax, the menu will just wait for you to type a key. Look through the entries and choose the one that makes /dev/tty0 free. On my Z this is done by pressing the e key, I hear from others it can be the t key, so your mileage will vary. Whatever it is, press that key now.
Zaurus will continue to boot as usual.

Note 1: This procedure need only be done whenever the device is soft reset. Just powering down or suspending the Zaurus during normal operation will not affect the availability of the serial port.

Note 2: to restore the PPP client, perform a soft reset again but just let the Wait message count down to 0 and let it proceed on its own.

[lardman]

The pppd daemon isn\'t run on OZ so the above post, though related, is not relevant.

Not sure why it won\'t work on your Z but will on the PC. Are you running Linux on the PC too?

What about your \'home made interface\'? Are you sure this is okay (as you say perhaps the Z is more picky than the PC)


Si

[nhorlock]

Cheers both for the replies. Lardman is right there is no other process locking the device.

The PC is running Mandrake 9, the interface (being my handiwork) is most likely to be at fault. However in its defence it works in most situations
Dive -] PC
Dive -] Palm
Palm -] PC
Palm -] Zaurus

The only thing that doesn\'t work is Dive Computer -] Zaurus.
The interface is not much more than an a signal amplifier to boost the signal of the dive computer. It boosts enough to be used by both the palm and the PC but if the Z is very particular then perhaps this is the problem. Is there anyway to determine the voltage levels at the interface without an external scope of some form?

I feel a trip to Maplins  might be in order, I\'ll grab a breakout box to be able to force a couple of signal high to match those seen when using Palm -] Z.

[lardman]

I guess you\'re running exactly the same software on both your Mandrake box and the Z.

You could try passing the dive computer output into your Mandrake box, then straight back out of another serial port and into the Z (should be simple enough to code up, or use some kind of serial sniffer program). This assumes you have 2 serial ports of course. This would eliminate any voltage problems, perhaps....

Not sure, good luck.


Si