Apex Quantum/Tusa IQ-700/Nitek Duo, has anyone made their own cable yet???

[TinoD'Voe]

I asked the same question several months ago and back then no one had yet found a DIY way of making this cable. Has anyone had success so far, would anyone be interested in having their own?

[dexter98]

I also couldn't find any schematic on the internet, so I did a little 2 dollar investigation on my own:

- The Apeks Quantum, Tusa IQ-700, Nitek Duo, Cressi Archimedi and Cressi Archimedi II all use exactly the same computer interface (all Seiko computers).

- The interface is actually nothing more than a USB-to-serial converter based on a PL-2303 from Prolific, which is used in many 'standard' USB-to-RS232 (DB-9) converters, and a level converter.

- The PL-2303 is however 'reprogrammed' to have it's own VID/PID (vendor ID/product ID; it is used to identify the type of the hardware).

- The software package supplied by TUSA also contians a Windows XP driver, from which the correct VID/PID can be retreived. VID=04b8 PID=0522 for the Seiko interface, while a 'standard' PL-2303 has VID=067b PID=2303.

- The pc-software connects to the USB device through it's VID/PID, so a 'standard' USB-to-serial converter cannot be used without reprogramming it. A simple programming tool is available from Prolific, but it is only available to suppliers and not to end-users.

- The pc-software from the Apeks/Tusa/Dive-rite does not have the connection tab in the options dialog and can therefore only connect to the USB device.

- The pc-software from Cressi (which also seems to be a newer version than the ones supplied by the other companies), allows to select a connection (USB / COM 1/2/3/4).

- If the serial communication protocol of all computers is the same and doesn't contain any product ID, a simple serial interface like already available for the Vyper, can probably be used for the communication in combination with the Cressi software.

So, not a schematic yet, but we certainly will come there! I'll keep you updated.

[dexter98]

Hmmm, I could als 'rebuild' the layout of the original PL-2303 in an AVR:

(like: http://www.obdev.at/products/avrusb/remotesensor.html)

This allows me to set the needed VID/PID. As I read the documentation of the PL-2303, it should be 100% CDC compatibel, so the needed USB 'layout' is known.

[zanedp]

Dexter98, what do you mean by this?

100% CDC compatibel, so the needed USB 'layout' is known.

What does "CDC compatible" mean?

And, what are you referring to by "USB 'layout'"?

[ComputerJoe]

Has anyone got the Cressi software?
I used to think that the pin out would be all we needed. But I realize there is an identification chip in the cable which the software looks for.

I can not believe that you could read the computer with a plain old serial (DB9-25) port. The throughput of USB is so much faster that what a standard serisl port can do. What BAUD rate would you even set the software to if you did get the pinouts.

Looks like we will have to belly up to that $180 bar. :-(

[dexter98]

Dexter98, what do you mean by this?
What does "CDC compatible" mean?
And, what are you referring to by "USB 'layout'"?

CDC means 'Communication Device Class' (see: USB communications device class - Wikipedia, the free encyclopedia). It is a certain class of USB devices which also contains a USB-to-serial standard.

However, the Prolific PL2303 is not fully compliant to this standard (the USB layout).

It also should be possible to mimic the exact behaviour of a PL2303 in a standard USB microcontroller.

[dexter98]

Has anyone got the Cressi software?
I used to think that the pin out would be all we needed. But I realize there is an identification chip in the cable which the software looks for.

I can not believe that you could read the computer with a plain old serial (DB9-25) port. The throughput of USB is so much faster that what a standard serisl port can do. What BAUD rate would you even set the software to if you did get the pinouts.

Looks like we will have to belly up to that $180 bar. :-(

The original cable is nothing else than a USB-to-serial converter with a custom ID and a special output circuit (level shifter), so other software doesn't see it as a serial port. The original software looks for this USB-to-serial converter with this custom ID. (Actually many low-speed devices uses a USB-to-serial converter internally, since for many application speed is not needed at all).


However, speed is by far not an issue at all, since the divecomputer communicates at a 'whopping' 4800bps (yes, bits-per-second!... which is roughly translates into 480 bytes per second!) and this speed is hardwired into the divecomputer. It takes quite a lot of time for dives to transfer.


I have this up and running... I have downloaded all my dives from my divecomputer this way... I know the protocols (both the USB protocol and the divecomputer protocol) inside out.... so try believe me something else

[saxplayer1004]

so is there any chance we could like buy one of these cables from you :-D