Reverse engineering the Xcalibrator 1 -- serial port to PC
I bought a used Xcalibrator from Thomas (blkout) but he listed it thinking he knew where the PC cable needed to download the unit was -- but he still can't find it. I do have the cable needed to hook it to the truck.
He sent me the unit though, so I took it apart and figured out how to add a standard 9-pin cable and a power jack so I can download tunes into it without the $50 cable that you have to buy to do that normally.
There's pictures of the somewhat "hacked" looking result, lol. However, it works and I've downloaded sample .xtr tunes into it to test it.
The reason I want that so bad is that you can use ExtremeTune software that is free from SCT to modify the tunes. You can change shift quality, VSS calibration and other things and get much of the function of an Xcalibrator 2 and do it on the PC with graphs and so on. I may do a second topic on this when I start using it to actually tweak the tunes I've bought.
If anyone's interested in how I figured this out, I reasoned like this to begin with:
1. PC communications is a "standard". It's different than OBD2 communications and would use different circuitry.
2. They are probably using different pins since there are 15 pins on the connector and Ford OBD2 ports require less than that for programming the PCM.
3. It's a small box so likely they used a standard chip to interface that doesn't take up much room.
Examining the circuit board, I found it had an MA3232C chip right near the connector. It was Texas Instruments' version of the MAX3232 RS-232 transceiver. Bingo!
The chip provides two signal outs, and two in. One of them was always at -5 volts and that identified it as the RS-232 transmit data line. Its paired receiver I figured was the receive data line.
So far so good, but the ExtremeTune software signals the box using a handshaking line. Just hooking up transmit and receive yielded an "Excalibrator loopback not detected" error (or something like that). Obviously, one of the "handshaking" signals from the 9 pin connector for the PC would have to connect to this remaining input line.
So I put a meter on the lines and kept telling ExtremeTune to communicate with an Excalibrator 1 and that allowed me to identify the pin by looking at which one changed.
It doesn't seem to need the other input pin on the Excalibrator, but I connected it anyway based on what I thought it should be hooked to.
I ran the lines to a 9-pin female "D" connector (DB-9F) and mounted that on the box as shown.
It works, and I don't need a $50 cable! If Thomas finds it, great -- but it's no longer necessary.
You also need 12 volts to the unit when using it with a PC. I put a "pigtail" on it with a standard coaxial power connector and I can use a "wall wart" transformer that puts out 12 volts DC to power it.
I didn't buy anything to do it. Just used junk I have lying around.
Last edited by n3elz; 03-04-2007 at 05:14 PM.