pcmhacking.net

Hey guys, New to the arena here..
Tons of reading material.

Anyway, ill keep this short and not waste your time.

I've built a makeshift ALDL cable using an arduino uno clone from Freetronics..http://www.freetronics.com/products/eleven on board it uses a small FTDI chip to program the arduino
Thus ive removed the arduino (atmega) chip and I'm trying to use the FTDI (atMega8u2) to talk directly to the PCM

I've bridged the RX/TX ports and I'm linking the earth from the FTDI to the PCM earth to prevent float issues.
As the FTDI outputs at TTL voltage, I haven't put a transistor or any resistors in a voltage divider setup

I used the exact setup recently to talk TTL with a seagate hard drive that died.. recovered it a charm
Ive tested Echo using putty at 8192 baud, works fine. I can also see a ton of data (illegible) from the PCM whilst connected in putty

Ive grabbed tuner pro RT, and the appropriate ADX files for both my VT and my wifes VY,

Turner pro tests the cable and reports its okay, when i start aquasition it connects and then everything in tuner pro goes nuts.. IE on my VT it thinks im doing 88 KMH with an engine RPM of 63 (while stationary) yet no data errors

Same on my wife's car (that wont start, trying to get the code) it sets and clears DTC's at random in Turner Pro.

Ive tried a few different ADX files and ive even loaded the ADF and Bin files to see if that makes any difference.

Ive tried changing the echo setting and even tried throwing in "Wait for silence" but i dont seem to be getting anywhere.

Any suggestions?

forgot the logfile

Ive also checked the FTDI chip supports 8192 baud by sending data from the arduino at 8192 board to the ftdi chip.. Setting the FTDI to 8192 lets me see the data, 9600 corrupts it.

I've also found a user thats using the same setup over on the turner pro forums sucsessfully
http://tunerpro.net/forum/viewtopic.php ... 53be3540d6


This is the data putty sees from the car at 8192 baud.

ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áHUYû U¡X
ø]ÿP@÷¸W" ¯¹Xí@XF8æAh<<pø7 U!_ <áU£¸W" ¯¹Xí@XF8æAh<<pø7¨U U!_ <áH ¡X

You normally need to add a couple of components to get it to work, there is an example of a basic ALDL interface here .. http://www.techedge.com.au/vehicle/aldl8192/8192hw.htm
NOTE: D3 should be revered.

hmm, looks like i might need to throw a diode and 1k resistor in to clean things up.
Guessing its some sort of back chatter due to the Tx/Rx ports being bridged.

Also found this, were they use two (not sure way) diodes to try and cleanup the signal.. (bottom right corner)
Maybe the sensor voltage on the TTL input is enough for the ECU to think the line goes high?
http://www.mindspring.com/~amattei/aldlif.jpg

ill have a play and post results.

also, we fixed my wifes car, had a mate with a Tech2 imitation drop by.. DFI module connector was loose.

from what Ive seen you will require the diode and resistor between the tx and rx pins. I have made interfaces from little ftdi chip based boards but did require those 2 components to get something that works.

No sucsess with my current setup.. using the diode to try and cleanup RX with a resistor to try and stop the TX from being pulled high for no reason...
Little more experimentation required.

Also.. am I to expect a clean output (as in text) in putty, or is garbage normal?

No you wont get any text, it'll be raw data. you'll either need to real up on the aldl protocol, or need to use tunerpro with the right adx loaded to understand it. Having said that, I tried to make sense of what you posted above and it still didnt look like valid ALDL.

Ohh shiny new Theme.
Anyway

antus wrote:from what Ive seen you will require the diode and resistor between the tx and rx pins. I have made interfaces from little ftdi chip based boards but did require those 2 components to get something that works.

I dont suppose you have a diagram from one of your FTDI designs??
I tried using diode to filter the RX but that just gave me more corrupted data (tuner pro at least realises this is corrupt)

Ok, this was actually a max232, and its dodgy as it was just a simple test on my bench. It did not work without those 2 components.