Laurence Gibbs

Ok so I dug out the interface I made and tested it on hyperterminal. I get a nice echo back and the green light flickers each time i hit a key. The design is the Andy Whittaker one. Are there any other tests I can do to make sure the interface is ok before i hook it up to the port on the car???
If I connect the software up to the board both lights (red and green leds) pulse on and off in time with the connect message on the software screen, is that what it does when not connected to the car???
Hope someone who has a working interface can give me a few pointers.

Laurence Gibbs

Small update. Connected to the car. With ignition on both lights pulse on and off and also the green light flickers as if it's recieving something but i get nothing from the software? if the interface is just pluged into the pc and a 12v source both lights (red & green) just pulse on and off there is not the secondary pulsing that happens when connected to the car?

Laurence Gibbs

anyone who has tried to pm me please try again as my email has now changed. Thanks

LeRoux Strydom

Which line have you connected up on the 19-pin plug? Tell us when you have it figured out. I am waiting for Andy Whittaker's opto-isolator circuit board to arrive to try this out myself. Are you using Doug Boyce's software?

Laurence Gibbs

Yes it's his software. Not figured it out yet. It does all the things in the previous two posts but does not "connect" I have a nice flashing green led on the interface board which looks as if the car is sending something. There is some problem with the DTR line according to pncarrerars but i've not figured it yet. I am also going to try Greggs design to see if that works instead. I am going to have another crack at it tommorow. I will try connecting a rs 232 break out box to monitor what's going on. I ran a Port monitor test on it and it fails on the read cycle, it timesout.
Gregg's design does not have dtr connected, only four lines are used tx rx rts gnd. The Andy Whittaker design has dtr connected via a resistor and there are links to set either recieve permantly on or recieve set by rts ? if I set recieve perm on i can get an echo with hyperterminal but Doug's software works differently!

DougB

Hi Laurence,

The blinking you see indicates the 5 baud wake up signal being sent on the L line. The wake up starts as soon as you start the software and repeats until the ECU in the car responds. You should see a 2 byte response from the car on the K line. These 2 bytes should appear on the rx line if everthing is working.

At first glance, Andy's interface would appear to work but you would have to change the jumper so that it operates in "rcv always" mode. The software expects that the tx and rx lines are connected so ever character it sends is echoed back.

-doug

Laurence Gibbs

Hi Doug,
thanks for replying. I think I am getting a response from the car to the interface the leds flash the wake up and then the green led flashes something back. I dont get the additional flash back if the cars not connected to the interface. The jumper is set to "always On" . I will see what the break out box and a scope will do for confirmation. Pete "pncarrerars" tells me he had a similar problem which was due to the way dtr is handled and you had a modded version of the software that solved this. My board echos back using hyperterminal but not with the software. Could this be my problem?

garrett376

I'm lost (and curious) - what is it you guys are doing, trying to read the codes from the DME memory using a personal computer?

MA7008O

So am I, VERY INTERESTED!!!!!!!!!!!!!!

pncarrerars

Hi Laurence,

Although I have Dougs software working with my interface this has reminded me that I always intended to get it working with another one so that I had a spare. I have ordered one from Andy Whittaker & will let you know how I get on.

Pete '92 964 RS

Laurence Gibbs

Garrett et all, yes using an interface (readily available on the net) and some software kindly supplied by Doug to read the fault memory among other things . Pete will be very curious how you get on. At my current speed / luck you'll probably get it working before i do lol. Right back into the garage with the scope this time!!!

Laurence Gibbs

Update. My scope does not have single shot (been about ten years since i used it) so i cant see distinct signals but can see "switching" I used the breakout box instead and can see the different way the dtr line is handled between hyperterminal and Dougs software. I also used the logic analyiser that i have on my multimeter, I get a distinct high low from tx, the K line goes high and "off" rather than a full logic 0 but that might be my analyliser not being quick enough. Recieve on the breakout box shows nothing. Unlike in hyperterm.
Pete any chance you could send me your modded software to try?

pncarrerars

Hi Laurence,

Whilst you have been testing & I have been waiting for delivery from Andy Whittaker I have been searching the web a bit & there seem to be a few cases of people having to fine tune a resistor value in the K line circuit. If the K line goes "high" and "off" rather than low it may not drive the PC recieve properly. If this is the problem then I might expect echo with hyperterminal to work with the K line disconnected from the car but to stop working if the K line is connected.

Please excuse my thoughts if they appear a load of b******s as my background is software not electronics.

Pete

Laurence Gibbs

I suppose it would be more correct of me to say indetermined state rather than "off" but i think u get the idea. It does seem like it could be something straight forward like to much loading from the wrong value resistor. My background is electronics but I went out of that sphere of engineering 15 years ago. I should be be able to work the diagram out easily but have to admit the grey matter aint what it used to be.

Lorenfb

You're probably using Rennlist posted interface which is very very simple.
You need to check that the RS232 levels (~= +/-12) are correct,
and the DME levels (0/12) using an o-scope.

Note: The T1-IN probably should have a CMOS buffer from the K-Line
for proper level translation.