(Almost) free DIY ADS interface

[dataxpress]

Ok guys this is great! We're all but done. Something simply isn't asserting the bus to something else's liking.

There are now only two possibilities. Either the vehicle isn't pulling low enough for the 4053's input or the 4053 isn't pulling low enough for the vehicle.

It is very easy to test either possibility, but I'd like to start with the latter as I believe it is most likely the problem. All we need to do is add a pair of discrete transistors to the 4053 design between the 4053 and the buses. This should hopefully allow the 4053 interface to work just as the original one does. If so, then we'll have determined the exact cause of the problem. I'll make a minor modification to HansV's circuit and attach the modified schematic in my next post.

Two npn transistors (exactly the same kind as the other two in the circuit) must be added - one per bus. The outputs of the 4053's switch A (pins 12 and 13) must then be disconnected from the buses and connected instead to the bases of the transistors. Each transistor's collector then goes to the appropriate bus, and the emitters go to ground. The input for the 4053's switch B (pin 10) must remain where it is on the k bus.

Now the 4053 does not drive the buses directly but instead drives the additional transistors which then drive the bus. However, adding these transistors has inverted the logic so we must invert it again elsewhere to compensate. As it happens, we can accomplish both this and one more thing by disconnecting the ground connection from the emitter of T1. This will prevent T1 from inverting the signal by turning it from a transistor in to a simple diode, which is fortunate, because this is exactly what we needed to protect the 4053 from any negative voltages which might now come through the TXD pin of the serial port toward the 4053.

Stand by for the modified schematic. I have given the written description of the modifications only in case it is needed to accompany the schematic. It's actually a very simple change to make, despite how clumsy the written description may have been.

I'm fairly confident that this test will conclude our troubleshooting efforts.

Awesome. I don't have an adapter built with a 4053 handy, so KevinMullins will have to test out this change.

Pretty exciting to have all this nonetheless!
Now time to get DIS working again...

[benemorius]

I've now attached the modified schematic to my last post. If it can't conveniently be tested by anyone right now that's ok. We can still have a high degree of confidence that we've correctly identified the problem.

[KevinMullins]

It might be worthwhile to try to draw a truth table about both circuits and see if anything doesn't match up. Sounds like this is what you're trying to do in your head, anyway.

Dang, I screwed up and lost my entire post while trying to edit it, gonna throw it here with some added notes I was trying to squeeze in there.

I keep going back to this for some reason, especially since it was brought up earlier, hoping someone else could take a look and see if anything jumps out at them when comparing my video and Hans's schematic.
A truth table would probably help me "seeit" as it functions for sure.

In my video I am probing at pin 11 of the CD4053 in Hans's schematic.....
Green is low - Red is High
Looking at the CD4053 diagram: when pin 11 is LOW (green) - pin 14 is connected to the K-Line. Shouldn't this be to the L-Line if wake/queries are done on the L-Line?
When it is HIGH (red) - is when it should be expecting data/response on the K-Line. (?)
Hard for me to wrap my head around it at the moment as I keep getting disturbed, but I keep thinking something is "backwards".

Can I easily invert the inverter on the DTR line and see if it makes a difference?

Switching according to the note on our schematics: But I see something different going on when I look at the schematic itself. (note:CD4053 in the schematic is drawn in the LOW state)

DTR=low: PIN15 (L-line) connected to TXD
PIN 17/20 (K-line) connected to RXD
I see: PIN 17/20 (K-line) connected TXD
PIN15 (L-line) not connected

DTR=high: PIN 17/20(K-line) connected to TXD
RXD connected to ground
I see: PIN15 (L-line) connected to TXD
PIN 17/20 (K-line) connected to "B"

Seems the RXD from the RS-232 is always grounded whether the CD4053 is high or low.
Anyone else see something wonky here or am I just thinking to far into it?

I await benemorius's updated schematic as I'll give that a shot too for sure.

I've now attached the modified schematic to my last post. If it can't conveniently be tested by anyone right now that's ok. We can still have a high degree of confidence that we've correctly identified the problem.

I'll definitely give it a try soon as I get a chance to and report back.

Now the 4053 does not drive the buses directly but instead drives the additional transistors which then drive the bus. However, adding these transistors has inverted the logic so we must invert it again elsewhere to compensate. As it happens, we can accomplish both this and one more thing by disconnecting the ground connection from the emitter of T1. This will prevent T1 from inverting the signal by turning it from a transistor in to a simple diode, which is fortunate, because this is exactly what we needed to protect the 4053 from any negative voltages which might now come through the TXD pin of the serial port toward the 4053.

So could T1 be replaced completely with something like a 1N4001 diode?
And if so, what would the proper orientation be? (cathode towards CD4053?)

[benemorius]

So could T1 be replaced completely with something like a 1N4001 diode?
And if so, what would the proper orientation be? (cathode towards CD4053?)

It could indeed, and yes the cathode would connect to the 4053.

[benemorius]

I'm attaching some colored schematics in the hope that it will shed some light on the workings of the circuit. I don't see any problems with the logic and I don't believe there are any.

There are two images. In one, DTR is low. In the other, DTR is high.

I have colored RED the parts of the circuit which are HIGH, and have colored BLUE the parts of the circuit which are LOW. In other words, if you measured a red part of the circuit with a voltmeter it would be close to 12 volts and if you measured a blue part you would find it near 0 volts.

Near each of the three switches in the 4053 I have used an arrow to indicate which position the switch is in based on whether its input is high or low.

I have drawn serial TXD as well as the K and L buses in their idle state in both images. The only change between the two images is the state of DTR coming out of the serial port and the subsequent changes that occur as a result.

[KevinMullins]

Cool. I look forward to examining those, ought to help eliminate some of my own confusions I tend to add into the equation.

Probably won't get much done this evening, but I certainly will shortly.

[KevinMullins]

Update -
Tried the changes with two added transistors and replaced T1 with a 1N4001 diode.... No communication whatsoever. Could not read a single module including the ones we were getting before. Neither INPA or DIS could access anything. Even tried a second pc.

EDIT: I may need to double check my entire interface circuit, I put it back to original and it's still not working, even as limited as it was originally. So I'll play with it some more and post back.
EDIT #2: The CD4053 had died, not sure why though. I have it working again as it was prior to the added transistors.

[benemorius]

Update -
Tried the changes with two added transistors and replaced T1 with a 1N4001 diode.... No communication whatsoever. Could not read a single module including the ones we were getting before. Neither INPA or DIS could access anything. Even tried a second pc.

EDIT: I may need to double check my entire interface circuit, I put it back to original and it's still not working, even as limited as it was originally. So I'll play with it some more and post back.
EDIT #2: The CD4053 had died, not sure why though. I have it working again as it was prior to the added transistors.

It's possible I've done something foolish with the schematic, but I don't immediately see what it would be. Is it possible that anything was wired up incorrectly? Did you leave R1 in place when you replaced T1 with the diode?

[KevinMullins]

I literally tripled checked my circuit against the schematic prior to testing it.
And yes, I left R1 in place and just put the diode in place of the transistor accordingly.

The CD4053 was internally shorted between pin 1 and 16...which in circuit would be a dead short to ground. Not sure if the changes had anything to do with it or if it was just a fluke. I have a few spare, I may try it again just to confirm.

[Micronaut]

Hi to everyone! I'd like to say great Thank's to benemorius and everybody, who help to develop this project.
I've built this device on a veroboard and it seems to work fine within INPA 4.4.7 + EDIABAS 6.4.3 on my BMW 520i e34 m50b20 1991'year with Siemens MS40.0 DME onboard. I tryed INPA 5.0.2 and it's also seems to be fine also =)

I'll make a report with the photos later.

But I have some doubts now, whether my INPA's settings are correct. So, I pressed <Shift+F5> in main INPA window and chose E34 -> Engine -> MS40.1 - because there are no MS40.0
Is it correct?? I'll be so thankful for any clearence of this question..

P.S.: Sorry for my English, i didn't practice for a tonn of time =/

[Micronaut]

pheno, thank's for your kind assistance!
I'm just installing DIS, but I'll need some more time to learn how it works.
I built an original benemoruis scheme as I had a KPS2222A and KPS2907A transistors on my job.

[benemorius]

Hey guys. Sorry for taking so long to reply, but I bring updates and good news!

@KevinMullins
You should try the modified 4053 circuit again. I built one and it works.

... If it can't conveniently be tested by anyone right now that's ok. We can still have a high degree of confidence that we've correctly identified the problem.

I couldn't resist the need to know, so I decided to test this myself. I built the 4053 circuit and was able to try it on my car today.

I can now say with certainty that the problem was exactly what we had narrowed it down to - the internal resistance of the cd4053 is too high and it is not pulling the bus sufficiently low.

With the unmodified 4053 circuit in place, the L bus was only going down to 5.15V from 12.6V. Not surprisingly, this is not low enough and thus the DME does not respond.

After making the modifications I posted, the L bus is asserted nearly all the way to 0V and communication with the DME is successful.

Therefore, anyone building a circuit from this thread is advised to build either the modified 4053 circuit or the original circuit in the first post.

[KevinMullins]

Good news indeed!!

@KevinMullins
You should try the modified 4053 circuit again. I built one and it works.

I'll give the modified version another go, not sure why my CD4053 died the first time around.
I'll even try another from scratch and see how it goes.

Did you use a diode in place of T1 or did you just lift the leg of the transistor?

Did you use the BC547's or something like 2n3904's for the NPN transistors?

And are you using the standard INPA files for the DME? (un-modified 3.3.1 files)
Seems some have had trouble connecting to non-EWS DME's with various other interfaces.

[benemorius]

Good news indeed!!



I'll give the modified version another go, not sure why my CD4053 died the first time around.
I'll even try another from scratch and see how it goes.

Did you use a diode in place of T1 or did you just lift the leg of the transistor?

Did you use the BC547's or something like 2n3904's for the NPN transistors?

And are you using the standard INPA files for the DME? (un-modified 3.3.1 files)
Seems some have had trouble connecting to non-EWS DME's with various other interfaces.

I left T1 and just lifted the emitter. The transistors are all 2n3904.

I'm not too sure about INPA files since I set it up so long ago. I don't recall doing anything extra to set it up and my DME331.IPO was last modified in 1997 so I'd wager everything is standard.

This is offtopic, but is there a source of information somewhere about the actual modification of these files?

I've often toyed with the idea of writing some modern software to completely replace INPA/DIS in order to get away from the ancient laptop syndrome. The best way to do that would of course be if the software could parse the IPO files itself, but I don't know how to do that yet so it would be great if someone else already does.

[KevinMullins]

I left T1 and just lifted the emitter. The transistors are all 2n3904.

Cool. I keep that in mind when I do mine again.

I'm not too sure about INPA files since I set it up so long ago. I don't recall doing anything extra to set it up and my DME331.IPO was last modified in 1997 so I'd wager everything is standard.

If your file date is 1997 then it is an original file.
There is a 1997, a 2004, and a few "modified" non-EWS versions of 2012 floating around.

This is offtopic, but is there a source of information somewhere about the actual modification of these files?

Member "FAL" is probably the one to talk to about all that.

A couple threads that may be of interest to ya -
http://forums.bimmerforums.com/forum....php?t=1845181
http://www.bimmerforums.co.uk/forum/...hanks-t105302/

[dataxpress]

Member "FAL" is probably the one to talk to about all that.

A couple threads that may be of interest to ya -
http://forums.bimmerforums.com/forum....php?t=1845181
http://www.bimmerforums.co.uk/forum/...hanks-t105302/

FAL definitely has done it, though I think he had mentioned having access to special BMW software to deal with encryption on these files? Not sure if by "encryption" he just meant "encoding."

I haven't done a lot of format decoding before, but I think that TOOL32 will provide a lot of insight here. If you do start the project of trying to decode the format & writing an INPA/DIS replacement, I'd love to be in on that.

[v2x]

@dataexpress:

can you help me (and other electrician beginners) with your breadboard circuit? It would be very nice of you.

1.your pic is good (maybe you can make another pic/s ) so we can see which cable goes to connector.

2.please make a part list of your used parts

3.in the background of your pic (post #190) which circuit is that?
( can you post the link? )

hope you can help me an maybe others

greeting

[KevinMullins]

3.in the background of your pic (post #190) which circuit is that?
( can you post the link? )

That is the original design by benemorius from post #1 which also includes a parts list.
http://forums.bimmerforums.com/forum...68&postcount=1

[v2x]

hi,thanks i overlooked that :-(

in the graphic: all the "12v points" i must connect wit pin 14 from the 20pin-adapter,right?
and all the "GND points" connect to pin 19 from the 20pin-adapter,right?
thats all?i will be very happy when it is so easy to get a ads interface

ok this ads circuit works and is tested?"my car is 1995 e36"
works with inpa and i can see also the live datas?
inpa i install in ads mode for this,right?
will it work with dis?
greeting

[KevinMullins]

in the graphic: all the "12v points" i must connect wit pin 14 from the 20pin-adapter,right? YES pin 14 is a constant 12v coming from the car.
and all the "GND points" connect to pin 19 from the 20pin-adapter,right? YES that is the ground point coming from the car
thats all? Yup, all ground points tie together, all 12v power points tie together.
ok this ads circuit works and is tested?"my car is 1995 e36" So far there has been good luck with this particular design on all the older E36's
works with inpa and i can see also the live datas? Yes, but I can't tell you exactly what all will work on your particular modules per model year, etc.
inpa i install in ads mode for this,right? Yes, use ADS mode for the older cars. 96' or newer has some OBD functionality, but should still use ADS as well.
will it work with dis? Anything that works with INPA should work with DIS. It is always recommended to get INPA working properly before even trying to mess with DIS.

[v2x]

hi,thanks for your answer.You also use this or similar interface?
Tomorrow I'll try to raise the components,with a little luck the store has what I need.
i have a orig. bmw service-rester,of this I will take the 20 pin connector.
pin 5 of the DB9 connector is also on the vehicle mass (Pin19 of 20pin) right?

so now everyone should understand that.
many thanks,I'll post the results
greeting

[KevinMullins]

hi,thanks for your answer.You also use this or similar interface?

I've used a couple different ones and have been working on/with a version of this one as well.

pin 5 of the DB9 connector is also on the vehicle mass (Pin19 of 20pin) right?

Yes, that is correct.

[KevinMullins]

V2x, you may want to take a look also at the one with CD4053. It's more simple. The modified schematic picture is in post #202.

We could definitely use some more testers on that modified version.

However I'm not sure what the red circle with X inside it means.

That particular leg (emitter) of that transistor gets lifted / removed.
I plan to try this design again with a diode in place of that transistor.

[v2x]

hi,,more simple?i think for the first one the other schematic is better for me ;-)
also i don´t know how to program the cd4053(i read about) and how it works,which pins ect.and i found many different cd4053.how long it takes that until I can post links or photos???
i wanted post some pictures if my interface is ready , but I can not.
is her also no pm-function(privat-message)?
greeting

[KevinMullins]

The CD4053 does not require any kind of programming. It's basically three transistors rolled into one chip.

You need 10 or 15 posts I believe before you can post pics or pm.