Nochmal Thema VAGCOM-Adapter | Posts 16+

christians wrote:

The IC doesn't need a lot of "accessories." Therefore, it would require fewer rather than more parts.

Hi Christian,

However, the MC 33199 unfortunately does not offer any conversion between OBD and COM port signals, which means that the components "to the left of the optocouplers" must remain as they are .

Hi Ulf,
To convert the driver's output signals (TTL) to a serial interface, you could use an IC from the MAX232/233 family.

Best regards, Rudi.

I was just on the English-language VAG-Com forum.
The problems I'm having with my AAT BJ92 are (also) related to VAG-Com. U. Ross writes that all "very old" Audi TDI models operate at 240 baud, which needs to be set in the options. I will try this as soon as possible. Ross is having problems with these vehicles because 1. TDI models were only sold in the US starting in 1996, and 2. other protocol parameters also differ.
Christian.

I've now tried 240 baud, but unfortunately without success. Similarly, using our oscilloscope didn't work; it can't store the waveforms, and I lack the experience to interpret everything I see. Also, the battery ran out, so I had to postpone the experiment. So far, I've only observed that the voltage levels fluctuate between a maximum value and near zero even on the live object, which my slow multimeter can't display. It was also clear that the engine control unit responds at a much lower frequency than the ABS system.
Christian.

christians wrote:

It was also clear that the engine control unit responded at a much lower frequency than the ABS.

Hi Christian,

That would actually align with the statements made by Ross, so perhaps the adapter isn't to blame in this case.

Hi Ulf,

That's also my concern. After all, I can modify certain parameters within the software without interrupting communication with the ABS. Since I currently only have the shareware version, I don't know what happens when data blocks are received.
Unfortunately, U. Ross is also very secretive about details regarding protocols and baud rates. Presumably because this data, obtained through reverse engineering, represents his true asset.
I'm also going to try using the microphone input of the sound card with appropriate software as a storage oscilloscope. However, it probably won't work perfectly because the inputs are typically connected capacitively, which means you can't measure DC voltage levels. Let's see how a switching event will be displayed with this setup...

Best regards, Christian.

christians wrote:

I will also try to use the microphone input of the sound card with appropriate software as a storage oscilloscope. However, this will not function perfectly because the inputs are usually connected capacitively, so you cannot measure DC voltage levels at all. Let's see how a switching process is displayed with it...

Hi Chris,

As long as the lower cutoff frequency of the input is sufficiently low (20 Hz or less), a usable representation should be possible.

While the "roofs and cellar floors" of the rectangles will slope more or less diagonally towards the zero line (like with an oscilloscope using AC coupling), this only happens with relatively long, slow pulses.

HI.

I've finally found the problem after numerous successful dry runs. I had to remove resistor R15, which interrupts the ground connection. Since then, there have been no more issues, and the potentiometer position doesn't matter anymore.
'Now I'm having problems with the German VAG-COM version DRV 208.2; it's not very stable and crashes quite often.'

Niemand wrote:

I have finally found the error after numerous successful dry runs. I had to remove resistor R 15, which interrupted the ground connection. Since then, there have been no more problems, and the potentiometer position is irrelevant.

Hi.

Interesting... I thought that 100 ohms couldn't cause any interference.

What kind of computer/laptop do you use? Does it run directly off the onboard power supply?

If the laptop were only powered by its battery, the reason for the behavior of R15 would be even more puzzling...

Quote:

Now I'm having problems with the German VAG-COM version DRV 208.2; it doesn't run very stably and crashes quite often.

Hmm, and which software did you use, as you mentioned above?

Quote:

no more problems

?

Hello Ulf,

I don't understand why you didn't use a 7810 voltage regulator for R19. You could compensate for the voltage fluctuations with it for just a few cents. Have you tried that?

AndyO wrote:

I didn't understand why you didn't use a 7810 voltage regulator for R19. You could compensate for the "floating" around the operating voltage for just a few cents. Have you tried it?

Hi Andy,

Sure, a 7810 or similar would provide stable voltages.

But I want to provide the car's K and L lines with a board voltage that is as close to its maximum level as possible, without significant reduction.
And with the engine running and a battery voltage of approximately 14 volts, you would already be missing about 4 volts after a 7810 regulator .

Hello,

Does anyone have any idea where I could get ahold of an MC33199?
I still can't find anything about that online.

Thank you in advance for the tips.

Best regards.
Sure.

Please provide the text you would like me to translate from German to English. I will only provide the translation, without any explanations.

You can find MC33199 and MC33290 at http://www.segor.de/.

Regards,
Okay, hier ist die Übersetzung:

'Vlad.'