CAN-Simulator | Posts 16+

So, I went to two VW workshops this morning. At the first one, they didn't take me seriously. They didn't even let me finish explaining. Well, 'Service Desert Germany.' At the second one, I was luckier. There, I was confirmed that the tachometer signal is a square wave signal (I read about the analog signal in a forum). However, they don't know the frequency either. The workshop can probably only measure whether a signal is present or not. What gives me hope again is the statement from the workshop foreman that he is 90% sure that only the engine speed comes in as a CAN signal. Therefore, the speedometer should work. I will install the tachometer in a workshop and have the immobilizer deactivated. I just need to find a workshop that would do that. Because no one wants to take on the job, they say it's too theoretical. Perhaps someone in our region around Ravensburg knows of a suitable workshop?

Greetings TBN.

Hi TBN!
Actually, what you're planning should be relatively straightforward. Put a PIC 18F2480 and an MCP2551 driver on a circuit board, add a 5V voltage regulator, then make a small adjustment with resistors or a potentiometer to feed the analog signal into one of the A/D converter inputs, and that's it. The PIC will sample your analog signal every 100ms (or so) and send out a (suitable) CAN packet.

It would be important to determine the structure of the CAN packet here, specifically which ID should be used, how many data bytes it should contain, and what information needs to be included within those data bytes. Once that is defined, we can develop the software for the PIC microcontroller.

I already have a complete circuit here, but what I'm currently lacking is proper documentation about the commands on the CAN bus. However, it seems like we're stuck with guesswork because this stuff is once again proprietary, 'copyright' protected, and kept strictly secret by the manufacturers, so that no one can build anything worthwhile .

Regards,
Stefan.

Which microcontrollers can be used for this?

The radio only receives the gala signal and uses it for dimming.

If the old car has a K-Line (ISO9141), I wouldn't bother with the (pointless) effort of converting both signals to CAN using an ESP32 Xiao (9141 -> CAN). Technically, it's feasible, even if the car doesn't have a CAN bus; something can be mapped and adapted in that case, 100%, but what's the point of all that work? It would be better to install an original or aftermarket radio. Unless this particular car is (your) absolute dream car (a collector's item), and you absolutely need that specific radio to function in it.