[rallikuski]

Hello!
It is possible now connect VSS signal to RPM2 input trought vr conditioner at 202402 firmware?
So how to wire RPM2 input?
I have 12v square wave signal from speedo.
I allready tried to put that signal to RPM2 input and changed VSS input pin from "board default" to "pin18" from tunerstudio and there is nothing happening...
Do i need to wire RPM2 negative fron conditioner to earth too? I tried that too and nothing happened

Sorry foor noob questions

[sparkness]

you will need to have the pull up resistor in place if using a 3 wire hall effect type sensor

[PSIG]

I would suggest using an aux input for this, as the code may not react well to pin 18 input. To route a 12V hall signal to a Mega pin, use a diode inline to block high-voltage, only allow grounding by the sensor, and a 5V pullup on the board to create a functional and safe 5V-0V square-wave signal to the processor. A level-shifter. This method has been used on many projects:

SENSOR SIGNAL > DIODE (cathode toward sensor) > 5V pullup > Mega

[rallikuski]

I would suggest using an aux input for this, as the code may not react well to pin 18 input. To route a 12V hall signal to a Mega pin, use a diode inline to block high-voltage, only allow grounding by the sensor, and a 5V pullup on the board to create a functional and safe 5V-0V square-wave signal to the processor. A level-shifter. This method has been used on many projects:

SENSOR SIGNAL > DIODE (cathode toward sensor) > 5V pullup > Mega

Had some free time with mercedes and I did modify VSS inpput to arduino pin20 (default) and added diode and pullup like at that pic but its not working
Is that pullup resistor too high value now? Its now 4.7kohm...
Need to study more and try something else with that VSS input. It would be nivce to get that work.

First time when I tested that VSS input I just made simple voltage divider setup with basic resistors between ground and 12v VSS signal and I had even something bouncing speed signal at speeduino. Now just nothing
When I tried that VSS input was arduino pin20 (default).

[PSIG]

This is why we need to know exactly what signal comes from the sensor. Verify the raw signal from the sensor. Is it high-low, or GND-float, or what, exactly?

If the sensor does not ground (alternating with float or V+), the circuit above will not work. That's unusual, but could be your case. If true, then a safer circuit is to replace the diode with a Zener diode to ground, such as the voltage regulator circuit here.



For that circuit to protect the processor, and as system voltages can exceed 16V; the resistor could be 470-ohm ½W, and the Zener 4.7V ½W. The BZX79C4V7 or similar diode from 4.7 to 5.1V should work well.

[rallikuski]

This is why we need to know exactly what signal comes from the sensor. Verify the raw signal from the sensor. Is it high-low, or GND-float, or what, exactly?

If the sensor does not ground (alternating with float or V+), the circuit above will not work. That's unusual, but could be your case. If true, then a safer circuit is to replace the diode with a Zener diode to ground, such as the voltage regulator circuit here.



For that circuit to protect the processor, and as system voltages can exceed 16V; the resistor could be 470-ohm ½W, and the Zener 4.7V ½W. The BZX79C4V7 or similar diode from 4.7 to 5.1V should work well.

I was thinking this same setup to test. Need to take time and buy some parts for testing.
I dont have oscilloscope to check that signal I found from many place at mercedes forums that signal in 0-12v square signal but not 99% sure for that.
I know Im little bit "noob" with electrics but nothing is not broke yet and car is running good without VSS too.

But I have to thanks all of you who helped me again with my stupid questions

[PSIG]

There are many circuits to accomplish signal inputs, and these are just a couple. Others here may have simpler, better or other suggestions, and they are welcome.