[tuxit09]

From the wiki - hardware requirement it's understood that we are looking for a 0v-5v square wave.

My sensor from s 98 BMW 328i m52 engine gives a clean waveform but peak voltage is only 0.75v. Part number 12141709616. as such not expecting this to work since the Arduino I'm guessing has a digital high condition of greater than 2.5v input.

Anyone using this sensor? Anyone had to amplify the signal on RPM input? Or advice for getting this right?

[theonewithin]

Isn't that a VR sensor???

Will never work. Need a VR conditioner.

Read the inputs section of the wiki.


https://speeduino.com/wiki/index.php/Ha ... quirements

[tuxit09]

Isn't that a VR sensor???

https://speeduino.com/wiki/index.php/Ha ... quirements

No, it's one of the very few implementation of a Hall sensor that BMW used.

I specifically did mention I read and understand the requirements listed at the link you gave.

I do understand fully the differences between variable reluctance and hall effect sensors. A VR sensor has no square components as shown in the captured waveform.

If you or anyone have a waveform you would like to share that you actually captured yourself and the part number of sensor used I would be very interested in seeing that.

My main question revolves around the lack of amplitude in my signal.

[tuxit09]

Just dug into description and operations sourced from ALLDATA for a 98 328i the following:

"A Hall sensor is used for the crankshaft position sensor input signal on the MS41.1 system. The RPM/reference sensor is mounted on the left side at the rear of the cylinder block. The trigger wheel is now mounted inside the crankcase, on the crankshaft, at the rear main bearing support. The trigger wheel still contains 58 teeth with a gap of two missing teeth.

The hall sensor is supplied with 5 volts from the control module. A digital square wave signal is produced by the sensor as the teeth of the trigger wheel pass by. This type of signal can be directly processed by the control module as a measure of engine speed and crankshaft position.

The signal from the sensor is also used as an input for misfire detection. As part of the 1996 OBD II emission requirements, the engine control module must be able to detect a misfiring cylinder from either electrical or mechanical faults. "

[theonewithin]

I'm gonna call faulty sensor...

It's not really producing a proper square wave.

The troughs are not square at all.

Unless that is expected behaviour of the sensor? Which I don't feel is likely.
Have a spare you can compare with?

[tuxit09]

I'm gonna call faulty sensor...

It's not really producing a proper square wave.

The troughs are not square at all.

Unless that is expected behaviour of the sensor? Which I don't feel is likely.
Have a spare you can compare with?

theonewithin thanks for sticking in there!

Your last post pointed out a couple concerns I did have too but didn't fully grip untill you had me reconsider. Then I believe the answer came to me.

I did realize that it was not a true square. The square component had me convinced the sensor was working. But the weak output didn't make sense. I then thought about what was missing. The high amplitude component which would be the missing square, and boom, pull up resistor hit my in the head.

I checked the RPM1 input open circuit and no bias voltage was found. I supplied a 1K pull-up. ( possible in the mega2560? ).

Then retested best I could waving a screw driver above the sensor produced a super square with no concerns at this time. (Not at shop)

thanks again!

UPDATED: Regretfully.
FROM: https://speeduino.com/wiki/index.php/Sp ... guage/v0.3
*JP4 - 10k pullup resistor for RPM1 input. Should be jumpered ('On') when a sensor is used that switches between ground and floating (Which is most hall effect sensors)