Calibration for Hella APP with (linear, PWM) output

[GregAbles]

Good morning everyone!

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Question:

Will someone kindly explain to me what settings I need to change in order to correlate the Check Signal to the Main Signal in this sensor?

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Background:

I had it wired to the EMU PRO like this:

Hella Accelerator Pedal	EMUPRO8 Header	Vehicle Wiring
A:1, Sensor power (+5v)	C:27, +5V Source B
A:2, Analog signal (linear)	C:19, Analog 4
A:3, Analog Sensor ground (linear)	C:29, Analog GND
A:4, Digital sensor ground (PWM)		Chassis ground, OEM location
A:5, Digital signal (PWM)	A:14, Digital 4
A:6, Sensor power (+12V)		Fuse block, OEM location

Initially, everything seemed to be okay for the linear calibration using the wizard in the software.

However, I kept getting errors about the signal being under voltage, over voltage and the %change being out of range after I manually added the Check Signal parameters.

So, I removed the pedal from the vehicle and connected it with a benchtop power supply and scope.

Most of what I found regarding the voltage ranges, the frequency, etcetera remained the same.

The signal values obtained on the bench are as follows:

	Analog Signal	Digital Signal
Minimum:	0.390 +V	7% DC (200 Hz)
Maximum:	3.60 +V	70% DC (200 Hz)
Behavior:	Voltage increases with throttle application	Positive DC increases with throttle application

Here is a screen capture of the oscilloscope trace with force applied to the pedal (sweep: 0-25%, force: light):

Here is how it is currently configured in the EMUPro:

Note: Some of those values for minimum and maximum may be slightly off because I didn’t initially understand the hysteresis of the signal correlation. Changing those values had no effect that I could tell (or none related to my problem / observation set for this post anyway).

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Conclusion on the intended behavior of this pedal:

As force to the pedal is applied, the Positive Duty Cycle and the Linear Voltage increase.

As force is held constant, the Positive DC remains steady and the linear voltage stabilizes.

When force is withdrawn from the pedal, the Positive Duty Cycle and the Linear Voltage decrease.

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Closing:

Other than correlating this signal, what is the purpose of the “Valid Frequency → Range” variable? That one completely escapes my intuition.

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I thank you for taking the time to look. I also really like this product line. I can’t wait to get this thing running and show it off!!!

[GregAbles]

After making my post this morning, I sat down with a sheet of paper and really tried to wrap my mind around the issue at hand.

I went back through the scope buffer that I recorded and made a table of the Positive Duty Cycle values and the average voltage levels between the rulers.

To whomever may come looking for this information later, let me make a few suggestions before I provide the solution:

1. Data is your friend.

   • I would never have found the answer without collecting the actual information I needed to make this calibration. That is because the behavior is not obvious.

2. Do not “phone it in.”

   • I pulled the pedal off of the vehicle yesterday when I realized that it would be best for me to verify the pedal behavior independent of the wiring and the EMU. Eliminating the possibility of a wiring fault or voltage issue in the vehicle helped me validate the behavior.

3. Take a freaking break and come back to it. I did not but I am about to. This has been a rigorous test of my skills, patience and resolve.

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So, the answer was pretty simple. The values I gave in the first post are all inverted. This goes back to point #2 above. By taking the pedal out and getting situated where I could properly control the input and output of the pedal, I was able to obtain much better information. One of the ways I did that was setting up multiple measurement scenarios in the Pico software.

While I was looking for (and recording) “Positive Duty Cycle” values - the EMUPro was looking for “Negative Duty Cycle” values. So, when I took another look at the EMU Client and noticed that my Duty Cycle actual value was 92.3 - It immediately clicked. It took a minute but I got it and hopefully you will too now.

I am still getting errors in three of my bins. But like I said, I am now taking a break - even though I really need to keep going. Gotta let these well-done brain cells cycle, lol.