Hall effect Sensor HiHat Not Getting Full Range Anymore

[Stephen Spurlock]

I am having problems with my HiHat that I built. I have a 56 input MegaDrum MCU: STM32F205RCT6 // I have the positional sensing add-on board // FW version: 20181218 // MegaDrumManagerFX Version 20181028 // My MegaDrum is connected by USB to my MacBook Pro.


I am using the Allegro 1302 Hall effect Sensor and setting up an a-to-e conversation hihat. The HiHat seemed to be working for about 2 months, I used the auto function to get a rough estimate by moving the hihat up and down several times, and then I pressed the HiHat all the way down and adjusted the “Low” setting till there wasn’t red showing on the meter in MegaDrumManagerFX. Then I adjusted the “High” setting till the meter was full red on MegaDrumManagerFX. Then one day about a week ago it didn’t have a full range of motion. I wasn’t sure what was going on but when I pressed all the way on the HiHat it would not go all the way down on the meter, and the same for when I released the hihat. I have since been problem solving. I have checked all the connections and even took apart the system and gone back to the bread board. So I have some questions for anyone who is using a hall effect sensor for their hihat.

1st:: I am getting 4.4 volts out of the MegaDrum without the sensor connected. Is that a normal voltage?

3rd:: I am getting 3 volts out of MegaDrum going into the sensor once I connect the sensor (VCC). Is that correct?

4th:: I am getting 1.4 volts out of the sensor (VOUT) when the hihat is all the way open (i.e. the magnet is far from the sensor) Is this a normal voltage?

Magnet Far.png

5th:: When the strong magnet is very close to the magnet I am getting 3.3v on the positive side and 0v on the negative side of the magnet (VOUT) . Is that normal behavior?

Magnet Close.png

6th:: (as a note I have the reverse levels checkbox checked on the Misc settings) I set the Low setting to 1000 and the high to 101 and then click on the “Auto Levels” option and I moved the magnet close to and far from the sensor several times. The auto level suggested that my low be at 361 and the high setting should be at 855. This put my range from 17 to 74 with the meter on MegaDrumManager FX. If I raise the “Low" setting it doesn’t ever go below 17. (if I lower the number it goes up proportionally) If I lower the “high” setting to 697 I can get the range to 85 (If I raise the “High” setting it maxes out at 1023 and the open level goes to 63) Is this a normal range? I was getting a better response in the past but I am not sure what changed. How do I change the setting in MegaDrumManagerFX to get the full range on the hihat?

Best Option.png

7th:: This is an idea I had but if I connected the 4.4 volts wire to what should be connected the VOUT side of the sensor that should just be 4.4 volts sent to MegaDrum and I thought I should be able to at least a fully closed hihat (because my levels are reversed), but I can never get below 17 on the meter in MegaDrumManagerFX. Even if I connect and disconnect the wires with the auto function on I never get a full range on the meter with MegaDrumManagerFX. Shouldn’t connecting wire 40 to wire 39 (the 4.4 voltage wire to the low impedance pedal wire) give a completely closed or open pedal (depending if your levels are reversed)?

I am sorry if there is an obvious (I hope) solution but I am at a lost. Also, I am sorry if this is discussed on a different forum page but I have been looking. My mega drum is working great other than the variable hihat. Anyone’s help would be greatly appreciated.

[dmitri]

1. Power from MegaDrum is provided from internal 5V over a 100 Ohm resistor. Voltage the HiHat power will depend on the load the HiHat controller draws. With nothing connected it should really show 5V, with a load it can be anything depending on the load.
2. If nothing else changed (broke) then you might have changed the HiHat Pedal Curve.

[Stephen Spurlock]

That worked, it was the HiHat Pedal Curve! That was an easy fix that I wish I would have done about 2 week ago! Thank you so much for your help.

As far as the voltage not being 5v, is there a reason that It could be low. If there isn't an easy explanation with MegaDrum I am thinking that it is probably an issue with my cheap analog voltmeter. It probably isn't very accurate. I might pick up another one that is a better quality. But it seems to be working great.

Thanks again!