Gremlins in new build

DIY Builds
#1

I swear my new build is haunted. It’s been having all sorts of issues that seem unrelated. It initially had a unity and a VX2 pro on the last unity firmware.

  • Issue 1: The VX2 would show 0 bars intermittently if I raised it up to look at the screen, but would instantly show three bars if i lowered it to my side.
  • Issue 2: The motors would also cut out for a tiny bit while riding normally and then come back almost immediately. I initially thought that this was related to the first issue, but the cutouts were happening with the remote at my side.

So I upgraded to Vesc 5.10 firmware to see if that would clear the issue and to use the new stormcore app. The upgrade process took its sweet time, but completed without issue. I ran motor detection again and checked the settings to make sure that nothing had been reset in the upgrade. I noticed another issue at this point.

  • Issue 3: My android phone would intermittently disconnect from the Unity bluetooth module despite being 5 feet away from it

During these runs I was also testing the new stormcore app from @sofu on my iPhone.

  • Issue 4: Stormcore app would recognize the Unity bluetooth module, connect to it and function, but would stop recording shortly after starting. I set the location permission to “always allow” before the first test and this happened anyway. It would also disconnect from the board if I was in the app for more than a minute. I don’t think these issues are related to the app itself, I think they merely illustrate issues with the bluetooth module.

After a few test rides with the new firmware, issues 1 & 2 were still occurring. So I ordered a VX1 PPM to replace the VX2 pro. During the install, I also added a Metr.Pro (with long range antenna). After the install, I used VESC tool mobile to configure the PPM settings.

  • Issue 5: The VX1 PPM output was all over the place. With the throttle at rest it would swing between 1.07 and 1.32 ms. My other VX1 (also on a unity) only swung between 1.50 and 1.51. I had to set the throttle deadzone to 20% to prevent the motors from stuttering.

  • Issue 5.1: During the only test ride with the VX1, the throttle seemed very unstable and would vary by up to about 10% faster or slower.

  • Issue 6: The Metr.Pro would also not stay connected. I started a recording during my only ride after the VX1 upgrade and it only recorded for ~45 seconds before it too lost connection.

At this point I think it has to be the Unity that’s having issues because that’s the only common factor among all of these issues.

Does the hive mind have any great insight into what may be causing these problems?

#2

I’ve had these exact symptoms from a connected GND, a connected +5V, and a broken signal wire on the PWM cable that was almost connected, sometimes touching, but broken wire.

#3

Yeah we’ve been seeing these kinds of issues with the Unity BT module. Perfectly fine on Metr or Stormcore or other kinds of nrf52 modules but the Unity module seems to be having issues

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#4

Built in Unity module is more out of touch than our dear leader. (It’s known to drop out)

Also the symptoms really sound like a cabling issue. Probably a bad wire somewhere. I suggest placing everything on a table and turning it on. With access to internal components. Then physically moving various components /wires to see if one of them is intermittently connecting/disconnecting

#5

That’s an interesting theory, but the Unity stayed on during the time of the cutouts in the other components (VX2, Unity bluetooth, Metr.Pro), and they all draw power directly from the Unity. Maybe the internal 5V rail is screwed up somehow?

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#6

Not necessarily a power issue. Could be signal line too.
But the fact that it’s so intermittent makes a strong case for a mechanical issue that you’re trying to pattern match to something that’s really just physical movement on your end.

Maybe.

And by mechanical I mean an electrical signal with a mechanical disconnected / bad solder / bad crimp/ break under insulation etc.

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#7

I’ll try connecting to the Metr.Pro (regular, non-unity) next test to see if that affects the results.

Do you know when the Stormcore 60D will be available? I’m thinking if the Unity is bad I will need a replacement ESC.

#8

Very very soon

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