Tronic 250r stuck at WOT

[Barncat]

In the never ending saga to get my Blackcomb bike build with the Tmotor U-15 running properly, I put a Tronic 250r on it. Ran great for about 75 miles (FOC), no top end cutouts as with the Flipsky 75200, just a faint low-mid range shudder that I was trying to tune out.

Yesterday, ADC1 throttle pegged at wide open- fortunately while I was stopped with rear wheel lifted off the road. Seconds before i heard a sort of light metallic clinking, so stopped to investigate.

This is of course the most dangerous condition possible on an ebike (2nd being a battery fire). This controller has on off switch capability, and the button i installed next to throttle worked and shut it off.

In subsequent bench testing, the unit still turns on and off normally- blue, then blue+green led. Throttle functions ok until 1/2 open, then pegs at WOT and stays there- the separate ADC2 regen thumb throttle is still working normally and will kill it, or shut off switch must be used.

Again this was a sudden malfunction- was working normally. 15s battery pack, all parameters set within Tronic specs, ADC1 and 2 set to 3.29v max, all wiring and connections triple checked, Comm port JST plug tight, swapped on a brand new throttle- no change, zero smoke/heat/smells/burned components or obvious issues, further noises or other malfunctions.

Seems to me a board component failure. Opinions?

 

[amberwolf]

Sounds like a firmware issue--bug in the programming. There shouldn't be anything in the input circuit that could do a "sample and hold" type of function other than inside the MCU itself, in the way you are seeing.

If you use a multimeter, does it actually read WOT voltage anywhere from the input to the MCU when it happens? If not, and the actual voltage on the signal trace/path is the real actual throttle voltate, it's definitely in the MCU, either a wierd hardware failure inside it, or more like a software bug.

 

[Barncat]

Hey amberwolf- btw it's a simple 3 wire throttle; just tested at 3.28v red to ground, and .75v sense wire to ground at rest. At WOT malfunction, sense wire to ground is still .75v, so there's something hosed up on the board apparently.........

It has version 5.03 firmware. Just pulled up last year's vesc-tool and ran input wizard detection as a hail mary. Same SNAFU. I don't think it's software, especially since it was working properly for 5 or 6 hours of hard road time. I recall working with a previous controller where if you disconnected i believe the ground wire it would default to WOT, but not the case here.

It's possible but unlikely I've overlooked something. There were really no variables prior to failure as a differential diagnosis. Last idea i have is that it was to do with the metallic noises i heard immediately beforehand. Anyone heard of this before?

 

[amberwolf]

Hey amberwolf- btw it's a simple 3 wire throttle; just tested at 3.28v red to ground, and .75v sense wire to ground at rest. At WOT malfunction, sense wire to ground is still .75v, so there's something hosed up on the board apparently.........

Is that just at the throttle-to-board connection, or is that all the way to the pin on the MCU?

If it's all the way to the MCU still good, then that eliminates anything wrong wiht the board itself other than software (or a really wierd MCU defect).

Software that was working perfectly can "go wrong" when a bit gets trashed in flash memory, which can happen because of a bad memory location, or because of cosmic ray / other hard (particle) radiation.

Since it fails at half throttle, it implies a possible software issue with a bit flipped to 1 as soon as the value reaches a certain point--such as say, a binary 16-bit value of 0000000011111111 representing a voltage just below half of full value, increase one bit more and it's supposed to go to 0000000100000000 but instead goes to 0000001100000000, which would be higher than full throttle, and if that bit gets "stuck" (not cleared by the software, not written to do this), then even if you rolled back throttle to off the value would stay stuck to 0000001000000000...if the software still reads that as full throttle, then throttle is now stuck full on regardless of what you do until you power cycle it or do something else that causes it to reset that "register".

While I suppose there could still be one, I can't think of any analog hardware failure that should cause something that's at half of a voltage range to jump to the max of that range and get stuck there, unless there is an external ADC outside the MCU with an internal register that's stuck the way described above, or the ADC connects to the MCU via parallel data lines instead of serial, and one of the data lines is open-circuit and under these conditions it floats to a 1 instead of staying at a zero.

 

[afzal]

At WOT malfunction, sense wire to ground is still .75v, so there's something hosed up on the board apparently.........

Was it checked at the connector pin on board?

 

[eee291]

Post your settings, there could be something out of the ordinary.
Or you could reset all settings and start over to see if the issue still persists.

 

[Barncat]

Guys- I took the V readings midway on the 3 wires connecting ADC1 throttle to board. The +3.3v hot and ground wires are of course wired in parallel to the ADC2 regen thumb throttle and each throttle has separate sense wires going to their respective pins.

Unless i badly misunderstand this, a .75v reading instead of over 3v at WOT on ADC1 sense to ground means the problem is in the board, or possibly some new software glitch. As you mentioned amberwolf, there's no way Hall throttle hardware can cause this particular scenario. And V on both throttles rose and fell normally on the wizard graph interface when trying the reset.

I'll have to refresh my memory on reloading firmware if I'm going to tangle with that, and certainly disconnect the chain to rear wheel for any more testing.....

 

[eee291]

I'll have to refresh my memory on reloading firmware if I'm going to tangle with that, and certainly disconnect the chain to rear wheel for any more testing.....

When you press Setup motor FOC, it asks if you want to reset settings.

 

[Barncat]

eee291- yes, there is a notification pop up, but firmware update is done on a different part of the menu. Like anything else one only does once a year or so I'd have to go find my notes. There's a risk of bricking the board if you do it wrong.

To Tronic's credit, they responded immediately to my email notifying them of the problem, and offered a no questions asked exchange for a new unit. Very generous for a complex electronic part. I however am sending it back so they can do their own assessment, and possibly send a refund. So i guess that's it for now and thanks for the suggestions guys.

 

[amberwolf]

As you mentioned amberwolf, there's no way Hall throttle hardware can cause this particular scenario.

Well, my statements were not to say that the *throttle* hardware couldn't cause it, but that *none* of the hardware (throttle, or anything on the board between the ADC-hardware (MCU?) input pin and the throttle input connector, could cause it, other than the ADC itself or the software/variable/data-memory locations (which, AFAIK, is all inside the MCU chip).

And V on both throttles rose and fell normally on the wizard graph interface when trying the reset.

Just to clarify, do you mean that the WGI shows correct throttle readings even when the problem exists?

Or only *after* resetting the system after this event starts, so that the throttle operates the motor correctly again during those readings?

If the former, then if that is generated from the MCU that accepts the throttle input, then it cannot be a hardware problem with the board up to the ADC itself, or it could not read the correct throttle voltage to be able to display it. It would have to be something in the motor control software portion *after* the point at which the WGI pulls it's data.

 

[eee291]

There's a risk of bricking the board if you do it wrong.

Resetting the settings has nothing to do with flashing new firmware! The program simply loads the default values that are already in the firmware. But I guess it's too late now.

 

[Barncat]

Inferred in my description throughout was that both the original and brand new throttle tested were springing back to closed and functioning normally, and showed as nominal on the WGI- during the malfunction-which never corrected.

And yes flashing firmware differs from just resetting parameters. Would have been a last resort, and is simple if you do it a lot, but under the circumstances i just threw in the towel...

We'll see. Part is in mail back to manufacturer.

 

[amberwolf]

Inferred in my description throughout was that both the original and brand new throttle tested were springing back to closed and functioning normally,

Sure, but ; my question wasn't about the throttles, only about the voltages on the board itself, between the input connector and the MCU, because that would have determined if there was or was not a hardware issue.

and showed as nominal on the WGI- during the malfunction-which never corrected.

If the WGI is generated by the same MCU that does the motor controlling, then it has to be a software issue (or defective memory location causing a software issue), since the hardware to read the throttle voltage at the MCU pin must be working correctly for the WGI to read correctly during the fault, while the controller portion reads (or at least behaves) incorrectly.

Not that it matters now for your case, but if you run into a similar issue ever again (or anyone else does and runs across this thread), then if they have the same testing results they'll have a probable answer why it's happening.