Trying to decode LCD signal from cheap brushless motor controller

SomethingsFishy

100 µW
Joined
Oct 30, 2021
Messages
8
Does anybody know how to use this cable shown in the picture?
Manufacturers don't appear to agree on one cable name, I've seen "autometer signal", "speedometer signal", "lcd screen signal"
and a bunch more written for this one cable.
I haven't been able to find any info at all about this, neither anyone actually using it, tho it's always there.
Also, I searched for an LCD screen that would take that cable as an input with no result.
Some sellers define it as "Debug", so maybe it is used in the manufacturing process for debugging, still no idea.

I'm trying to build a custom lcd screen with arduino, and my main goal is to be able to read the rpms of the motor, so then I can
calculate the speed the wheel is turning. I know I could do a workaround by reading the signals of the hall sensor from the motor,
but it would be amazing to decrypt the data from that "lcd display signal" cable of the controller. Thanks in advance.
hihj.JPG
I contacted the seller, but because they are not the manufacturers, just resellers, I wont expect anything useful from them.
wdwadwada.JPG
Also if anybody is wondering what am I working on:
It's an old school bike from the 80s, model: motoretta gac. I bought a 2000W max motor, an accelerator and a 350w controller
(all used) for 50 euros, dirt cheap, tho instead of the 350w controller the one with 1000w (that im trying to decode), that has a
max of around 2000w as well, aiming for 60km/h with great torque.
Screenshot_20211031-014459_Video Player.jpg
 
That green wire is for old or more analog speedometers, its usually connected directly to a motor phase internally.
Iv'e seen this discussed on here a few times, those kinds of posts aren't easy to find even with the search function.

I recently saw this method still being used by those rickshaws that are starting to pop up everywhere.
 
Wait really? At the beginning of my research I was thinking it could be one of those, but because I did not see an analog indicator on any ebike or scooter I thought it wasn't possible.

Well anyways this is good news! Now I have two options, either use that analog signal and read it with my arduino, or use an analog dial, some dials look pretty cool, so I might end up using one of those instead of the arduino, still I won't remove it, ill let it for max power, acceleration curve, shunt meter reading and a bunch of functions more.

Also, guess the seller's reply.
dwadwd.JPG
That's right, he didn't even bother reading the other message.
 
Well what can you expect, the seller probably buys them from a wholesaler or whatever is on sale at the moment.
Not to mention the language barrier.

If you want seller support in regards to controllers you should look to Greentime or Quanshun on Aliexpress.

https://evfittinggreentime.aliexpress.com/store/313864
https://siaecosys.aliexpress.com/store/5881618
 
I made an analysis of the UART communication some time ago:
https://www.pedelecforum.de/forum/index.php?threads/brainpower-motor-controller-250w-mit-s866-display-versuch-einer-funktionsanalyse.89310/post-1705760

regards
stancecoke

index.php
 
If you wire up a motor enough to make it spin, you could put an oscilloscope on the "autometer" signal line and see what it looks like. My guess is it will be a buffered copy of one of the hall sensors. I haven't seen an analog speed output on a controller before.

More likely you will need to use one of the hall signals to get the speed. This is how most of them I've seen work.
 
If it's like a number of cheap nonprogrammable scooter and "motorcycle" controllers, that "autometer signal", "speedometer signal" wire is typically directly connected (sometimes thru a resistor) to one of the phase wires, so it typically carries full phase voltage on it. I don't know if these are are commonly available separately or only on the vehicles they come on.

The displays on those don't generally look like the ones seen on programmable/settable ebike controllers, but they typically have an input wire specifically for this phase-voltage signal, (sometimes also have one for a hall sensor or magnetic/reed wheel sensor).


You can find out by hooking up the controller to everything else and running it with the wheel offground, then measuring the voltage on that wire, with your meter set to 200vdc and hte black lead on battery negative, and the red lead on that wire. If it's a phase wire, then you'll read a voltage changing from near zero to near battery level as you vary throttle from zero to full throttle.

If it instead reads around 0-5v or around 2.5v, then it's probably a hall sensor output.
 
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