mcduffchannel

Hacking Hardware Towards an Ethos

WowGo / Meepo ESC Version 1.5 Reactive LED Brakelight

29th January 2019

 

This write up will be more orientated around showing you how I modified my WowGo Electric Skateboard in the best detail I can, rather than a 'step by step' on how you should make your own. Nevertheless, by the end you should have more than enough information to engineer a specific solution to your needs. 

WARNING: this modification is not for the faint of heart as you will be working with ~40v and soldering directly onto your ESC. You will undoubtedly void your warranty. I take ZERO responsability for any unfavourable outcome... Unless its flawless, then it was all me!


Shopping List

Heres what I used:

• A late WowGo ESC Ver 1.5, from early 2018, but from what I can tell from researching is that similar boards such as the Meepo use the same ESC.

• 2 x Individually Addressable LED Strips with 28 LED's each (total 56). I used the a 155 long strip of Luminosum I grabbed off of Amazon for about $55 AUD.

• 1 x LM2596 (Max 30v) Voltage Regulator. Depending if you have an available voltage rail on your ESC that supplies 10v ~ 14v, you may have to buy a LM2596S which allows a Max of 40v and instead power your circuit directly off of your battery with a manual ON/OFF switch (more on this later).

• 1 x ATTiny85: and not just the knowledge of how to use Arduinos but the knowledge on how to load code onto a ATTiny85. Heres a link to where I learnt to code load on to ATTiny85's Here

• 1 x 10K Ohm Resistor, if unavailable use a ripe banana.

• 1 x 4 wire plug, not required but is convienient during development.

• 1 x 3 wire plug, required to disconnect circuit from LED arrays.

• Soldering Iron with a good small point as the ESC is crowded.

• Assorted wires and heat shrink.

• Hot Glue.

• Thick foam double sided tape. Not required, but is an easier solution.

• Assorted tools; wire snips, wire strippers, screw drivers, etc.


Step 1: Take off all your bits

First thing we need to do is strip your board down;

• Start by taking off your battery housing.

• With the housing released, disconnect the XT60 connecter from the battery.

• With the battery disconnected, discharge your ESC by turning on your board. Should hear a single beep.

• Now remove your ESC housing.

• With the housing open disconnect the XT60 connector, aerial, motor bullet connectors, motor signal wires (Take note of which motor wires are on which side as it may not be obvious for some).

• Now remove both front and rear wheel trucks.

 

If successful, you should have a fancy looking Ikea chopping board.


Step 2: Design, Test, Design, Cheer!

So as I mentioned earlier, this wasn't going to be a complete 'play by play', but more of one of those, teach a man to fish scenarios by showing you how my design worked. So please study... read the below bullet points, that expand on the lower diagrams.

10v ~ 14v - Under the cardboard slip of your ESC you should find a 'through hole/jumper' as indicated on the diagram. When you locate it, best to test with a multimeter with the ESC powered ON. Should read between 10~14v. Using this as a power source is important as it only has power while the board is ON, and unlike the many other 5v rails located around the board this can handle the Amps. If you try to power the circuit directly off the ESC anywhere else, the excess Amps will trip the ESC into a safety mode. The bucky booster will ensure a constant 5v either though this point isn't a consistant voltage.

 

Throttle signal - with multimeter should be ~0v at rest, and change relative to throttle position, upto ~4.9v for acceleration or braking. 

 

Brake signal - with multimeter should be ~4.6v at rest, ~0v when brake is applied.

 

Negative - Any of the many negative points work, this one was just the closest to where I had the Bucky Booster.

• I used a LM2596 voltage regulator, this can handle a max input voltage of 30v. If you decide to power it directly from the battery and not the ESC using a manual on ON/OFF switch on the earth, you need to use a LM2596S as it can handle the 40v from the battery. Before supplying power to the ATTiny85. ensure you adjust the output voltage using the trimpot to 4.95~5.00v.

 

• A 4 wire plug isn't required, I had one in their to facilitate the development, and left it in.

 

• A 3 wire plug is more important though. This allows you to disconnect the ESC from the LED array attached to the board.

 

•  The 10K Ohm Resistor is to bias off of the signal from the brake. Simply needs to go to the ground, otherwise your board will go into a bonus mode called 'possessed' and do random s#!t.

 

• The LED's are configured parrallel in 2 x 28 arrays, so either though their are 56 in total, we treat them as 28 and both side behave the same.

NOTE: I recommend prototyping everything on an Arduino Uno prior to commiting to the ATTiny and installing in the ESC. Also once your code is loaded onto ATTiny, test test test. As you're also soldering from above the PCB, ensure your wires are only 2-3mm long. I have no idea whats underneath.


Step 3: Install Your Lights

Theres a thousand ways to do this, however heres how I did mine;

• Cut my LED's into segments (this is my last resort) to follow the shape of the board.

 

• Applied the LED's to my board with the 3M adheiseve that comes on the LED's. My original plan was to route out a channel for them to rest in, then pot it with resin. Then I couldn't be bothered.

 

• To rejoin the LED's at the cut points, I simply used copper core out of a network cable stripped bare of insulation.

 

• Once I was sure the LED's worked and I was confident, I sealed each join with hotglue.

 

• To run a wire up the center from the LED to the ESC and ensure the wire doesn't get pinched by the trucks, you only need to cut a 1cm notch in the center on the riser pad for the wire to run under the truck into the (refer to the photo).


Step 4: The Code

Before I get to showing you how I fit everything in the ESC housing, lets cover the code and then you can get back to man handling your board. You can grab the code off of my GitHub   

 

https://github.com/mcduffchannel/WowGo-LED-Scanner/blob/master/LED_Scan.ino

 

Ensure you install the 'Adafruit NeoPixel' library.


Step 5: Tetris Hard

So to fit everything in (noting the orientation of how I have the ESC in the photo):

• I routed the motor wires down the right hand side to keep them out of the way.

• I sat the voltage regulator to the left.

• I sat the regulator on nylon posts that I hot glued to the enclosure so I could still screw it off if I need to (I blew up 2 regulators, so yeah I needed to).

• The rear of my ATTiny circuit was insulated with thick double sided foam tape to prevent it shorting out and stuck it to the left on the enclosure wall.

• I then reinforced it with hot glue.

• Cable tie everything so its "noice n toight"


Fin

So once you slap everything together I hope you are just as successful as I have been.

 

As I didn't document anything as I went along I do appologies if I missed anything. At the same time this is the first time I've written up a 'how-to'.

 

Down the track I hope to make a video that accompanies this write up. But if you have any questions, leave a message below and i'll try my best to get back to you. In turn if I find your question important for everyone i'll edit the write up to include it.

 

Thanks for reading!

 

- Scooter McDuff


If you need help leave a comment! If its a good question I'll edit my write up to cover it.