Open Source Electric Skateboard Platform

ESK8 Electronics
1

Hello everyone,

I’ve have been working on an opensource electric skateboard platform for a few years, I think I started this project before Boosted Boards Kickstarter.

I have now built and tested 3 major prototype revisions and feel that the project is mature enough to gauge the communities interest and engage with potential beta testers.

The platform consists of the following parts:

Main Controller 2x ESP32 modules supporting Bluetooth 4.2 and WIFI with modified 16MB flash Supporting Bluetooth Remote and potentially a smartphone app Bluetooth bonding, encryption and MITM protection supported Programmed on the esp32 Arduino core for maximum accessibility OTA programming over wifi and Telnet command console The main ESP32 is responsible for communicating with the Bluetooth controller, IMU via I2C and VESC via UART The sub ESP32 is responsible for data logging, communicating with the LIPO charge controller, BMS and electronic fuse.

USB Hub for ESP32 programming and VESC USB passthrough

SD card slot for data logging

MPU9250 IMU for torque vectoring and orientation sensing IMG_20180811_092007 IMG_20180811_092043

A previous version of the Main Controller running 2x STM32F3 MCUs, has NFC built in however the anntenna wire required was too long so the NFC read was not realiable IMG_20180811_085259 IMG_20180811_085317

BLDC Controller 2x VESC v4.12, firmware based on fw 2.18 I have added additional packet types so that only essential information is sent to and from the ESP32 which reduces latency and increases refresh rate.

BQ24610 LIPO charger supports up to 6S and 10A

LT8640 DC-DC regulator outputs 3.3v up to 5A provides power to the Main Controller board and the VESC microcontrollers

LTC2951 soft power on switch/reset controller

IMG_20180811_085655 IMG_20180811_085736 IMG_20180811_085826 Remote Control Infinite scrolling controller The total power draw with the screen on and Bluetooth transmitting is under 15ma
DA14583 M0 Cortex and BLE 4.2 SOC Bluetooth bonding, encryption and MITM protection supported Programmed on the SemiDialog SDK which is C, unfortunately, I could not find any SOC that comes close to this one that supports Arduino As far as I know, there are currently no SOC as low power or as compact, which will allow a wide range of controller form factors in the future.

96x16 OLED Screen

LTC2951 soft power on switch/reset controller

Haptic feedback motor

MCP73831 LIPO charge controller

Induction charging support IMG_20180811_084436 IMG_20180811_090631IMG_20180811_090650

A previous prototype with DA14580 IMG_20180810_084047

BMS BQ76PL36 cell balancing up to 6S, this is stackable for more cells (Tesla uses the same controller in their battery packs)

The only one I built is inside my battery pack so I’m only showing the PCBs IMG_20180811_090210

Electronic Resettable Fuse Programmable trip current via I2C, no microcontroller all functions carried out at using simple transistor logic 4x IRFS7530 LT1910 high side MOSFET driver ACS756 current sensor LM393 voltage comparator which turns the LT1910 on/off based output from ACS756 2x AD5259 I2C digital potentiometer for adjusting trip current

The only one I built is inside my battery pack so I’m only showing the PCBs and this part still requires additional testing

IMG_20180811_093325IMG_20180811_093338

My current setup I’ve been using this as a daily commute for a while hence the dents and sratches IMG_20180811_091326 IMG_20180811_091348

Back panel containing the Bluetooth/WIFI antennas, magnetic charge port and USB programming port IMG_20180811_091040

Thank you for your attention let me know your thoughts below!

20 Likes
2

This is a pretty cool project and congrats on putting so much work into it. It would be cool if the battery module could do up to 13s though as many boards now use higher voltages

3

Great job, look forward to your sharing

4

Awesome , how does controls Via ring feel?

5

Thanks, the BMS can be stacked and can easily support up to 192 cells so that’s the easy part.

Supporting 14s charging might be more difficult but can be done with IC’s such as MC33771.

I understand 14s is the max voltage the VESC can take.

I’ll put it in my next revision, if someone has a better way of doing this please let me know.

6

I think you get finer control of the acceleration and braking as it is not limited to 180 degrees. It is also immune to sudden acceleration and braking as you do not have to keep you finger on the ring. It uses a safety switch to go between acceleration/braking and coast mode.

Holding down the safety and scrolling up to accelerate, scrolling down decreases the amount of acceleration, past the coast point switches to braking. To quickly switch to braking release and reengage the safety and scroll down.

The ring controller is just an example of what can be done with the DA14583, you could build any type of controller you can think of using that platform.

7

Thanks, I’m hoping individuals will join the development and create an open source and user-friendly platform,

8

congrats for such dedication. Keep it going man.

1 Like
9

That remote looks like the original design from the boosted Kickstarter! Did you work with them on it perhaps?

10

Nope, I didn’t work with them.

It’s one of the ideas that I had early on, I guess it’s a coincidence, but back in 2010 there was no way that the ring controller could be built due to the battery constraints, I had a similar design with a much longer tail but due to the battery drain it would only last 1-2hrs so I shelved the idea. I was actually very curious to see how the team at Boosted would pull it off, clearly, they also couldn’t make it viable.

In the meantime, I worked on other controllers like this glove controller below. IMG_635517449491825530

But once the DA14580 was released I started working on the ring controller again as the glove controller was a bit too fiddly to implement reliably.

3 Likes
11

This is really inspiring stuff. I’m working on my electrical engineering degree right now, so I don’t think I would be of much help. I have just started learning Eagle for designing circuits though. At any rate if you need any testing or help with the project let me know.

1 Like
12

What trucks are those?

13

Nice work man, keep it up!

1 Like
14

That’s great! I have no formal electrical/mechanical engineering training myself so don’t limit yourself as to what you can achieve. I think KiCad is much easier to use in my opinion, give it a shot if you have time.

Thanks for the offer! I’m working on some code to run on a off the shelf ESP32 dev board which has a screen and LIPO charging circuits to use as a remote, see this thread

If you have a skateboard build and are happy to test out the remote/receiver pair that would be great!

I’ll be rewriting some code from my current build to run on a single ESP32 to control the VESC

15

I designed them and got them CNCed :grin:

16

Looking into @pat.speed suggestion I think this LIPO charger would fit the bill http://www.analog.com/en/products/ltc4020.html

It’s a buck-boost charger capable of supporting battery packs up to 55volts

Am I correct in thinking most people who use high voltage pack use LifePO4 chemistry?

So at 14S it would be 3.6x14=50.4V

One advantage of this charger IC is that it has a boost mode which means that your AC adaptor can have a lower voltage than your battery pack, which I think will be very convenient.

The issue I am tackling now is what is the best way to set the charge voltage as different people would have different pack voltages, would people be happy to solder on the correct resistors to set the charge voltage or would a digital potentiometer implementation be better?

The only issue I can see with using a digital potentiometer is if someone hacks the controller they can change the charge voltage and blow up the LIPO pack.

@ggalisky What do you think?

Please let me know if any of you have thoughts on this issue

17

I have a boosted inspired board, 10s4p Samsung 30Q, dual focbox and torqueboard 6355 motors. I’d be happy to test and record data on parts for this project. Feel free to PM me.

18

Hey man, I was wondering if you had a link to your code used for the esp32 board? I had the same idea to use an esp32 to control the board I am building for my brother and having your source code as a basis for me to modify for the esp32 devkit I purchased. I was also planning of posting my updated code on here when finished and have tested and will be more than happy to give all credit to you for the huge assist. If you are cool with lending me your base code my email is nicktitushr@gmail, much appreciated