Smart Control Box for Simhub

The Smart Control Box is a harness tensioner control box reserved for Pro and Elite contributors.

Summary :

  1. Presentation
  2. Caracteristics
  3. Shopping list
  4. 3D files
  5. Wiring
  6. Drivers settings
  7. Arduino code and Simhub Configuration
  8. Assembly instructions
  9. Réglages additionnels

1) Presentation

The Smart Control Box Uno lets you adjust gain and preload directly, to avoid situations where the tensioner becomes unpleasant (single-seater) or, conversely, where you don’t feel it (slow car).

It also enables you to activate the tensioner on the gas pedal and brake, and switch off everything else.

To put it simply: all you have to do is launch the Simhub software, and everything else will be done using the Smart Control Box.

Exclusive to Pro and Elite contributors.

2) Caracteristics

3) Shopping list

  1. 1 x Arduino Uno Rev3 (Aliexpress, Amazon)
  2. 2 x Potentiometer 10k Ohm (Aliexpress, Amazon)
  3. 3 x switch (Aliexpress, Amazon)
  4. 1 x 2″ screen TFT (Amazon, Aliexpress)
  5. 1 x MCP4725 (Amazon, Aliexpress)
  6. 8 x M3x8 screw and nut
  7. 1 x M2x8mm screw

4) 3D files

The 3D files are available on the download page.

5) Wiring

NOTE: The harness tensioner can be dangerous. At full power, it is used a lot around the collarbones. Therefore, an emergency stop button should be provided.

Make all connections without power.

Perform all tests without any parts on the motor shaft.

Once the tests are done, and the belt is installed, perform the tests in 10% power increments, always being able to cut the power.

Câblage du connecteur DB25 (vous pouvez utiliser les pins du GX12 comme vous le souhaitez).

ArduinoDB25 connector

Switchs, buttons wiring

Switches and buttons are wired on the double row opposite the USB connector:

Switch :Arduino :
Switch (Throttle)4/5
Switch (Brake)2/3
Switch (Power)6/7

Potentiometers :

Potentiometers:Arduino :
Gain SignalA1
Preload SignalA2
Additionnal GNDA3
Additionnal 5VD8

MCP4725 wiring :

MCP4725 :Arduino :
OUTPin 25 of DB25 connector

Screen Wiring

Des photos du câblage de l’écran sont disponibles dans cette archive.
simhub tensioner wiring

6) Drivers settings :

The parameters are the same as the original ones. We can, however, afford a higher gain on the driver, as it will be adjustable (once again: only increase this parameter once the installation is stable). You can also reduce the preload, as it can be increased (but not reduced) via the potentiometer.

7) Arduino Code and Simhub Profile

To install the arduino code, you need to use the IDE supplied with the code. It’s available on the download page.

Then in Simhub>Arduino>My Hardware, once the Arduino board is recognized and connected, click on “Edit”, and add the following lines:

'11' +  ';' +
format([AccelerationSurge]*40,'0' )+ ';' +
format([AccelerationSway]*40,'0' )+ ';' +
[DataCorePlugin.GameRunning] + ';' + 

The first number (11) is the gain. If you increase it too much, a message will appear on the control box, indicating that the values received exceed the tensioner’s limit.

If you have an error in the Raw result, please check if the ‘ are correct (no “, or anything else). Please also try while ingame. Often it doesn’t work when the game isn’t launched.

8) Assembly instructions


9) Additional settings

The gain: the gain (clamping force) can be adjusted in three places:

  • On the driver: PN189 manages force
  • In simhub: the first number (11 by default) is also a multiplier
  • Via the potentiometer on the control box (multiplier between 0 and 1).

The idea is to find a general setting on the driver and simhub (using a GT4, for example) and then adjust it on the fly using the potentiometer.

I've been passionate about cars since I was a kid! I learned the multiple variations of the Skyline R34 through the Gran Tursimo series, until I discovered GTR2 at the wheel of a keyboard. A few years later, I plunged back into Sim Racing with a G27 which made me enter the DIY world. Always looking for an immersion out of reach in reality, I develop projects that I take care to make accessible to any 3D printer owner!
Posts created 92

4 thoughts on “Smart Control Box for Simhub

  1. Wow, this is brilliant. Thanks for developing it!

    Are the TFT and Potentionmeter necessary, or can the control/display be achieved via a Simhub Dashboard?

    Best regards

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