DIY Pedals & Buttons Controller

Hi all!

Just want to share my new project - pedals & buttons controller.
It can be used for DIY buttons boxes, button rim plates, pedals, hand brakes, gear shifters, etc, etc — everywhere you need joystick/gamepad interface with PC.

Device capabilities are:

• 6x 12-bit (4096 steps) axises
• rotary encoders support
• rotary switches support
• matrix buttons support
• single buttons support
• axises calibration
• analog inputs as buttons
• 1kHz exchange rate with PC, which means 1ms maximum latency for axises

TBH, specs not so bad
For example, 4096 steps for axises if better then Logitech G27 (256 step) and Fanatec Elites (1024 steps).
And 1kHz rate is also very good, it means 1ms latency for axises (G27 has 2ms latency, Fanatec Elites has 16ms and DSD 12 bit controller with integrated load cell has 20ms)


For the project I choose little STM32F103C8T6 minimum development board. Its more powerfull and cheeper then Arduino. For example, here is brief comparison with Arduino Leonardo board

One big drawback is that you need additional external programmer. But its not expensive also, total price for mini board + programmer is still comparable with Arduino clones.

Pics of these little things




I bought both items on aliexpress.com, search for «STM32F103C8T6 Minimum System Development Board» and «ST-Link v2 mini», for example this and this.

Schematics of the board

Here is pinout you get after flashing the firmware first time:




Also I programmed small PC-based app named OSHStudio, which allows you to choose a function for each pin. Pins’ functions can be selected in the «Pins Configuration» tab, also here you can choose your board type. Here is how the initial pinout looks in OSHStudio, when you click «Get Config from Device»:




Buttons

When buttons wired in matrix, columns have to be connected to Button Matrix COLUMNS pins, rows — to Button Matrix ROWS pins. Single separate buttons (not matrix), can be connect to «Single Button +3,3V» or «Single Button GND». If you connect button to «Single Button +3.3V» than connect the other side of button to +3.3V, if you connect button to «Single Button GND» than connect it to GND. Here is an example of matrix wiring:



You can test your buttons in the «Buttons» tab of OSHStudio:



In this tab you can also configure POV Hat switches. When activated first Hat Switch used first 4 buttons of matrix, 2nd Hat Switch — from 2nd 4 buttons and so on.

Also here you can tune threshold of analog inputs, after that buttons press will be registered (for Analog to Button pin types)



Rotary Encoders

The firmware supports full step, half step and quarter step encoders. Rotary encoders can be wired in «chained» or «single» configuration. Chained config means you wire side encoders’ pins (PINA & PINB) together and central pin become «control» pin. Central pin identified your encoder type — 1/1 (full step), 1/2 (half step) or 1/4 (quarter step). You can wire different type encoders in one chain.

Schematics:



Also encoders can be connected in single configuration. In this case you should configure side pins according to the type of encoder and central pin have to be connected to +3.3V.

Schematics:




If necessary you can remap encoders pins on the «Single Encoders Config» tab.




Encoders can also be tested in the «Buttons» tab.



Rotary Switches

Virtual button is «clicked» when shaft is changing position.




Axises

Analog pins ADC0 — ADC6 used to connect potentiometers or other analog inputs. Also you can calibrate axises in OSHStudio, and calibration values in this case will be stored in MCU itself. After calibration an axis is «expanded» by the controller, so PC always sees axis as 4096 steps. There is also a possibility of AutoCalibration of axes.

As you can see, there is also «Combined axis» function. It means you can combine 2 analog inputs in one axis. The function is mainly intended for rims with 2 clutch paddles. There are 2 possible modes:

• cooperative work — in this mode results from both analog inputs are summarized. You can choose weight of each input by slider.
• each on his own — each analog input works independently but for one axis. For example you can short calibrate an one input (paddle) for fast gear changes and an other calibrate as normal axis — for starting.

Notes
I recommend set to «Not used» all unused pins

Available firmware:

Version 0.14 — Autocalibration axes, Analog2Button pin type and combined axis added

Version 0.13 — Single Encoders Config tab added

Version 0.12 — Tuning tab added

Version 0.11 — Single encoders support added

Version 0.10 — base version

If you wonder how to flash firmware to the board you can check this post — How to flash firmware to STM32Fx
Project URL -https://opensimhardware.wordpress.com/pedal-button-controller/

awesome project. I think i may order a board and programmer and try it out. I want to get rid of my hacked up site joystick i am currently using for my pedals to clean up aesthetics.

thanks!

@PiaMan, yes components are cheep enough just for try it out.

Testing the controller with DXTweak and G27 pedals (better to watch in full screen and HD):



forgot to leave TODO list:
- make PC based configure app which allows to choose different number of encoders/buttons/axises
- make PCB including integrated load-cell amplifier
- add support of another controls like rotary switches, on/off toggles. etc

Great project man...thx for sharing...
it would be possible to create a firmware that accept a pov switch?

@EduardoMoreira its possible, but not in nearest plans..

Thank you for your project.
I can not find the Arduino code in github project, if you could tell me.

Thank you

Hi @zigzag49 ,

the firmare is not for Arduino, but for stm32f103 mini dev board. Its binary file (ready to upload), but if you would like to take a look on a the source code, you can find it github project

Ok thank you I confused .
I'll look in more detail

This project look interesting, I'm following closely

That's new around her!
Congrats! and thanks for sharing

Awsome news! Thanks for sharing!! I will try it out thanks a lot!

thanks for this project. works a charm. have some buttons to replace that are not working but it was a lot easier to get working compared to the Arduino version

Glad to hear it works
Currently I'm writing app that will allow to configure a type of pins on the fly, so hopefully it will easer to use it (soon )

fancy 2000 don't post in every thread with "nice build" to get coins !!

TOPMO3 i have a problem.
I had to reassemble the button box as some buttons where not working and my supplier also mixed up a few n/c buttons in my order.
sorted out the buttons to be all n/open and all working.
Now my issue is none of the buttons will work
The encoders work fine.
The 2 shifter buttons are working but show the same button number in the game controller properties.
Hope you can advise and possibly show me where i have gone wrong.
my layout attached.

Hi @razzor13bt
You know, your layout seems correct to me. Can the problem lie on a hardware side - i.e bad connection/soldering etc?

sat late this afternoon with it.
Resoldered with new thicker wire, not the wire breadboard jumpers the electronics shop supplied.
also used a multimeter and checked continuity and also put it on ampmeter to use to bridge terminals on the board.
noticed occassionally a light lit up on the game controller display, was when i bridged col6 with row1 or row2.
Turns out its the same light that lights up when i touched the row 1 or 2 terminals. cant recall properly but it was number 27 or 29 in the game controller display.
Will try again tomorrow evening after work.

The ARM is being powered by a usb cable connected to a usb hub with a 2amp 5v supply.

I had a chance today to work on it. spent last 3 hours checking everything.
I only get the following buttons to work as per pinout pic in the 1st post.
As mentioned before all 4 encoders work.
I get b4-row1 working with col1-c13, col2-c14, col3-c15, col5-b3, col6-a7.
col4-b12 does not work.
row2, row3, row4, row5, row6 all do not work with any of the columns.

Have to try and get off work to go and buy another board in case it is the faulty part.

well, its really strange. If you don't use analog inputs (A0-A6), I can make firmware which will utilize them for row1 - row6 for you.