Tutorial DIY load cell brake pedal (short tuto)

Hi Tony.
I had experiencing the same things.
first order of INA122P worked perfectly.
Second order of INA122PA . Never work. In 5V could only lower to 1.6 max. And won’t work under 3V .

Seems is nothing about whether is a PA or P.
The seller send me a so called “imported “ chips. INA122PA . Which works perfectly as INA122P as my first order.

Maybe someone could soled this problem with this funny chips.

My suggest will be change to an imported one.
Saving lots and lots of problem.

Trigen
hi, which of the files do you
I made it available for use for the pedals I must use
i will use on arduino leonardo
if I had something written wrong it was the google translator

Copy this code.


Ive been having and issue with the pedals waking up the computer and after some support we figured out it was the setAXIS calls. I have updated the code to include an if statement so that the call to set Axis only happens when its not equal to resting pedal. Its important that you use the println to check what your pot numbers are and input the correct ones in the

Code:

int lastBrakeValue = 0; 

and so on

https://github.com/MHeironimus/ArduinoJoystickLibrary
https://github.com/bogde/HX711

Code:

#include <HX711.h>
#include <Joystick.h>
#define calibration_factor -2300 // Do your calibration first. default 2300
#define DOUT  3
#define CLK  2
HX711 scale;
/*
For the true false flags, use this list. Its all in  Joystick.h
    bool includeXAxis = true,
    bool includeYAxis = true,
    bool includeZAxis = true,
    bool includeRxAxis = true,
    bool includeRyAxis = true,
    bool includeRzAxis = true,
    bool includeRudder = true,
    bool includeThrottle = true,
    bool includeAccelerator = true,
    bool includeBrake = true,
    bool includeSteering = true);
  */
Joystick_ Joystick(JOYSTICK_DEFAULT_REPORT_ID,
  JOYSTICK_TYPE_MULTI_AXIS, 4, 3,
  false, false, true, false, false, false,
  false, true, true, true, false);
 
 
// Variable
int throttle = A0;
// int brake = 2; / no need for this as we read directly from scale
int clutch = A1;

// **** INPUT YOUR VALUES HERE **********
int brake = 0;
int lastBrakeValue = 0;

int throttleValue = 0;
int lastThrottleValue = 270;

int clutchValue = 0;
int lastClutchvalue = 180;

// init joystick libary
void setup() {
  // Ranges are 1023 by default
   Joystick.setBrakeRange(0, 1023);
  Joystick.setThrottleRange(0, 1023);
  //Joystick.setZAxisRange(0, 1023);
 
  Joystick.begin();
  Serial.begin(38400);
 
  scale.begin(DOUT, CLK);
  scale.set_scale(calibration_factor);
  scale.tare();
}
void loop() {

// ***** USE THESE TO CHECK YOUR POT VALUES IN SERIAL MONITOR ****

    //Serial.println (brake);
    //Serial.println (throttleValue);
    //Serial.println (clutchValue);


// For the if else if statements below. Set these to match your numbers as instructed.
// If the value starts below 0 set it to 0. Or if its above 10 set it to 0


// ******** THROTTLE ***************

  throttleValue = analogRead(throttle);
 
     if (throttleValue > 666) {
    throttleValue = 670;
  }
    else if (throttleValue < 273) {
    throttleValue = 270;
  }
    if (lastThrottleValue != throttleValue) {
     Joystick.setThrottle(throttleValue);
     lastThrottleValue = throttleValue;
  }
   delay(1);
 
// *********  BRAKE **************

brake = scale.get_units(); // if the value is inverted put a - sign in front like -scale.get
 
   if (brake < 0 or brake < 8) {
    brake = 0;
  }
 
   if (lastBrakeValue != brake) {
     Joystick.setBrake(brake);
     lastBrakeValue = brake;
  }
  delay(1);
 
// ********** CLUTCH *************

   clutchValue = analogRead(clutch);
 
     if (clutchValue < 185) {
    clutchValue = 180;
  }
    if (lastClutchvalue != clutchValue) {
     Joystick.setZAxis(clutchValue);
     lastClutchvalue = clutchValue;
  }
  delay(1);
}

Good day! Can someone help me with troubleshooting my ina122pa board? Cant seem to get input from the loadcells. Here is my board, could someone please tell if it's correctly built thanks...



now, i dont have access to a multimeter, but ive tried all configurations of the wires from the load cell. still nothing. this is for the logitech driving force pro. any advice?

It looks correct to me. I'd suggest you get yourself a cheap multimeter to help troubleshoot.

Thanks for responding. Yes ive decided to order a multimeter online.
Also a couple of things that i noticed, i had the logitech window open while testing it, once i connect the 3 wires from the pedal to the circuit, brake goes 100% no response from load cell. if i re arrange the wires of the load cell, sometimes what happens is the throttle only goes half way when fully pressed. i wonder what that means. anyhow, ill just wait for my multimeter and see if i can manage to troubleshoot (very basic knowledge in electronics, just learning from google as i go)
thanks again ill post my progress soon

hi all, i still cant figure out whats wrong with my amp. i did some measuring with a multimeter:
first the pots on my logitech dfp- when everything is connected each pot shows 3.8v. i measured the throttle pot and it goes 3.8v to 0.5v (0-100%) the brake goes the other way 0.5v to3.8v (0-100%)
is this why my ina122pa board doesnt work? does it only work with 0v-5v pots?

other thing is when i replace the pot with the ina122pa board, then i measure the voltages it goes down half 1.9v for each. and the brake is stuck at 100% so im guessing what ever voltage comes in the ina122pa board, same voltage goes out on the output pin??? no response from load cell which i already confirmed the correct pairing of wires. does this have something to do with both pedals sharing same 5v and ground?

any advice on how i should troubleshoot is greatly appreciated

btw my components: ina122pa, capacitor cbb22 104j630v, trim pot 3296

It looks like your circuit is configured to output in the correct direction for the brake if the brake requires low voltage at 0% and high at full brake. I haven't tried the dfp, but with the g27, it calibrates each time you plug the wheel in, you have to push the pedals all the way down for it to set the limits. If the dfp is the same, I'd guess it should be ok with the ina122 output. Assuming you're on pc, you can test this by opening the game controllers window ( search for "Set up USB game controllers" in windows 10), plugging the wheel in and opening the controller properties and don't push any pedals. Then push either pedal slowly until the output shows. If it's self calibrating each time, it should show full output when the pedal gets to about half way if you've only pushed it half way.

What voltages go down to 1.9V? I'd double check you're connecting the wires correctly to the ina122 circuit. Maybe try just connecting the +ve and -ve, leave the signal disconnected, connect the load cell outputs but not the power to the load cell, then measure signal to ground/-ve and I think it should be zero.
You could also try measuring the voltage across the load cell outputs with the power and ground connected to load cell. With no load, it should be zero. With the full load if your multimeter is sensitive enough, it should read some small voltage. On mine it was around 8mV.
I've only got quite limited electronics knowledge myself so it's hard to know what exactly might be wrong. It's possible the chip itself might be faulty.

Thanks for a quick reply heres a picture of my board

the voltage on the pedals is 3.8v on the positive and ground, but when i remove the connections from the brake pot, then connect it to my board, voltage goes down 1.9v. I cant figure out why. this happens whether the load cell wires (two 3-wire load cells) are connected to the board or not. if i measure the output signal wire in the middle it shows around the same also 1.9v.

also i tried connecting the board to a usb 5v power, i get around 4.7v on the output signal wire. also same whether the load cells are connected or not. it seems like whatever voltage comes in the ina122pa, same voltage comes out on the signal pin

my load cells are configured like this:
red + black= 1k ohm
red+white=1k ohm
black+white=2k ohm

black 1 + white 2= to power
black 2 + white 1= ground
red wires on the signal pins

when they are connected to the board and i measure the voltage on a 5v power supply, both red wires of the load cells give 2.5v each.

Sorry, I can't think of what else to try. I guess you've already tried that second chip and adjusting the trim pot?

yes i tried both chips. my guess is their not quality chips. maybe ill try to find a way to troubleshoot the chip itself and check if it works right. very frustrating but i want to see if i can make it work, as a challenge maybe. if not i can always just use the hx711 and an arduino. anyway thanks for responding i appreciate it cheers!

hello did not want to disturb you, the code when I do the verification appears error ,, HX711.h: No such file or directory
could be what I'm using only a cellulam load of 50kg and arduino uno ATmega328

you need to install the HX711 library within the arduino IDE
https://github.com/bogde/HX711

Hi guys

I'm completely new to this cicuitry and wiring thing,
Second time to ever solder anything and now a little lost after building the INA122 amp.

* How do I wire the thing to the arduino?
* Which pins on INA122 go where on Arduino?

Thanks in advance!

I'm using this circuit layout which was provided by cteters
See attached file

Mine


Here is what I have in front of me:




Pro Micro reference

S is the Signal from the load cell that you need to connect to the arduino pin that will convert the Analog Tension to Digital values (DAC)

5V is taken from the arduino 5V pin to power the INA
Ground to Arduino Grond Pin: mandatory

yours
Mat

Thanks for the quick reply Mat.

I'm extremely unknowledgeable with electronic terms.
To give you an idea of how I see this stuff, would this be what you mean?

4-cell

3-cell

for 4 wires, yes

for 3 wires, check here https://www.xsimulator.net/community/threads/working-with-load-cells.7340/

@RacingMat
good terde I used the hx711 and it didn't work I intend to use ina122pa according to your post
* doubt in your post has two 1e2 scheme which one should I use?
* in the first photo there are two cells to make the wheatstone bridge I have to press both to work or just one of them
note: my cell load is so three wires
red + black 1000
red + white1000
black + white is not normal?

imagem 1



imagem 2

@I9k[toro] show us your load cell!