Making an Scale using Arduino,HX711 and loadcell - Data is constantly increasing

Using Arduino Sensors
1

Hello, I made a scale using HX711, an Arduino UNO and a loadcell with a code that I found and changed it a little bit to best fit my case and it was working great. Now I am trying to build another one but there is some problem with the outputs. They get constantly increased. For example when I connect the wires let's say I get a number like 120 g. It must show 120 (maybe one or two more or less) without any change. But it doesn't and the number gets increased constantly. I have checked the wires multiple times and I know they are correct. What I think is that either my loadcell or hx711 is corrupted cause I have used my arduino in other cases before so I know that it works fine.

Here is my sketch:

#define DT A0
#define SCK A1
#define sw 2

long sample = 0;
float val = 0;
long count = 0;
int counter = 0;

unsigned long readCount(void)
{
    unsigned long Count;
    unsigned char i;
    pinMode(DT, OUTPUT);
    digitalWrite(DT,HIGH);
    digitalWrite(SCK,LOW);
    Count = 0;
    pinMode(DT, INPUT);
    while(digitalRead(DT));
    for (i  =0; i < 24; i++)
    {
      digitalWrite(SCK,HIGH);
      Count = Count << 1;
      digitalWrite(SCK,LOW);
      if(digitalRead(DT)) 
      Count++;
    }
    digitalWrite(SCK,HIGH);
    Count = Count^0x800000;
    digitalWrite(SCK,LOW);
    return(Count);
}

void setup()
{
    Serial.begin(9600);
    pinMode(SCK, OUTPUT);
    pinMode(sw, INPUT_PULLUP);
    delay(1000);
    calibrate();

}

void loop()
{
    count = readCount();
    int w =(((count - sample) / val) - 2 *((count - sample) / val));
    if(counter < 1)
    {
        Serial.println("");
    }
    Serial.print("weight:   ");
    Serial.print((int)w);
    Serial.println("g");
    if(digitalRead(sw) == 0)
    {
        val = 0;
        sample = 0;
        w = 0;
        count = 0;
        calibrate();
    }
    counter++;
}

void calibrate()
{
    Serial.println("Calibration initialized!");
    delay(3000);
    Serial.println("Please Wait till the Process is finished!");
    Serial.println("");
    delay(4000);
    for(int i = 0; i < 100; i++)
    {
      count = readCount();
      sample += count;
      Serial.println(count);
    }
    sample /= 100;
    Serial.println("");
    Serial.println("Please put a 100g weight and wait!");
    Serial.println("");
    delay(5000);
    count = 0;
    while(count<1000)
    {
      count = readCount();
      count = sample - count;
      Serial.println(count);
    }
    Serial.println("");
    Serial.println("Weight loaded, please wait a little more...!");
    Serial.println("");
    delay(4000);
    for(int i = 0; i < 100; i++)
    {
      count = readCount();
      val += sample - count;
      Serial.println(sample - count);
    }
    val = val / 100.0;
    val = val / 100.0;        // put here your calibrating weight
}

Any thoughts about what the problem can be? Or any way to determine which part is corrupted?

2

Please post your full sketch.

If possible, you should always post code directly in the forum thread as text using code tags:

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3

AliKHalili:
Now I am trying to build another one

[...]

Any thoughts about what the problem can be? Or any way to determine which part is corrupted?

So you have two setups: one working, one not. That makes trouble shooting easy. Start swapping out parts between the good one (known good parts) and the troublesome one.

The load cell itself would be my primary suspect, so start by swapping out that one part, see what happens: if that's faulty, the original faulty setup should now read correct, and the original good setup should now read faulty.

If that's not it, continue with the rest of the parts.

I'm assuming you run the same code and use the same wiring for both, which would eliminate that as potential causes of the problem.

4

Thanks. I'll try that and see what happens.