200kg Weighing Scale With Indicator Using Arduino and HX711 ADC

Details of the project:

1. Platform scale with 200kg capacity
2. LCD 16X2 Indicator for weight display
3. Wheatstone bridge constructed from four Nos of half bridge load cells of 50kg rating each.
4. HX711 ADC for amplification of bridge output
5. Options for offset and gain setting (calibration) through momentary switches.
6. Calibration using 5kg standard weight.

Follow the below link for an excellent article to know more about using load cells.

https://circuitjournal.com/50kg-load-cells-with-HX...

Step 1: Load Cell Equation

Step 2: Load Cell Wiring

Step 3: Arduino Code

#include
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

#define DT 12

#define SCK 11

#define swgain 9 //switch for gain calc

#define swzero 8//switch for zeroing (offset calc)

long a;

long offset=8876800;

float w;

float gain=47806.5;

void setup() {

pinMode(SCK, OUTPUT);

pinMode(swzero, INPUT_PULLUP);

pinMode(swgain, INPUT_PULLUP);

lcd.begin(16, 2);

lcd.clear();

lcd.setCursor(0,0);

lcd.print("arduino scale");

delay(3000); }

void loop() {

a= readCount();

w= (a-offset)/gain;

lcd.clear();

lcd.setCursor(0,0);

lcd.print(w);

lcd.setCursor(0,1);

lcd.print("kg ");

delay(50);

if(digitalRead(swzero)==0)

offset=a;

if(digitalRead(swgain)==0)

gain=(a-offset)/5.0;

}

// SUBROUTINE Readcount

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);

}