i have wheastone bridge having one strain gauge and three resistors, the strain gauge attached to beam fixed from both ends and force applied at middle of beam , i have made circuit and tested it , work good , now i want to connect this circuit with hx711 module
so that i can read stress , strain in beam from arduino , please guide me how can i connect the circuit to hx711
thankyou very much
Did you get any documentation with the board. Maybe Amazon sells something like that.
There are countless tutorials on line showing how to connect the HX711 to a Wheatstone bridge.
The basic connections are the same, regardless of whether you have four strain gauges or a mixture of strain gauges and resistors.
Bridges with resistors won't work as well, because you lose the temperature compensation.
Check out this link. The board is close to yours.
i wrote a code to read voltage from strain gauge and display on serial monitor but its not working
#include "HX711.h"
HX711 scale;
const int loadCellDoutPin = 2; // Data Out pin (DO)
const int loadCellSckPin = 3; // Clock pin (CLK)
float vRef = 4; // External voltage reference 2.5V to Aref pin
float ampGain = 128.0; // Amplifier gain for HX711
float offset = 0.0; // Initial offset of Wheatstone bridge, if any.
void setup() {
Serial.begin(115200); // Begin serial transmission at 115200 bps.
scale.begin(loadCellDoutPin, loadCellSckPin);
scale.set_scale(); // Initialize scale factor, calibration_factor can be used if needed.
pinMode(A0, INPUT); // Set unused analog pin in input mode.
establishContact(); // Call the function that loops itself till it gets a response from the computer.
}
void loop() {
if (Serial.available() > 0) {
char inByte = Serial.read(); // Store the data sent from the computer
long rawReading = scale.get_units(10); // Get a weight reading in raw units
// Convert raw ADC output (0 - 8388607 for HX711) to voltage (0 - 2.5)
float sgVoltage = (rawReading / 8388607.0) * vRef / ampGain - offset;
// Write values separated with a comma
Serial.print(vRef);
Serial.print(",");
Serial.println(sgVoltage); // Adds a return ("\n") at the end
Serial.flush(); // Wait till serial transmission is complete
}
}
void establishContact() {
while (Serial.available() <= 0) { // Till serial becomes available with a response from the computer
Serial.println("A"); // Send an initial ASCII value.
delay(100);
}
}
from randomn nerd tutorials, I believe this sample code from the library
Use this code to get calibration value
// Calibrating the load cell
#include "HX711.h"
// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 2;
const int LOADCELL_SCK_PIN = 3;
HX711 scale;
void setup() {
Serial.begin(57600);
scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
}
void loop() {
if (scale.is_ready()) {
scale.set_scale();
Serial.println("Tare... remove any weights from the scale.");
delay(5000);
scale.tare();
Serial.println("Tare done...");
Serial.print("Place a known weight on the scale...");
delay(5000);
long reading = scale.get_units(10);
Serial.print("Result: ");
Serial.println(reading);
}
else {
Serial.println("HX711 not found.");
}
delay(1000);
}
//calibration factor will be the (reading)/(known weight)
calibration factor = (reading)/(known weight)
after you get calibration value use this code
* MIT License
* (c) 2018 Bogdan Necula
*
**/
#include <Arduino.h>
#include "HX711.h"
// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 2;
const int LOADCELL_SCK_PIN = 3;
HX711 scale;
void setup() {
Serial.begin(57600);
Serial.println("HX711 Demo");
Serial.println("Initializing the scale");
scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
Serial.println("Before setting up the scale:");
Serial.print("read: \t\t");
Serial.println(scale.read()); // print a raw reading from the ADC
Serial.print("read average: \t\t");
Serial.println(scale.read_average(20)); // print the average of 20 readings from the ADC
Serial.print("get value: \t\t");
Serial.println(scale.get_value(5)); // print the average of 5 readings from the ADC minus the tare weight (not set yet)
Serial.print("get units: \t\t");
Serial.println(scale.get_units(5), 1); // print the average of 5 readings from the ADC minus tare weight (not set) divided
// by the SCALE parameter (not set yet)
scale.set_scale(-459.542);
//scale.set_scale(-471.497); // this value is obtained by calibrating the scale with known weights; see the README for details
scale.tare(); // reset the scale to 0
Serial.println("After setting up the scale:");
Serial.print("read: \t\t");
Serial.println(scale.read()); // print a raw reading from the ADC
Serial.print("read average: \t\t");
Serial.println(scale.read_average(20)); // print the average of 20 readings from the ADC
Serial.print("get value: \t\t");
Serial.println(scale.get_value(5)); // print the average of 5 readings from the ADC minus the tare weight, set with tare()
Serial.print("get units: \t\t");
Serial.println(scale.get_units(5), 1); // print the average of 5 readings from the ADC minus tare weight, divided
// by the SCALE parameter set with set_scale
Serial.println("Readings:");
}
void loop() {
Serial.print("one reading:\t");
Serial.print(scale.get_units(), 1);
Serial.print("\t| average:\t");
Serial.println(scale.get_units(10), 5);
delay(5000);
}
@awais110565
Connect like this:
