I am attempting to make a rocket test stand using a load cell and an hx711 board. I started with making some code and after that didn't work I looked at the library's example code and even tried other libraries.
HX711_ADC library GitHub - olkal/HX711_ADC: Arduino library for the HX711 24-bit ADC for weight scales
example code for HX711_ADC library
//-------------------------------------------------------------------------------------
// HX711_ADC.h
// Arduino master library for HX711 24-Bit Analog-to-Digital Converter for Weigh Scales
// Olav Kallhovd sept2017
// Tested with : HX711 asian module on channel A and YZC-133 3kg load cell
// Tested with MCU : Arduino Nano, ESP8266
//-------------------------------------------------------------------------------------
// This is an example sketch on how to use this library
// Settling time (number of samples) and data filtering can be adjusted in the config.h file
#include <HX711_ADC.h>
#include <EEPROM.h>
//HX711 constructor (dout pin, sck pin):
HX711_ADC LoadCell(4, 5);
const int eepromAdress = 0;
long t;
void setup() {
float calValue; // calibration value
calValue = 696.0; // uncomment this if you want to set this value in the sketch
#if defined(ESP8266)
//EEPROM.begin(512); // uncomment this if you use ESP8266 and want to fetch the value from eeprom
#endif
//EEPROM.get(eepromAdress, calValue); // uncomment this if you want to fetch the value from eeprom
Serial.begin(9600); delay(10);
Serial.println();
Serial.println("Starting...");
LoadCell.begin();
long stabilisingtime = 2000; // tare preciscion can be improved by adding a few seconds of stabilising time
LoadCell.start(stabilisingtime);
if(LoadCell.getTareTimeoutFlag()) {
Serial.println("Tare timeout, check MCU>HX711 wiring and pin designations");
}
else {
LoadCell.setCalFactor(calValue); // set calibration value (float)
Serial.println("Startup + tare is complete");
}
}
void loop() {
//update() should be called at least as often as HX711 sample rate; >10Hz@10SPS, >80Hz@80SPS
//use of delay in sketch will reduce effective sample rate (be carefull with use of delay() in the loop)
LoadCell.update();
//get smoothed value from data set
if (millis() > t + 250) {
float i = LoadCell.getData();
Serial.print("Load_cell output val: ");
Serial.println(i);
t = millis();
}
//receive from serial terminal
if (Serial.available() > 0) {
float i;
char inByte = Serial.read();
if (inByte == 't') LoadCell.tareNoDelay();
}
//check if last tare operation is complete
if (LoadCell.getTareStatus() == true) {
Serial.println("Tare complete");
}
}
the first example looks like this after running
Starting...
Startup + tare is complete
Load_cell output val: 0.00
Load_cell output val: 0.01
Load_cell output val: 0.02
Load_cell output val: 0.03
Load_cell output val: 0.03
Load_cell output val: 0.03
Load_cell output val: 0.01
Load_cell output val: -0.02
Load_cell output val: -0.07
Load_cell output val: -0.11
Load_cell output val: -0.14
Load_cell output val: -0.13
Load_cell output val: -0.08
Load_cell output val: 0.11
Load_cell output val: 0.45
Load_cell output val: 0.77
Load_cell output val: 1.39
and the values just keep changing without any weight on the load cell
HX711 library 2 GitHub - bogde/HX711: An Arduino library to interface the Avia Semiconductor HX711 24-Bit Analog-to-Digital Converter (ADC) for Weight Scales.
library 2 Sample code
/**
this is what the second example displays
HX711 Demo
Initializing the scale
Before setting up the scale:
read: -1235
read average: -1344
get value: -1351.00
get units: -1381.0
After setting up the scale:
read: -1353
read average: -1462
get value: 23.00
get units: 0.3
Readings:
one reading: 0.5 | average: 1.0
one reading: 0.1 | average: 0.0
one reading: 0.1 | average: 0.0
one reading: 0.1 | average: 0.0
one reading: 0.1 | average: 0.0
one reading: 0.1 | average: 0.0
one reading: 0.1 | average: 0.0
one reading: 0.0 | average: 0.0
one reading: 0.0 | average: 0.0
- HX711 library for Arduino - example file
- GitHub - bogde/HX711: An Arduino library to interface the Avia Semiconductor HX711 24-Bit Analog-to-Digital Converter (ADC) for Weight Scales.
- MIT License
- (c) 2018 Bogdan Necula
**/
#include "HX711.h"
// HX711 circuit wiring
const int LOADCELL_DOUT_PIN = 4;
const int LOADCELL_SCK_PIN = 5;
HX711 scale;
void setup() {
Serial.begin(9600);
Serial.println("HX711 Demo");
Serial.println("Initializing the scale");
// Initialize library with data output pin, clock input pin and gain factor.
// Channel selection is made by passing the appropriate gain:
// - With a gain factor of 64 or 128, channel A is selected
// - With a gain factor of 32, channel B is selected
// By omitting the gain factor parameter, the library
// default "128" (Channel A) is used here.
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(2280.f); // 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), 1);
scale.power_down(); // put the ADC in sleep mode
delay(1000);
scale.power_up();
}