This is my first post and I am an absolute beginner at all this. So please forgive me if I don’t give enough information to describe my problem. I want to build a scale using four 50kg load cells with an HX711 amplifier going to a (genuine) Arduino Uno. Actually, I have the prototype scale build and wired up ready to test. For the display, I have a 128 X 32 OLED hooked up. I want to power this with a 9v battery eventually. This scale will always have the weight on it and I want to power it up once per day to check for additional weight and then power it off. So I need the weight saved into the board’s memory at power down. I found this main sketch that I believe is supposed to meet my needs. Only problem is it doesn’t work. I can verify the sketch with no problems. It also uploads fine with no issues. When I open the serial monitor it prints “starting… startup complete”. The OLED displays my personalized startup message “watermelons 2023” and “Initializing” below that but that is all. It just stops at that point. I then decided to try the calibration sketch in the HX711_ADC (library). It loaded fine and I was able to calibrate the scale no problems. I changed the calibration factor so that it was actually a very accurate scale in a variety of weights. So I believe that tells me that the wiring and loads cells are good. I know very little about code so I was hoping someone could take a look at it to see if something stands out. First I will add a pic of how I wired it up. The OLED wires are grd to grd, VCC to 5V, DT to pin 4, SCK to pin 5.
#include <HX711_ADC.h>
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <U8g2lib.h>
#if defined(ESP8266) || defined(ESP32) || defined(AVR)
#include <EEPROM.h>
#endif
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 32 // OLED display height, in pixels
#define Y_POS_0 0
#define X_POS_0 0
#define Y_POS_10 10
#define X_POS_10 10
#define TEXT_SIZE_SMALL 1
#define TEXT_SIZE_MED 2
#define TEXT_SIZE_LARGE 3
#define LONG_DELAY 4000
#define MED_DELAY 2000
#define SHORT_DELAY 1000
#define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
//pins:
//OLED USES I2C -> ON ARDUINO UNO: SCL @ A5, SDA @ A4
const int HX711_dout = 4; //mcu > HX711 dout pin
const int HX711_sck = 5; //mcu > HX711 sck pin
//HX711 constructor:
HX711_ADC LoadCell(HX711_dout, HX711_sck);
const int calVal_eepromAdress = 0;
const int tareOffsetVal_eepromAdress = 4;
unsigned long t = 0;
void setup() {
Serial.begin(57600);
delay(10);
Serial.println();
Serial.println("Starting...");
//SETUP LOAD CELLS
LoadCell.begin();
//LoadCell.setReverseOutput();
float calibrationValue;
20.9 // calibration value (see example file "Calibration.ino")
#if defined(ESP8266) || defined(ESP32)
EEPROM.begin(512);
#endif
;
EEPROM.get(calVal_eepromAdress, calibrationValue); // uncomment this if you want to fetch the calibration value from eeprom
//restore the zero offset value from eeprom:
long tare_offset = 0;
EEPROM.get(tareOffsetVal_eepromAdress, tare_offset);
LoadCell.setTareOffset(tare_offset);
unsigned long stabilizingtime = 2000; // preciscion right after power-up can be improved by adding a few seconds of stabilizing time
LoadCell.start(stabilizingtime, false);
if (LoadCell.getTareTimeoutFlag()) {
Serial.println("Timeout, check MCU>HX711 wiring and pin designations");
while (1)
;
} else {
LoadCell.setCalFactor(calibrationValue); // set calibration value (float)
Serial.println("Startup is complete");
}
//SETUP OLED
// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
Serial.println(F("SSD1306 allocation failed"));
for (;;)
; // Don't proceed, loop forever
}
// Clear the buffer
display.clearDisplay();
// Draw a single pixel in white
display.clearDisplay();
display.setTextSize(TEXT_SIZE_SMALL);
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(Y_POS_0, X_POS_0); // Start at top-left corner
display.println("watermelons 2023"); //customize your own start screen message
display.println("\nInitializing");
display.display();
delay(LONG_DELAY);
}
void setDisplayParameters(int cursorPosY, int cursorPosX, int textSize) {
display.clearDisplay();
display.setTextSize(textSize);
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(cursorPosY, cursorPosX); // Starting point of display
}
void displayWeightInKGs(float weightInGrams, int cursorPosY, int cursorPosX, int size, int delayTime) {
setDisplayParameters(cursorPosY, cursorPosX, size);
float weight = weightInGrams / 1000;
if (weight < 0) {
weight = 0.00;
}
String weightInKGs = String(weight);
display.println(weightInKGs);
display.display();
delay(delayTime);
}
void loop() {
//GET VALUES FROM LOAD CELLS
float value = 0.0;
static boolean newDataReady = 0;
const int serialPrintInterval = 250; //increase value to slow down serial print activity
// check for new data/start next conversion:
if (LoadCell.update()) {
newDataReady = true;
}
// get smoothed value from the dataset:
if (newDataReady) {
if (millis() > t + serialPrintInterval) {
float value = LoadCell.getData();
Serial.print("Load_cell output val: ");
Serial.println(value);
//DISPLAY VALUE ON THE OLED
displayWeightInKGs(value, Y_POS_10, X_POS_10, TEXT_SIZE_LARGE, SHORT_DELAY);
newDataReady = 0;
t = millis();
}
}
}
