Want to Master Air Pressure, Pressure & Level Control? This Module Works!

				
					#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED Configuration
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Manual HX710 reading (no external library)
#define HX710_SCK 3
#define HX710_DOUT 2

// Calibration parameters
float calibration_factor = 1.0;  // Needs adjustment via calibration
long zero_offset = 0;
const float SENSOR_MAX_PRESSURE = 40000.0;  // 40KPa
const long MAX_24BIT = 16777215L;  // 24-bit max value

// Water level calculation parameters
const float WATER_DENSITY = 1000.0;  // kg/m³
const float GRAVITY = 9.80665;       // m/s²

// Manual HX710 read function
long readHX710() {
  long count = 0;
  unsigned char data[3] = {0};
  
  // Wait for data ready
  while (digitalRead(HX710_DOUT) == HIGH) {
    delay(1);
  }
  
  // Read 24-bit data
  for (int i = 0; i < 24; i++) {
    digitalWrite(HX710_SCK, HIGH);
    delayMicroseconds(1);
    
    if (i < 24) {
      count = count << 1;
      digitalWrite(HX710_SCK, LOW);
      delayMicroseconds(1);
      
      if (digitalRead(HX710_DOUT)) {
        count++;
      }
    }
  }
  
  // 25th pulse to select next channel and gain
  digitalWrite(HX710_SCK, HIGH);
  delayMicroseconds(1);
  digitalWrite(HX710_SCK, LOW);
  delayMicroseconds(1);
  
  // Convert to signed value
  if (count & 0x800000) {
    count |= 0xFF000000;
  }
  
  return count;
}

// Get averaged reading
long getAverageReading(int times) {
  long sum = 0;
  for (int i = 0; i < times; i++) {
    sum += readHX710();
    delay(5);
  }
  return sum / times;
}

void setup() {
  Serial.begin(9600);
  
  // Initialize HX710 pins
  pinMode(HX710_SCK, OUTPUT);
  pinMode(HX710_DOUT, INPUT);
  digitalWrite(HX710_SCK, LOW);
  
  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("OLED initialization failed!"));
    while (1);
  }
  
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println(F("Water Level Monitor v1.0"));
  display.println(F("Initializing..."));
  display.display();
  delay(2000);
  
  // Warm up sensor
  delay(100);
  
  // Zero-point calibration
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println(F("Zero Calibration"));
  display.println(F("Ensure tube is dry"));
  display.println(F("Starting in 10s..."));
  display.display();
  delay(10000);
  
  zero_offset = getAverageReading(20);
  
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println(F("Calibration complete!"));
  display.println("Zero point: " + String(zero_offset));
  display.display();
  delay(2000);
  
  Serial.println("System ready");
  Serial.println("Zero offset: " + String(zero_offset));
}

void loop() {
  static unsigned long lastUpdate = 0;
  
  if (millis() - lastUpdate >= 1000) {  // Update every second
    long raw = getAverageReading(5);
    float calibrated_value = (raw - zero_offset) * calibration_factor;
    
    // Convert to pressure (Pa)
    float pressure_pa = calibrated_value * (SENSOR_MAX_PRESSURE / MAX_24BIT);
    
    // Convert to water level (cm), filter negative values
    float water_level_cm = 0;
    if (pressure_pa > 0) {
      float height_m = pressure_pa / (WATER_DENSITY * GRAVITY);
      water_level_cm = height_m * 100.0;
    }
    
    // Serial output
    Serial.print("Raw: ");
    Serial.print(raw);
    Serial.print(" | Calibrated: ");
    Serial.print(calibrated_value);
    Serial.print(" | Pressure: ");
    Serial.print(pressure_pa, 1);
    Serial.print(" Pa | Water Level: ");
    Serial.print(water_level_cm, 1);
    Serial.println(" cm");
    
    // OLED display
    updateDisplay(water_level_cm, pressure_pa, raw);
    
    lastUpdate = millis();
  }
}

void updateDisplay(float level_cm, float pressure_pa, long raw_value) {
  display.clearDisplay();
  
  // Title
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println(F("=== Water Level ==="));
  
  // Water level (large font)
  display.setTextSize(2);
  display.setCursor(0, 15);
  display.print(level_cm, 1);
  display.setTextSize(1);
  display.println(F(" cm"));
  
  // Pressure value
  display.setTextSize(1);
  display.setCursor(0, 35);
  display.print(F("Pressure: "));
  display.print(pressure_pa, 0);
  display.println(F(" Pa"));
  
  // Raw value
  display.setCursor(0, 45);
  display.print(F("Raw: "));
  display.print(raw_value);
  
  // Water level indicator bar
  int barHeight = constrain(map(level_cm, 0, 400, 0, 40), 0, 40);  // 0-400cm maps to 0-40 pixels
  display.fillRect(100, 24, 20, 40 - barHeight, SSD1306_BLACK);  // Clear upper part
  display.fillRect(100, 64 - barHeight, 20, barHeight, SSD1306_WHITE);  // Fill water level
  display.drawRect(100, 24, 20, 40, SSD1306_WHITE);  // Outline
  
  // Scale marks
  for (int i = 0; i <= 4; i++) {
    int y = 64 - (i * 10);
    display.drawFastHLine(95, y, 5, SSD1306_WHITE);
  }
  
  display.display();
}

// Serial calibration commands
void serialEvent() {
  if (Serial.available()) {
    char cmd = Serial.read();
    
    switch (cmd) {
      case 'z':  // Zero calibration
        zero_offset = getAverageReading(20);
        Serial.println("Zero calibration complete: " + String(zero_offset));
        break;
        
      case 'c':  // Set calibration factor
        Serial.println("Enter calibration factor: ");
        while (!Serial.available());
        calibration_factor = Serial.parseFloat();
        Serial.println("Calibration factor set to: " + String(calibration_factor));
        break;
        
      case 'h':  // Help
        Serial.println(F("Available commands:"));
        Serial.println(F("z - Zero calibration"));
        Serial.println(F("c - Set calibration factor"));
        Serial.println(F("h - Help"));
        break;
    }
  }
}