Nir Sensor

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_AS7343.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>


// Forward declarations
void setIndicator(bool green, bool yellow, bool red);
void showLines(const String &line1, const String &line2, const String &line3, const String &line4);
bool readSpectrum(uint16_t readings[18]);
float spectralDifference(const uint16_t sample[18]);
void saveAutomaticBaseline();

constexpr int I2C_SDA_PIN = 8;
constexpr int I2C_SCL_PIN = 9;
constexpr int LED_GREEN_PIN = 1;
constexpr int LED_YELLOW_PIN = 2;
constexpr int LED_RED_PIN = 3;
constexpr uint8_t OLED_ADDRESS = 0x3C;
constexpr int SCREEN_WIDTH = 128;
constexpr int SCREEN_HEIGHT = 64;
constexpr unsigned long BASELINE_WAIT_MS = 5000;
constexpr unsigned long SAMPLE_INTERVAL_MS = 800;
constexpr float MIN_SIGNAL = 20.0f;

Adafruit_AS7343 spectralSensor;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
uint16_t baseline[14] = {0};
bool baselineSaved = false;
unsigned long startedMs = 0;
unsigned long lastSampleMs = 0;
String previousScreen = "";

void setIndicator(bool green, bool yellow, bool red) {
  digitalWrite(LED_GREEN_PIN, green ? HIGH : LOW);
  digitalWrite(LED_YELLOW_PIN, yellow ? HIGH : LOW);
  digitalWrite(LED_RED_PIN, red ? HIGH : LOW);
}

void showLines(const String &line1, const String &line2, const String &line3, const String &line4) {
  String screen = line1 + "\n" + line2 + "\n" + line3 + "\n" + line4;
  if (screen == previousScreen) return;
  previousScreen = screen;
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0); display.println(line1);
  display.setCursor(0, 16); display.println(line2);
  display.setCursor(0, 30); display.println(line3);
  display.setCursor(0, 44); display.println(line4);
  display.display();
}

bool readSpectrum(uint16_t readings[18]) {
  return spectralSensor.readAllChannels(readings);
}

float spectralDifference(const uint16_t sample[18]) {
  float sum = 0.0f;
  for (int i = 0; i < 14; i++) {
    float divisor = baseline[i] > MIN_SIGNAL ? baseline[i] : MIN_SIGNAL;
    float change = (static_cast<float>(sample[i]) - baseline[i]) / divisor;
    sum += change * change;
  }
  return sqrtf(sum / 14.0f) * 100.0f;
}

void saveAutomaticBaseline() {
  uint16_t reading[18] = {0};
  if (!readSpectrum(reading)) {
    showLines("Read failed", "Check AS7343 wires", "SDA GPIO8", "SCL GPIO9");
    setIndicator(false, true, false);
    return;
  }
  for (int i = 0; i < 14; i++) baseline[i] = reading[i];
  baselineSaved = true;
  setIndicator(true, false, false);
  showLines("Reference saved", "Clean water stored", "Insert sample", "Green = similar");
  Serial.println("Automatic clean-water reference saved.");
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_GREEN_PIN, OUTPUT);
  pinMode(LED_YELLOW_PIN, OUTPUT);
  pinMode(LED_RED_PIN, OUTPUT);
  setIndicator(false, false, false);

  Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    while (true) delay(100);
  }
  showLines("Microplastic scan", "Starting AS7343...", "Put clean water in", "the dark chamber");

  if (!spectralSensor.begin(0x39, &Wire)) {
    showLines("Sensor not found", "Check AS7343 wires", "SDA GPIO8", "SCL GPIO9");
    setIndicator(false, false, true);
    while (true) delay(100);
  }
  startedMs = millis();
  showLines("Ready to calibrate", "Keep clean water", "in the chamber", "Wait 5 seconds");
}

void loop() {
  if (!baselineSaved) {
    unsigned long elapsed = millis() - startedMs;
    if (elapsed >= BASELINE_WAIT_MS) {
      saveAutomaticBaseline();
    } else {
      unsigned long secondsLeft = (BASELINE_WAIT_MS - elapsed + 999) / 1000;
      showLines("Calibrating soon", "Clean water in place", "Wait " + String(secondsLeft) + " seconds", "No button needed");
    }
    return;
  }

  if (millis() - lastSampleMs < SAMPLE_INTERVAL_MS) return;
  lastSampleMs = millis();

  uint16_t sample[18] = {0};
  if (!readSpectrum(sample)) {
    setIndicator(false, true, false);
    showLines("Read failed", "Keep sensor still", "Check I2C wires", "Try again");
    return;
  }

  float difference = spectralDifference(sample);
  String result;
  if (difference < 12.0f) {
    result = "Similar";
    setIndicator(true, false, false);
  } else if (difference < 30.0f) {
    result = "Changed: recheck";
    setIndicator(false, true, false);
  } else {
    result = "Strong change";
    setIndicator(false, false, true);
  }

  String differenceText = String(difference, 1) + "%";
  showLines("NIR screening only", result, "Difference: " + differenceText, "G/Y/R status light");
  Serial.printf("difference=%.2f%%, F1=%u, NIR=%u, result=%s\n", difference, sample[0], sample[3], result.c_str());
}