Create ISL29125_CCT.ino

LightSensors/ISL29125_CCT/ISL29125_CCT.ino

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+/*
+  ISL29125 light sensor with OLED display
+
+  Reads data from an ISL29125 light sensor and displays it on an SSD1306 OLED display.
+  Uses Sparkfun's SparkFunISL29125 library and Adafruit's Adafruit_SSD1306 library.
+
+  Sparkfun sensor library: https://github.com/sparkfun/SparkFun_ISL29125_Breakout_Arduino_Library
+  ISL29125 datasheet: https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/isl29125.pdf
+  Adafruit OLED library:
+  SSD1306 datasheet:
+
+  created 10 Feb 2020
+  by Tom Igoe
+*/
+
+#include <Wire.h>
+#include <SparkFunISL29125.h>
+
+// initialize light sensor:
+SFE_ISL29125 lightSensor;
+
+void setup() {
+  // initialize serial and wait for serial monitor to open:
+  Serial.begin(9600);
+  while (!Serial);
+
+  // if the light sensor doesn't initialize, quit:
+  if (!lightSensor.init()) {
+    Serial.println("Light sensor failed. Check wiring.");
+    return;
+  }
+}
+
+void loop() {
+
+  unsigned int red = lightSensor.readRed();
+  unsigned int green =  lightSensor.readGreen();
+  unsigned int blue =  lightSensor.readBlue();
+  unsigned int cct = calculateColorTemperature(red, green, blue);
+  unsigned int lux = calculateLux(red, green, blue);
+Serial.print(red);
+Serial.print("\t");
+Serial.print(green);
+Serial.print("\t");
+Serial.print(blue);
+Serial.print("\t");
+Serial.print(cct);
+Serial.print("\t");
+Serial.println(lux);
+  // take 2 seconds between readings:
+  delay(2000);
+}
+
+
+
+unsigned int calculateColorTemperature(unsigned int r, unsigned int g,
+                                       unsigned int b) {
+  float X, Y, Z; /* RGB to XYZ correlation      */
+  float xc, yc;  /* Chromaticity co-ordinates   */
+  float n;       /* McCamy's formula            */
+  float cct;
+
+  if (r == 0 && g == 0 && b == 0) {
+    return 0;
+  }
+
+  /* 1. Map RGB values to their XYZ counterparts.    */
+  /* Based on 6500K fluorescent, 3000K fluorescent   */
+  /* and 60W incandescent values for a wide range.   */
+  /* Note: Y = Illuminance or lux                    */
+  X = (-0.14282F * r) + (1.54924F * g) + (-0.95641F * b);
+  Y = (-0.32466F * r) + (1.57837F * g) + (-0.73191F * b);
+  Z = (-0.68202F * r) + (0.77073F * g) + (0.56332F * b);
+
+  /* 2. Calculate the chromaticity co-ordinates      */
+  xc = (X) / (X + Y + Z);
+  yc = (Y) / (X + Y + Z);
+
+  /* 3. Use McCamy's formula to determine the CCT    */
+  n = (xc - 0.3320F) / (0.1858F - yc);
+
+  /* Calculate the final CCT */
+  cct =
+    (449.0F * powf(n, 3)) + (3525.0F * powf(n, 2)) + (6823.3F * n) + 5520.33F;
+
+  /* Return the result  s in degrees Kelvin */
+  return (unsigned int)cct;
+}
+
+unsigned int calculateLux(unsigned int r, unsigned int g, unsigned int b) {
+  float illuminance;
+  illuminance = (-0.32466F * r) + (1.57837F * g) + (-0.73191F * b);
+
+  return (unsigned int)illuminance;
+}