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Adafruit_TCS34725.cpp

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+/**************************************************************************/
+/*!
+    @file     Adafruit_TCS34725.cpp
+    @author   KTOWN (Adafruit Industries)
+    @license  BSD (see license.txt)
+
+    Driver for the TCS34725 digital color sensors.
+
+    Adafruit invests time and resources providing this open source code,
+    please support Adafruit and open-source hardware by purchasing
+    products from Adafruit!
+
+    @section  HISTORY
+
+    v1.0 - First release
+*/
+/**************************************************************************/
+#include <avr/pgmspace.h>
+#include <util/delay.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "Adafruit_TCS34725.h"
+
+/*========================================================================*/
+/*                          PRIVATE FUNCTIONS                             */
+/*========================================================================*/
+
+/**************************************************************************/
+/*!
+    @brief  Implements missing powf function
+*/
+/**************************************************************************/
+float powf(const float x, const float y)
+{
+  return (float)(pow((double)x, (double)y));
+}
+
+/**************************************************************************/
+/*!
+    @brief  Writes a register and an 8 bit value over I2C
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::write8 (uint8_t reg, uint32_t value)
+{
+  Wire.beginTransmission(TCS34725_ADDRESS);
+  #if ARDUINO >= 100
+  Wire.write(TCS34725_COMMAND_BIT | reg);
+  Wire.write(value & 0xFF);
+  #else
+  Wire.send(TCS34725_COMMAND_BIT | reg);
+  Wire.send(value & 0xFF);
+  #endif
+  Wire.endTransmission();
+}
+
+/**************************************************************************/
+/*!
+    @brief  Reads an 8 bit value over I2C
+*/
+/**************************************************************************/
+uint8_t Adafruit_TCS34725::read8(uint8_t reg)
+{
+  Wire.beginTransmission(TCS34725_ADDRESS);
+  #if ARDUINO >= 100
+  Wire.write(TCS34725_COMMAND_BIT | reg);
+  #else
+  Wire.send(TCS34725_COMMAND_BIT | reg);
+  #endif
+  Wire.endTransmission();
+
+  Wire.requestFrom(TCS34725_ADDRESS, 1);
+  #if ARDUINO >= 100
+  return Wire.read();
+  #else
+  return Wire.receive();
+  #endif
+}
+
+/**************************************************************************/
+/*!
+    @brief  Reads a 16 bit values over I2C
+*/
+/**************************************************************************/
+uint16_t Adafruit_TCS34725::read16(uint8_t reg)
+{
+  uint16_t x; uint16_t t;
+
+  Wire.beginTransmission(TCS34725_ADDRESS);
+  #if ARDUINO >= 100
+  Wire.write(TCS34725_COMMAND_BIT | reg);
+  #else
+  Wire.send(TCS34725_COMMAND_BIT | reg);
+  #endif
+  Wire.endTransmission();
+
+  Wire.requestFrom(TCS34725_ADDRESS, 2);
+  #if ARDUINO >= 100
+  t = Wire.read();
+  x = Wire.read();
+  #else
+  t = Wire.receive();
+  x = Wire.receive();
+  #endif
+  x <<= 8;
+  x |= t;
+  return x;
+}
+
+/**************************************************************************/
+/*!
+    Enables the device
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::enable(void)
+{
+  write8(TCS34725_ENABLE, TCS34725_ENABLE_PON);
+  delay(3);
+  write8(TCS34725_ENABLE, TCS34725_ENABLE_PON | TCS34725_ENABLE_AEN);  
+}
+
+/**************************************************************************/
+/*!
+    Disables the device (putting it in lower power sleep mode)
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::disable(void)
+{
+  /* Turn the device off to save power */
+  uint8_t reg = 0;
+  reg = read8(TCS34725_ENABLE);
+  write8(TCS34725_ENABLE, reg & ~(TCS34725_ENABLE_PON | TCS34725_ENABLE_AEN));
+}
+
+/*========================================================================*/
+/*                            CONSTRUCTORS                                */
+/*========================================================================*/
+
+/**************************************************************************/
+/*!
+    Constructor
+*/
+/**************************************************************************/
+Adafruit_TCS34725::Adafruit_TCS34725(tcs34725IntegrationTime_t it, tcs34725Gain_t gain) 
+{
+  _tcs34725Initialised = false;
+  _tcs34725IntegrationTime = it;
+  _tcs34725Gain = gain;
+}
+
+/*========================================================================*/
+/*                           PUBLIC FUNCTIONS                             */
+/*========================================================================*/
+
+/**************************************************************************/
+/*!
+    Initializes I2C and configures the sensor (call this function before
+    doing anything else)
+*/
+/**************************************************************************/
+boolean Adafruit_TCS34725::begin(void) 
+{
+  Wire.begin();
+
+  /* Make sure we're actually connected */
+  uint8_t x = read8(TCS34725_ID);
+  Serial.println(x, HEX);
+  if (x != 0x44)
+  {
+    return false;
+  }
+  _tcs34725Initialised = true;
+
+  /* Set default integration time and gain */
+  setIntegrationTime(_tcs34725IntegrationTime);
+  setGain(_tcs34725Gain);
+
+  /* Note: by default, the device is in power down mode on bootup */
+  enable();
+
+  return true;
+}
+
+/**************************************************************************/
+/*!
+    Sets the integration time for the TC34725
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::setIntegrationTime(tcs34725IntegrationTime_t it)
+{
+  if (!_tcs34725Initialised) begin();
+
+  /* Update the timing register */
+  write8(TCS34725_ATIME, it);
+
+  /* Update value placeholders */
+  _tcs34725IntegrationTime = it;
+}
+
+/**************************************************************************/
+/*!
+    Adjusts the gain on the TCS34725 (adjusts the sensitivity to light)
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::setGain(tcs34725Gain_t gain)
+{
+  if (!_tcs34725Initialised) begin();
+
+  /* Update the timing register */
+  write8(TCS34725_CONTROL, gain);
+
+  /* Update value placeholders */
+  _tcs34725Gain = gain;
+}
+
+/**************************************************************************/
+/*!
+    @brief  Reads the raw red, green, blue and clear channel values
+*/
+/**************************************************************************/
+void Adafruit_TCS34725::getRawData (uint16_t *r, uint16_t *g, uint16_t *b, uint16_t *c)
+{
+  if (!_tcs34725Initialised) begin();
+
+  *c = read16(TCS34725_CDATAL);
+  *r = read16(TCS34725_RDATAL);
+  *g = read16(TCS34725_GDATAL);
+  *b = read16(TCS34725_BDATAL);
+
+  /* Set a delay for the integration time */
+  switch (_tcs34725IntegrationTime)
+  {
+    case TCS34725_INTEGRATIONTIME_2_4MS:
+      delay(3);
+      break;
+    case TCS34725_INTEGRATIONTIME_24MS:
+      delay(24);
+      break;
+    case TCS34725_INTEGRATIONTIME_101MS:
+      delay(101);
+      break;
+    case TCS34725_INTEGRATIONTIME_154MS:
+      delay(154);
+      break;
+    case TCS34725_INTEGRATIONTIME_700MS:
+      delay(700);
+      break;
+  }
+}
+
+/**************************************************************************/
+/*!
+    @brief  Converts the raw R/G/B values to color temperature in degrees
+            Kelvin
+*/
+/**************************************************************************/
+uint16_t Adafruit_TCS34725::calculateColorTemperature(uint16_t r, uint16_t g, uint16_t b)
+{
+  float X, Y, Z;      /* RGB to XYZ correlation      */
+  float xc, yc;       /* Chromaticity co-ordinates   */
+  float n;            /* McCamy's formula            */
+  float cct;
+
+  /* 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 results in degrees Kelvin */
+  return (uint16_t)cct;
+}
+
+/**************************************************************************/
+/*!
+    @brief  Converts the raw R/G/B values to color temperature in degrees
+            Kelvin
+*/
+/**************************************************************************/
+uint16_t Adafruit_TCS34725::calculateLux(uint16_t r, uint16_t g, uint16_t b)
+{
+  float illuminance;
+
+  /* This only uses RGB ... how can we integrate clear or calculate lux */
+  /* based exclusively on clear since this might be more reliable?      */
+  illuminance = (-0.32466F * r) + (1.57837F * g) + (-0.73191F * b);
+
+  return (uint16_t)illuminance;
+}