I connected an Adafruit color sensor to my arduino and am having it make calculations. However, when the calculations are done and sent to the serial monitor, it says "NDVI: " without printing the value. The code is attached below. Thanks!

Code: /* TSL2591 Digital Light Sensor / / Dynamic Range: 600M:1 / / Maximum Lux: 88K */

#include <Wire.h> #include <Adafruit_Sensor.h> #include "Adafruit_TSL2591.h"

#define IR850 5 #define IR940 6 #define BLUE 9 #define GREEN 10 #define RED 11

// Example for demonstrating the TSL2591 library - public domain!

// connect SCL to I2C Clock // connect SDA to I2C Data // connect Vin to 3.3-5V DC // connect GROUND to common ground

Adafruit_TSL2591 tsl = Adafruit_TSL2591(2591); // pass in a number for the sensor identifier (for your use later)

// /* Displays some basic information on this sensor from the unified sensor API sensor_t type (see Adafruit_Sensor for more information) */ // void displaySensorDetails(void) { sensor_t sensor; tsl.getSensor(&sensor); Serial.println(F("------------------------------------")); Serial.print (F("Sensor: ")); Serial.println(sensor.name); Serial.print (F("Driver Ver: ")); Serial.println(sensor.version); Serial.print (F("Unique ID: ")); Serial.println(sensor.sensor_id); Serial.print (F("Max Value: ")); Serial.print(sensor.max_value); Serial.println(F(" lux")); Serial.print (F("Min Value: ")); Serial.print(sensor.min_value); Serial.println(F(" lux")); Serial.print (F("Resolution: ")); Serial.print(sensor.resolution, 4); Serial.println(F(" lux"));
Serial.println(F("------------------------------------")); Serial.println(F("")); delay(500); }

// /* Configures the gain and integration time for the TSL2591 */ // void configureSensor(void) { // You can change the gain on the fly, to adapt to brighter/dimmer light situations //tsl.setGain(TSL2591_GAIN_LOW); // 1x gain (bright light) //tsl.setGain(TSL2591_GAIN_MED); // 25x gain tsl.setGain(TSL2591_GAIN_HIGH); // 428x gain

// Changing the integration time gives you a longer time over which to sense light // longer timelines are slower, but are good in very low light situtations! //tsl.setTiming(TSL2591_INTEGRATIONTIME_100MS); // shortest integration time (bright light) // tsl.setTiming(TSL2591_INTEGRATIONTIME_200MS); // tsl.setTiming(TSL2591_INTEGRATIONTIME_300MS); // tsl.setTiming(TSL2591_INTEGRATIONTIME_400MS); // tsl.setTiming(TSL2591_INTEGRATIONTIME_500MS); tsl.setTiming(TSL2591_INTEGRATIONTIME_600MS); // longest integration time (dim light)

/* Display the gain and integration time for reference sake */
Serial.println(F("------------------------------------")); Serial.print (F("Gain: ")); tsl2591Gain_t gain = tsl.getGain(); switch(gain) { case TSL2591_GAIN_LOW: Serial.println(F("1x (Low)")); break; case TSL2591_GAIN_MED: Serial.println(F("25x (Medium)")); break; case TSL2591_GAIN_HIGH: Serial.println(F("428x (High)")); break; case TSL2591_GAIN_MAX: Serial.println(F("9876x (Max)")); break; } Serial.print (F("Timing: ")); Serial.print((tsl.getTiming() + 1) * 100, DEC); Serial.println(F(" ms")); Serial.println(F("------------------------------------")); Serial.println(F("")); }

// /* Program entry point for the Arduino sketch */ // void setup(void) { pinMode(IR850, OUTPUT); pinMode(IR940, OUTPUT); pinMode(RED, OUTPUT); pinMode(GREEN, OUTPUT); pinMode(BLUE, OUTPUT); digitalWrite(IR850, LOW); digitalWrite(IR940, LOW); digitalWrite(RED, LOW); digitalWrite(GREEN, LOW); digitalWrite(BLUE, LOW); Serial.begin(9600);

Serial.println(F("Starting Adafruit TSL2591 Test!"));

if (tsl.begin()) { Serial.println(F("Found a TSL2591 sensor")); } else { Serial.println(F("No sensor found ... check your wiring?")); while (1); }

/* Display some basic information on this sensor */ displaySensorDetails();

/* Configure the sensor */ configureSensor();

// Now we're ready to get readings ... move on to loop()! }

// /* Shows how to perform a basic read on visible, full spectrum or infrared light (returns raw 16-bit ADC values) */ // void simpleRead(void) { // Simple data read example. Just read the infrared, fullspecrtrum diode // or 'visible' (difference between the two) channels. // This can take 100-600 milliseconds! Uncomment whichever of the following you want to read uint16_t x = tsl.getLuminosity(TSL2591_VISIBLE); //uint16_t x = tsl.getLuminosity(TSL2591_FULLSPECTRUM); //uint16_t x = tsl.getLuminosity(TSL2591_INFRARED);

Serial.print(F("[ ")); Serial.print(millis()); Serial.print(F(" ms ] ")); Serial.print(F("Luminosity: ")); Serial.println(x, DEC); }

// /* Show how to read IR and Full Spectrum at once and convert to lux */ // uint16_t ir, full; void advancedRead(void) { // More advanced data read example. Read 32 bits with top 16 bits IR, bottom 16 bits full spectrum // That way you can do whatever math and comparisons you want! uint32_t lum = tsl.getFullLuminosity(); uint16_t ir, full; ir = lum >> 16; full = lum & 0xFFFF; Serial.print(F("[ ")); Serial.print(millis()); Serial.print(F(" ms ] ")); Serial.print(F("IR: ")); Serial.print(ir); Serial.print(F(" ")); Serial.print(F("Full: ")); Serial.print(full); Serial.print(F(" ")); Serial.print(F("Visible: ")); Serial.print(full - ir); Serial.print(F(" ")); Serial.print(F("Lux: ")); Serial.println(tsl.calculateLux(full, ir), 6); }

// /* Performs a read using the Adafruit Unified Sensor API. */ // void unifiedSensorAPIRead(void) { /* Get a new sensor event */ sensors_event_t event; tsl.getEvent(&event);

/* Display the results (light is measured in lux) / Serial.print(F("[ ")); Serial.print(event.timestamp); Serial.print(F(" ms ] ")); if ((event.light == 0) | (event.light > 4294966000.0) | (event.light <-4294966000.0)) { / If event.light = 0 lux the sensor is probably saturated / / and no reliable data could be generated! / / if event.light is +/- 4294967040 there was a float over/underflow */ Serial.println(F("Invalid data (adjust gain or timing)")); } else { Serial.print(event.light); Serial.println(F(" lux")); } }

int lightvalue; int NDVIred; int NDVIinfrared; int NDVI; boolean (hasrun) = false;

// /* Arduino loop function, called once 'setup' is complete (your own code should go here) */ // void loop(void) { lightvalue = 255; //simpleRead(); //advancedRead(); //unifiedSensorAPIRead(); if(hasrun==false){ analogWrite(RED, lightvalue); advancedRead(); NDVIred = full; delay(5000); analogWrite(IR940,lightvalue); advancedRead(); NDVIinfrared=full; NDVI=(NDVIinfrared-NDVIred)/(NDVIinfrared+NDVIred); Serial.print("NDVI: "); Serial.write(NDVIred); delay(1000); exit(0); } }

I connected an Adafruit color sensor to my Arduino and am having it make calculations. However, when the calculations are done and sent to the serial monitor, it says "NDVI: " without printing the value. The code is attached below. Thanks!

Code:

/* TSL2591 Digital Light Sensor */
/* Dynamic Range: 600M:1 */
/* Maximum Lux: 88K */

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_TSL2591.h"

#define IR850 5
#define IR940 6
#define BLUE 9
#define GREEN 10
#define RED 11

// Example for demonstrating the TSL2591 library - public domain!

// connect SCL to I2C Clock
// connect SDA to I2C Data
// connect Vin to 3.3-5V DC
// connect GROUND to common ground

Adafruit_TSL2591 tsl = Adafruit_TSL2591(2591); // pass in a number for the sensor identifier (for your use later)

/**************************************************************************/
/*
    Displays some basic information on this sensor from the unified
    sensor API sensor_t type (see Adafruit_Sensor for more information)
*/
/**************************************************************************/
void displaySensorDetails(void)
{
  sensor_t sensor;
  tsl.getSensor(&sensor);
  Serial.println(F("------------------------------------"));
  Serial.print  (F("Sensor:       ")); Serial.println(sensor.name);
  Serial.print  (F("Driver Ver:   ")); Serial.println(sensor.version);
  Serial.print  (F("Unique ID:    ")); Serial.println(sensor.sensor_id);
  Serial.print  (F("Max Value:    ")); Serial.print(sensor.max_value); Serial.println(F(" lux"));
  Serial.print  (F("Min Value:    ")); Serial.print(sensor.min_value); Serial.println(F(" lux"));
  Serial.print  (F("Resolution:   ")); Serial.print(sensor.resolution, 4); Serial.println(F(" lux"));  
  Serial.println(F("------------------------------------"));
  Serial.println(F(""));
  delay(500);
}

/**************************************************************************/
/*
    Configures the gain and integration time for the TSL2591
*/
/**************************************************************************/
void configureSensor(void)
{
  // You can change the gain on the fly, to adapt to brighter/dimmer light situations
  //tsl.setGain(TSL2591_GAIN_LOW);    // 1x gain (bright light)
  //tsl.setGain(TSL2591_GAIN_MED);      // 25x gain
  tsl.setGain(TSL2591_GAIN_HIGH);   // 428x gain
  
  // Changing the integration time gives you a longer time over which to sense light
  // longer timelines are slower, but are good in very low light situtations!
  //tsl.setTiming(TSL2591_INTEGRATIONTIME_100MS);  // shortest integration time (bright light)
  // tsl.setTiming(TSL2591_INTEGRATIONTIME_200MS);
  // tsl.setTiming(TSL2591_INTEGRATIONTIME_300MS);
  // tsl.setTiming(TSL2591_INTEGRATIONTIME_400MS);
  // tsl.setTiming(TSL2591_INTEGRATIONTIME_500MS);
  tsl.setTiming(TSL2591_INTEGRATIONTIME_600MS);  // longest integration time (dim light)

  /* Display the gain and integration time for reference sake */  
  Serial.println(F("------------------------------------"));
  Serial.print  (F("Gain:         "));
  tsl2591Gain_t gain = tsl.getGain();
  switch(gain)
  {
    case TSL2591_GAIN_LOW:
      Serial.println(F("1x (Low)"));
      break;
    case TSL2591_GAIN_MED:
      Serial.println(F("25x (Medium)"));
      break;
    case TSL2591_GAIN_HIGH:
      Serial.println(F("428x (High)"));
      break;
    case TSL2591_GAIN_MAX:
      Serial.println(F("9876x (Max)"));
      break;
  }
  Serial.print  (F("Timing:       "));
  Serial.print((tsl.getTiming() + 1) * 100, DEC); 
  Serial.println(F(" ms"));
  Serial.println(F("------------------------------------"));
  Serial.println(F(""));
}


/**************************************************************************/
/*
    Program entry point for the Arduino sketch
*/
/**************************************************************************/
void setup(void) 
{
  pinMode(IR850, OUTPUT);
  pinMode(IR940, OUTPUT);
  pinMode(RED, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(BLUE, OUTPUT);
  digitalWrite(IR850, LOW);
  digitalWrite(IR940, LOW);
  digitalWrite(RED, LOW);
  digitalWrite(GREEN, LOW);
  digitalWrite(BLUE, LOW);
  Serial.begin(9600);

  Serial.println(F("Starting Adafruit TSL2591 Test!"));
  
  if (tsl.begin()) 
  {
    Serial.println(F("Found a TSL2591 sensor"));
  } 
  else 
  {
    Serial.println(F("No sensor found ... check your wiring?"));
    while (1);
  }
    
  /* Display some basic information on this sensor */
  displaySensorDetails();
  
  /* Configure the sensor */
  configureSensor();

  

  // Now we're ready to get readings ... move on to loop()!
}

/**************************************************************************/
/*
    Shows how to perform a basic read on visible, full spectrum or
    infrared light (returns raw 16-bit ADC values)
*/
/**************************************************************************/
void simpleRead(void)
{
  // Simple data read example. Just read the infrared, fullspecrtrum diode 
  // or 'visible' (difference between the two) channels.
  // This can take 100-600 milliseconds! Uncomment whichever of the following you want to read
  uint16_t x = tsl.getLuminosity(TSL2591_VISIBLE);
  //uint16_t x = tsl.getLuminosity(TSL2591_FULLSPECTRUM);
  //uint16_t x = tsl.getLuminosity(TSL2591_INFRARED);

  Serial.print(F("[ ")); Serial.print(millis()); Serial.print(F(" ms ] "));
  Serial.print(F("Luminosity: "));
  Serial.println(x, DEC);
}

/**************************************************************************/
/*
    Show how to read IR and Full Spectrum at once and convert to lux
*/
/**************************************************************************/
uint16_t ir, full;
void advancedRead(void)
{
  // More advanced data read example. Read 32 bits with top 16 bits IR, bottom 16 bits full spectrum
  // That way you can do whatever math and comparisons you want!
  uint32_t lum = tsl.getFullLuminosity();
  uint16_t ir, full;
  ir = lum >> 16;
  full = lum & 0xFFFF;
  Serial.print(F("[ ")); Serial.print(millis()); Serial.print(F(" ms ] "));
  Serial.print(F("IR: ")); Serial.print(ir);  Serial.print(F("  "));
  Serial.print(F("Full: ")); Serial.print(full); Serial.print(F("  "));
  Serial.print(F("Visible: ")); Serial.print(full - ir); Serial.print(F("  "));
  Serial.print(F("Lux: ")); Serial.println(tsl.calculateLux(full, ir), 6);
}

/**************************************************************************/
/*
    Performs a read using the Adafruit Unified Sensor API.
*/
/**************************************************************************/
void unifiedSensorAPIRead(void)
{
  /* Get a new sensor event */ 
  sensors_event_t event;
  tsl.getEvent(&event);
 
  /* Display the results (light is measured in lux) */
  Serial.print(F("[ ")); Serial.print(event.timestamp); Serial.print(F(" ms ] "));
  if ((event.light == 0) |
      (event.light > 4294966000.0) | 
      (event.light <-4294966000.0))
  {
    /* If event.light = 0 lux the sensor is probably saturated */
    /* and no reliable data could be generated! */
    /* if event.light is +/- 4294967040 there was a float over/underflow */
    Serial.println(F("Invalid data (adjust gain or timing)"));
  }
  else
  {
    Serial.print(event.light); Serial.println(F(" lux"));
  }
}

int lightvalue;
int NDVIred;
int NDVIinfrared;
int NDVI;
boolean (hasrun) = false;

/**************************************************************************/
/*
    Arduino loop function, called once 'setup' is complete (your own code
    should go here)
*/
/**************************************************************************/
void loop(void)
{ 
  lightvalue = 255;
  //simpleRead(); 
  //advancedRead();
  //unifiedSensorAPIRead();
  if(hasrun==false){
  analogWrite(RED, lightvalue);
  advancedRead();
  NDVIred = full;
  delay(5000);
  analogWrite(IR940,lightvalue);
  advancedRead();
  NDVIinfrared=full;
  NDVI=(NDVIinfrared-NDVIred)/(NDVIinfrared+NDVIred);
  Serial.print("NDVI: "); Serial.write(NDVIred);
  delay(1000);
  exit(0);
  }
}