Example Code for Arduino-UV Intensity Reading

Hardware Preparation

• Arduino Board (Uno/Leonardo/Mega), Quantity: 1
• UV Sensor v1.0-ML8511 (SEN0175), Quantity: 1, Purchase Link: https://www.dfrobot.com/product-1195.html

Software Preparation

• Development Tool: Arduino IDE, Download Link: https://www.arduino.cc/en/software
• No additional libraries are required.

Wiring Diagram

Other Preparation Work

1. Connect ML8511 UV Sensor to Arduino A0.
2. This code is tested on Arduino Uno, Leonardo, Mega boards.
3. Open Arduino IDE, select the correct board and port in Tools menu.

Sample Code

/***************************************************
 * UV Sensor v1.0-ML8511
 * <https://www.dfrobot.com/index.php?route=product/product&product_id=1195&search=uv&description=true>
 ***************************************************
 * This example reads UV intensity from UV Sensor v1.0-ML8511.
 *
 * Created 2014-9-23
 * By Phoebe <[email protected]>
 * Modified 2014-9-23
 * By Phoebe [email protected]>
 *
 * GNU Lesser General Public License.
 * See <http://www.gnu.org/licenses/> for details.
 * All above must be included in any redistribution
 ****************************************************/

/***********Notice and Trouble shooting***************
 * 1.Connect ML8511 UV Sensor to Arduino A0
   <https://www.dfrobot.com/wiki/index.php/File:SEN0175_Diagram.png>
 * 2.This code is tested on Arduino Uno, Leonardo, Mega boards.
 ****************************************************/


int ReadUVintensityPin = A0; //Output from the sensor

void setup()
{
  pinMode(ReadUVintensityPin, INPUT);
  Serial.begin(9600); //open serial port, set the baud rate to 9600 bps
  Serial.println("Starting up...");
}

void loop()
{
  int uvLevel = averageAnalogRead(ReadUVintensityPin);

  float outputVoltage = 5.0 * uvLevel/1024;
  float uvIntensity = mapfloat(outputVoltage, 0.99, 2.9, 0.0, 15.0);

  Serial.print("UVAnalogOutput: ");
  Serial.print(uvLevel);

  Serial.print(" OutputVoltage: ");
  Serial.print(outputVoltage);

  Serial.print(" UV Intensity: ");
  Serial.print(uvIntensity);
  Serial.print(" mW/cm^2");

  Serial.println();
  delay(100);
}

//Takes an average of readings on a given pin
//Returns the average
int averageAnalogRead(int pinToRead)
{
  byte numberOfReadings = 8;
  unsigned int runningValue = 0;

  for(int x = 0 ; x < numberOfReadings ; x++)
    runningValue += analogRead(pinToRead);
  runningValue /= numberOfReadings;

  return(runningValue);

}

//The Arduino Map function but for floats
//From: http://forum.arduino.cc/index.php?topic=3922.0
float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

Result

Open the Arduino Serial Monitor (baud rate: 9600) to view the output. The serial monitor will display messages like:

UVAnalogOutput: [value] OutputVoltage: [value] UV Intensity: [value] mW/cm^2

Additional Information

Mapping the outputVoltage to intensity is straight forward. No UV light starts at 1V with a maximum of 15mW/cm2 at around 2.8V. Arduino has a built-in map() function, but map() does not work for floats. Thanks to users on the Arduino forum, we have a simple mapFloat() function:

//The Arduino Map function but for floats
//From: http://forum.arduino.cc/index.php?topic=3922.0
float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

The following line converts the voltage read from the sensor to mW/cm2 intensity:

float uvIntensity = mapfloat(outputVoltage, 0.99, 2.8, 0.0, 15.0); //Convert the voltage to a UV intensity level