Using the ML8511 UV Sensor Without a Library

Projects Programming
1

I learned about the ML8511 UV sensor from a tutorial, but the code provided didn’t include a library. Is it okay to use it that way, or should we include a library?

UV index meter interfacing Arduino or ESP32 with ML8511 – Circuit Schools

Using The UV Ray Detection Module GY-ML8511 with Arduino - Phipps Electronics

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
 
int UVOUT = 15; //Output from the sensor
int REF_3V3 = 4; //3.3V power on the ESP32 board

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

void setup()
{
  Serial.begin(9600);
  pinMode(UVOUT, INPUT);
  pinMode(REF_3V3, INPUT);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //initialize with the I2C addr 0x3C (128x64)
  display.clearDisplay();
  }
 
//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);
}
 
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;
}
 
void loop()
{
  int uvLevel = averageAnalogRead(UVOUT);
  int refLevel = averageAnalogRead(REF_3V3);
  
  //Use the 3.3V power pin as a reference to get a very accurate output value from sensor
  float outputVoltage = 3.3 / refLevel * uvLevel;
  
  float uvIntensity = mapfloat(outputVoltage, 0.99, 2.8, 0.0, 15.0); //Convert the voltage to a UV intensity level
 
  Serial.print("output: ");
  Serial.print(refLevel);
 
  Serial.print("ML8511 output: ");
  Serial.print(uvLevel);
 
  Serial.print(" / ML8511 voltage: ");
  Serial.print(outputVoltage);
 
  Serial.print(" / UV Intensity (mW/cm^2): ");
  Serial.print(uvIntensity);
  Serial.println(); 
  display.setCursor(20,0);  //oled display
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.println("UV Ray Intensity");
  
  display.setCursor(20,20);  //oled display
  display.setTextSize(3);
  display.setTextColor(WHITE);
  display.println(uvIntensity);
  
  display.setCursor(20,45);  //oled display
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.println("mW/cm^2");
  display.display();
  delay(300);
  display.clearDisplay();
}
2

You do not need a library for everything.

In this case the sensor just returns an analogue value, so wiring it to an analogue input is just fine.

From that tutorial it says:-

The ML8511 module from Lapis Semiconductor Co Ltd is an ultraviolet (UV) light sensor, that delivers an analog signal that depends on the amount of UV light it detects. It is used in projects to monitor environmental conditions such as the UV index.

The analog output is linearly related to UV intensity (mW / cm2). This analog signal can be connected to a microcontroller which is capable of converting analog to voltage conversions to detect the level of UV.

1 Like
3

If the code works, use it.

Using libraries for sensors is not mandatory, but can make things easier for beginners, especially for more complex sensors. The library hides the complex code. Libraries cannot perform any special functions that cannot also be performed by your own code.

4

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