Published December 8, 2024

UV lamp, self activation, based on UV level.

UV lamps help tremendously with growing plants. Pair that with a UV sensor to prevent overusing the lamp, and you can grow anything you want

BeginnerShowcase (no instructions)6 hours66

UV lamp, self activation, based on UV level.

Things used in this project

Hardware components

Arduino UNO

Jumper wires (generic)

hanging lamp

uv bulb

Hitec RCD 31425S HS-425BB Pro BB Servo

waveshare Digital LTR390-UV Ultraviolet Sensor (C)

Software apps and online services

Arduino IoT Cloud

Story

My journey with this project began after taking an aquaponics class, which sparked a new passion for growing plants. I quickly realized that my room didn’t get enough natural UV light for my plants to grow properly. After talking to some experienced friends in the plant-growing community, I learned about UV lamps. However, I soon noticed that the bulbs in my UV lamp would burn out every few months, requiring constant replacement. That's when I came up with the idea of making the lamp more efficient by only turning it on when the UV light available for the plants was insufficient for their growth or survival.

While this design is still quite basic and may not be the most aesthetically pleasing, it works well, is simple, and is relatively cost-efficient—especially if you already have a lamp. Putting this system together took just a few hours over the course of a few days. Most of the time was spent trying to get it working with a Photon 2, which unfortunately didn't have the necessary libraries, so I switched to using an Arduino. Bellow I will post a photo of a possible application on a desk and a video of the concept working.

application on desk

When Sensor gets light light is off

When sensor does not get light lamp off

https://drive.google.com/file/d/1NRETVAYQve2j0qx8OO04ghGXl5P5JhJN/view?usp=sharing (link of video)

Schematics

UV sensor wiring, and servo wiring.

I have broken it down into two photos where the wires for one of the two components are on the Arduino. On the left side, you will need 4 jumper wires that have one female and one male end to connect with the Arduino. I have color-coded the wires and labeled them. Purple will go to 3.3V, orange to GND, yellow to SCL, and blue to SDA. This will connect your Arduino to the UV sensor. For the right side, you will need 3 male wires. The black one will go to GND, the red one will go to 5V, and the yellow one will go to pin 6.

Code

Code for everything

#include <Wire.h>
#include <LTR390.h>
#include <Servo.h>

LTR390 ltr390(I2C_ADDRESS);
Servo myServo;

void setup() {
  Serial.begin(115200);
  Wire.begin();
  myServo.attach(SERVO_PIN); // Attach the servo to pin 5

  if (!ltr390.init()) {
    Serial.println("LTR390 not connected!");
  }

  ltr390.setMode(LTR390_MODE_ALS);
  ltr390.setGain(LTR390_GAIN_3);
  Serial.print("Gain : ");
  switch (ltr390.getGain()) {
    case LTR390_GAIN_1: Serial.println(1); break;
    case LTR390_GAIN_3: Serial.println(3); break;
    case LTR390_GAIN_6: Serial.println(6); break;
    case LTR390_GAIN_9: Serial.println(9); break;
    case LTR390_GAIN_18: Serial.println(18); break;
  }
  
  ltr390.setResolution(LTR390_RESOLUTION_18BIT);
  Serial.print("Resolution : ");
  switch (ltr390.getResolution()) {
    case LTR390_RESOLUTION_13BIT: Serial.println(13); break;
    case LTR390_RESOLUTION_16BIT: Serial.println(16); break;
    case LTR390_RESOLUTION_17BIT: Serial.println(17); break;
    case LTR390_RESOLUTION_18BIT: Serial.println(18); break;
    case LTR390_RESOLUTION_19BIT: Serial.println(19); break;
    case LTR390_RESOLUTION_20BIT: Serial.println(20); break;
  }
}

void loop() {
  if (ltr390.newDataAvailable()) {
    if (ltr390.getMode() == LTR390_MODE_ALS) {
      Serial.print("Ambient Light Lux: "); 
      Serial.println(ltr390.getLux());
      ltr390.setGain(LTR390_GAIN_18);                  // Recommended for UVI - x18
      ltr390.setResolution(LTR390_RESOLUTION_20BIT);   // Recommended for UVI - 20-bit
      ltr390.setMode(LTR390_MODE_UVS);             
    } else if (ltr390.getMode() == LTR390_MODE_UVS) {
      float uvIndex = ltr390.getUVI();
      Serial.print("UV Index: "); 
      Serial.println(uvIndex);

      // Control the servo based on the UV index
      if (uvIndex < 0.10) {
        myServo.write(20); // Move servo to position 0
        delay(500);         // Wait for 500ms
      } else {
        myServo.write(160); // Move servo to position 180
        delay(500);          // Wait for 500ms
      }

      ltr390.setGain(LTR390_GAIN_3);                   // Recommended for Lux - x3
      ltr390.setResolution(LTR390_RESOLUTION_18BIT);   // Recommended for Lux - 18-bit
      ltr390.setMode(LTR390_MODE_ALS);
    }
  }
}