Overview
In this project, we will make Dark Activated Night Lamp using LDR (Light Dependent Resistor) & Raspberry Pi Pico Board. This project would help you in understanding how automatic day/ night activated LEDs work.
The lights outside our house had to be switched on every day at night, and more often than not we ended up forgetting to switch them off in the morning. A simple device with the Raspberry Pi Pico can prevent wastage of energy even in devices like torches left on during the day and also be a convenient way to switch on the light without getting up from your table.
This project can be simply made with a Raspberry Pi Pico, LDR & LED. In this case, Raspberry Pi Pico can be programmed to read the analog voltage from the LDR-resistor network. Then the value is compared to a reference value for certain decision-making. The decision may be switching ON the electronic lights automatically when the dark is detected or switching OFF the electronic lights automatically when light is detected. You can also build Automatic Street Light using this LDR Sensor.
Components Required
In this guide, I used Elecrow Raspberry Pi Pico Starter Kit to test different Modules. You can buy the kit and perform some other operations as well. From this kit, you can use the following components.
1. Raspberry Pi Pico Board -1
2. LDR Sensor Module – 1
3. Red LED – 1
4. Breadboard -1
5. Jumper Wires – 10
6. Micro-USB Cable
Light Dependent Resistor (LDR)
Light Dependent Resistor or LDR or Photoresistor are electronic components that are often used in electronic circuit designs where it is necessary to detect the presence or the level of light. LDRs are very different from other forms of resistor like the carbon film resistor, metal oxide film resistor, metal film resistor, and the like that are widely used in other electronic designs. They are specifically designed for their light sensitivity and the change in resistance this causes.
When light falls upon it, then the resistance changes. Values of the resistance of the LDR may change over many orders of magnitude the value of the resistance falling as the level of light increases. It is not uncommon for the values of resistance of an LDR or photoresistor to be several megohms in darkness and then to fall to a few hundred ohms in bright light.
Circuit Diagram & Hardware Setup
The simple connection diagram for Dark Activated Night Lamp using LDR & Raspberry Pi Pico is given below.
Connect the VCC, GND & Signal Pin of the LDR Sensor Module to 5V, GND & GP2 Pins of Raspberry Pi Pico. Connect the LED positive terminal to GP0 of Pico Board & GND to GND.
MicroPython Code/Program
Open your Thonny IDE & Copy the following code & paste it to the editor window.
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from machine import Pin import time led = Pin(0, Pin.OUT) ldr = Pin(2, Pin.IN, Pin.PULL_DOWN) while True: if ldr.value(): led.value(1) time.sleep(0.5) else: led.value(0) time.sleep(0.5) |
Now you can run this code to test the working of the circuit.
When you place a finger on the surface of the LDR Sensor or bright the circuit in complete dark, the LED will get activated.
When the LDR detects light or if you remove your finger from the LDR surface, the LED will turn off.
This is how you can make your own Dark Activated Night Lamp using LDR & Raspberry Pi Pico.
