SENSORS/ACTUATORS

ESP32 C3 Super Mini - LDR Module

The LDR light sensor module is a simple yet powerful component for detecting and measuring light levels with your ESP32 C3 Super Mini. This beginner-friendly tutorial will show you how to connect and program the LDR module to sense light in your projects.

In this tutorial, we will learn how to use an ESP32 C3 Super Mini and an LDR light sensor module together to detect and measure the amount of light. Here's what we'll cover:

What an LDR light sensor module is and how it works
How to wire the LDR light sensor module to ESP32 C3 Super Mini
How to program ESP32 C3 Super Mini to detect light using digital output
How to program ESP32 C3 Super Mini to measure light levels using analog output
How to read and display both digital and analog sensor values

image source: diyables.io

Afterward, you can change the code to make an LED or a light bulb turn on (using a relay) when it senses light.

If you're interested in a light sensor in its raw form, I suggest exploring the tutorial for the ESP32 C3 Super Mini - Light Sensor.

Hardware Preparation

1	×	ESP32 C3 Super Mini
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	LDR Light Sensor Module
1	×	Breadboard
1	×	Jumper Wires

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of LDR Light Sensor Module

The LDR light sensor module is a digital and analog sensor that detects and measures ambient light intensity in your environment.

Operating Voltage: 3.3V to 5V (compatible with ESP32 C3 Super Mini)
Output Types: Digital (DO) and Analog (AO) outputs available
Built-in Potentiometer: Adjustable sensitivity threshold for digital output
LED Indicators: Power LED and status LED for easy monitoring
Beginner-Friendly: Easy to connect and program with simple Arduino code
Versatile Applications: Perfect for light-activated switches, automatic lighting, and environmental monitoring
Compact Design: Small module fits easily on breadboards

Pinout

The LDR light sensor module includes four connection pins for interfacing with your ESP32 C3 Super Mini:

VCC: Power supply pin - connect to 3.3V or 5V on ESP32 C3 Super Mini
GND: Ground pin - connect to GND on ESP32 C3 Super Mini
DO: Digital output pin - outputs HIGH when dark, LOW when bright (threshold adjustable via potentiometer)
AO: Analog output pin - outputs variable voltage proportional to light intensity (lower value = brighter light)

image source: diyables.io

Additionally, the LDR light sensor module is equipped with two LED indicators:

The PWR-LED indicator shows the power status.
The DO-LED indicator reflects the state of light on the DO pin: it illuminates when there is light and remains off when it is dark.

How It Works

Regarding the DO pin:

The LDR light sensor module has a potentiometer that allows you to adjust the sensitivity or threshold for detecting light.
When the light intensity in the surrounding environment is above the set threshold (considered as light), the output of the sensor on the DO pin becomes LOW, and the DO-LED turns on.
When the light intensity in the surrounding environment is below the set threshold (considered as dark), the output of the sensor on the DO pin becomes HIGH, and the DO-LED turns off.

Regarding the AO pin:

The value read from the AO pin is inversely proportional to the light intensity in the surrounding environment. In other words, as the light intensity increases (brighter), the value on the AO pin decreases.
Similarly, as the light intensity decreases (darker), the value on the AO pin increases.

It's important to note that adjusting the potentiometer does not affect the value on the AO pin.

Wiring Diagram

This section shows how to connect the LDR light sensor module to your ESP32 C3 Super Mini.

Note: You can use the digital output (DO), analog output (AO), or both depending on your project needs.

The wiring diagram between ESP32 C3 Super Mini LDR Light Sensor Module

This image is created using Fritzing. Click to enlarge image

The wiring diagram between ESP32 C3 Super Mini and the LDR light sensor module when using both AO an DO.

LDR Module Pin	ESP32 C3 Super Mini Pin
VCC	3.3V
GND	GND
DO	GPIO6
AO	A5 (GPIO5 / ADC1_CH5)

ESP32 C3 Super Mini Code - Read value from DO pin

This code demonstrates how to use the ESP32 C3 Super Mini to read the digital output from the LDR light sensor module.

Configures GPIO8 as digital input for the DO pin
Reads HIGH or LOW signal from the sensor
Detects light or dark conditions based on threshold
Displays light status on Serial Monitor
Adjustable sensitivity using onboard potentiometer

/* * This ESP32 C3 Super Mini code was developed by newbiely.com * * This ESP32 C3 Super Mini code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp32-c3/esp32-c3-super-mini-ldr-module */ #define DO_PIN D6 // The ESP32 C3 SuperMini pin connected to DO pin of the ldr module void setup() { // Initialize the Serial to communicate with the Serial Monitor. Serial.begin(9600); // initialize the ESP32's pin as an input pinMode(DO_PIN, INPUT); } void loop() { int light_state = digitalRead(DO_PIN); if (light_state == HIGH) Serial.println("It is dark"); else Serial.println("It is light"); }

Detailed Instructions

New to ESP32 C3 Mini? Complete our Getting Started with ESP32 C3 Mini tutorial first to set up your development environment.
Setup Arduino IDE: If you are new to ESP32 C3 Super Mini, refer to the tutorial on how to set up the environment for ESP32 C3 Super Mini in the Arduino IDE.
Wire the components: Connect the LDR light sensor module to ESP32 C3 Super Mini according to the wiring diagram shown above.
Connect ESP32: Plug the ESP32 C3 Super Mini into your computer using a USB Type-C cable.
Select board: Open Arduino IDE and select the ESP32 C3 Super Mini board and its corresponding COM port.
Upload code: Copy the above code and open with Arduino IDE, then click Upload button to upload code to ESP32 C3 Super Mini.
Test the sensor: Cover and uncover the LDR light sensor module with your hand or an object to test light detection.
View results: Open the Serial Monitor to see the light detection status in real-time.
Adjust sensitivity: If needed, turn the potentiometer on the module to adjust the light detection threshold.
Pro Tip: Mark the potentiometer position once you find the perfect sensitivity setting for your lighting conditions.

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')

New Line

9600 baud

It is light It is light It is dark It is dark It is dark It is light It is light It is light

Ln 11, Col 1

ESP32C3 Dev Module on COM15

If you observe that the LED status remains constantly on or off, regardless of the presence of light, you have the option to adjust the potentiometer. This adjustment allows you to finely tune the light sensitivity of the sensor.

Furthermore, the code can be modified according to your requirements. For instance, you can program the LED to activate or the light to turn on when light is detected. Additionally, you have the flexibility to make a servo motor rotate. Detailed instructions and tutorials on these customization options can be found at the end of this guide.

ESP32 C3 Super Mini Code - Read value from AO pin

This code shows how to read analog values from the LDR light sensor module for precise light measurements.

Configures GPIO3 (A0) as analog input for the AO pin
Reads analog values from 0 to 4095 (12-bit ADC)
Measures continuous light intensity levels
Lower values indicate brighter light
Higher values indicate darker conditions

/* * This ESP32 C3 Super Mini code was developed by newbiely.com * * This ESP32 C3 Super Mini code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp32-c3/esp32-c3-super-mini-ldr-module */ #define AO_PIN A5 // The ESP32 C3 SuperMini pin connected to AO pin of the ldr module void setup() { // Initialize the Serial to communicate with the Serial Monitor. Serial.begin(9600); // set the ADC attenuation to 11 dB (up to ~3.3V input) analogSetAttenuation(ADC_11db); } void loop() { int light_value = analogRead(AO_PIN); Serial.print("The AO value: "); Serial.println(light_value); }

Detailed Instructions

New to ESP32 C3 Mini? Complete our Getting Started with ESP32 C3 Mini tutorial first to set up your development environment.
Upload code: Copy the above code and open with Arduino IDE, then click Upload button.
Test the sensor: Cover and uncover the LDR light sensor module with your hand or move it to different lighting conditions.
Monitor values: Open the Serial Monitor to see the analog light level readings.
Observe changes: Notice how values increase when you block light and decrease when you add light.
Pro Tip: Record the minimum and maximum values in your environment to map them to meaningful ranges like percentages or lux levels.

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')

New Line

9600 baud

The AO value: 145 The AO value: 146 The AO value: 146 The AO value: 572 The AO value: 1678 The AO value: 1945 The AO value: 2956 The AO value: 3001 The AO value: 3098 The AO value: 4005 The AO value: 4005 The AO value: 1645 The AO value: 1546 The AO value: 346 The AO value: 172

Ln 11, Col 1

ESP32C3 Dev Module on COM15

※ NOTE THAT:

This tutorial uses the analogRead() function to read values from an ADC (Analog-to-Digital Converter) connected to a sensor or component. The ESP32 C3 Super Mini's ADC is suitable for projects that do not require high accuracy. However, for projects needing precise measurements, keep the following in mind:

The ESP32 C3 Super Mini's ADC is not perfectly accurate and might require calibration for correct results. Each ESP32 C3 Super Mini board can vary slightly, so calibration is necessary for each individual board.
Calibration can be challenging, especially for beginners, and might not always yield the exact results you want.

For projects requiring high precision, consider using an external ADC (e.g ADS1115) with the ESP32 C3 Super Mini or using another Arduino, such as the Arduino Uno R4 WiFi, which has a more reliable ADC. If you still want to calibrate the ESP32 C3 Super Mini's ADC, refer to the ESP32 ADC Calibration Driver.

Application Ideas

Here are some practical projects you can build using the ESP32 C3 Super Mini and LDR light sensor module:

Automatic Night Light: Turn on lights automatically when it gets dark in your room
Smart Curtain Controller: Open or close curtains based on sunlight intensity
Solar Panel Tracker: Optimize solar panel position to face the brightest light source
Energy-Saving System: Automatically turn off unnecessary lights when natural light is sufficient
Plant Growth Monitor: Track light exposure for indoor plants and gardens
Security System: Detect when lights are turned on or off in monitored areas
Photography Light Meter: Measure ambient light for camera settings

Video Tutorial

Watch the video below for a visual walkthrough of this project.

Challenge Yourself

Try these challenges to expand your skills with the ESP32 C3 Super Mini and LDR light sensor module:

Easy: Add an LED that turns on when the room is dark and off when it's bright
Easy: Display "Bright", "Medium", or "Dark" based on different analog value ranges
Medium: Control a servo motor to rotate based on light intensity levels
Medium: Create a light-activated alarm that triggers a buzzer when light is detected
Advanced: Build a data logger that records light levels with timestamps to an SD card
Advanced: Create an automatic plant watering system that only waters when light levels are optimal

Function References

Learn More

ESP32 C3 Super Mini - Light Sensor

※ OUR MESSAGES

As freelancers, We are AVAILABLE for HIRE. See how to outsource your project to us
Please feel free to share the link of this tutorial. However, Please do not use our content on any other websites. We invested a lot of effort and time to create the content, please respect our work!