SENSORS/ACTUATORS

ESP32 MicroPython LDR Module

This tutorial instructs you you how to use a ESP32 and an LDR light sensor module to monitor and measure light levels. In detail, we will learn:

How to connect the LDR light sensor module to a ESP32.
How to write MicroPython code for the ESP32 to detect light with the LDR light sensor's digital signal.
How to write MicroPython code for the ESP32 to measure light intensity using the LDR light sensor's analog signal.

ESP32 MicroPython LDR Light Sensor Module

Hardware Preparation

1	×	ESP-WROOM-32 Dev Module
1	×	USB Cable Type-C
1	×	LDR Light Sensor Module
1	×	Jumper Wires
1	×	(Recommended) Screw Terminal Expansion Board for ESP32

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	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 helps detect light or measure the amount of light around it. It provides two options: a digital output and an analog output.

Pinout

The LDR light sensor module comes with four pins:

VCC pin: Attach this pin to VCC (3.3V to 5V).
GND pin: Attach this pin to GND (0V).
DO pin: This is a digital output pin. It shows HIGH in the dark and LOW in the light. Adjust the potentiometer to change the sensitivity to light and dark.
AO pin: This is an analog output pin. The output value decreases in bright conditions and increases in dark conditions.

image source: diyables.io

It also features two LED lights:

A PWR-LED indicator lights up to show the power is on.
A DO-LED indicator displays the light status on the DO pin: it lights up when there is light and turns off in the dark.

How It Works

DO Pin:

The potentiometer adjusts the light threshold.
DO pin is LOW (DO-LED off) when light is brighter than the threshold.
DO pin is HIGH (DO-LED on) when light is dimmer than the threshold.

AO Pin:

AO pin reading varies with light intensity.
Lower reading means more light.
Higher reading means darker conditions.
Potentiometer does not affect AO pin value.

This method lets you adjust DO pin sensitivity with the potentiometer while getting accurate light measurements from the AO pin.

Wiring Diagram

The light sensor module offers two outputs, DO and AO, which can be used individually or together.

How to connect ESP32 and ldr module using breadboard

The wiring diagram between ESP32 MicroPython LDR Light Sensor Module

This image is created using Fritzing. Click to enlarge image

How to connect ESP32 and ldr module using screw terminal block breakout board

ESP32 MicroPython Code - Read value from DO pin

""" This ESP32 MicroPython code was developed by newbiely.com This ESP32 MicroPython code is made available for public use without any restriction For comprehensive instructions and wiring diagrams, please visit: https://newbiely.com/tutorials/esp32-micropython/esp32-micropython-ldr-module """ from machine import Pin import utime # For timing functions DO_PIN = Pin(13, Pin.IN) # The ESP32 pin GPIO13 connected to the DO pin of the LDR module while True: light_state = DO_PIN.value() # Read the digital value from the pin if light_state == 1: print("The light is NOT present") else: print("The light is present") utime.sleep(0.5) # Add a small delay to avoid spamming the output

Detailed Instructions

Here’s instructions on how to set up and run your MicroPython code on the ESP32 using Thonny IDE:

Make sure Thonny IDE is installed on your computer.
Confirm that MicroPython firmware is loaded on your ESP32 board.
If this is your first time using an ESP32 with MicroPython, check out the ESP32 MicroPython Getting Started guide for step-by-step instructions.
Connect the ESP32 the LDR module according to the provided diagram.
Connect the ESP32 board to your computer with a USB cable.
Open Thonny IDE on your computer.
In Thonny IDE, go to Tools Options.
Under the Interpreter tab, choose MicroPython (ESP32) from the dropdown menu.
Make sure the correct port is selected. Thonny IDE usually detects it automatically, but you might need to select it manually (like COM12 on Windows or /dev/ttyACM0 on Linux).
Copy the provided MicroPython code and paste it into Thonny\'s editor.
Save the code to your ESP32 by:

Clicking the Save button or pressing Ctrl+S.
In the save dialog, choose MicroPython device.
Name the file main.py.

Click the green Run button (or press F5) to execute the script.
Use your hand or an object to block and unblock the light on the LDR sensor module.
Check out the message in the Shell at the bottom of Thonny.

Shell x

>>> %Run -c $EDITOR_CONTENT

MPY: soft reboot The light is present The light is present The light is NOT present The light is NOT present The light is NOT present The light is present The light is present The light is present

MicroPython (ESP32) • CP2102 USB To UART Bridge Controller @ COM12 ≡

If the LED is always on or off, adjust the light sensitivity using the potentiometer. You can now modify the code to control an LED, light switch, or servo motor based on light detection. For detailed instructions, refer to the tutorials at the end of this document.

※ NOTE THAT:

This tutorial demonstrates how to use the adc.read() function to read values from an ADC (Analog-to-Digital Converter) connected to a LDR module. The ESP32's ADC is suitable for projects that do not require high precision. However, if your project needs accurate measurements, keep the following in mind:

The ESP32 ADC is not perfectly accurate and may require calibration for precise results. Each ESP32 board may 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 desire.

For projects requiring high precision, consider using an external ADC (e.g., ADS1115) with the ESP32 or opt for an Arduino, which has a more reliable ADC. If you still wish to calibrate the ESP32 ADC, refer to the ESP32 ADC Calibration Driver.

ESP32 MicroPython Code - Read value from AO pin

""" This ESP32 MicroPython code was developed by newbiely.com This ESP32 MicroPython code is made available for public use without any restriction For comprehensive instructions and wiring diagrams, please visit: https://newbiely.com/tutorials/esp32-micropython/esp32-micropython-ldr-module """ from machine import ADC, Pin import utime # For timing functions AO_PIN = ADC(Pin(36)) # The ESP32 pin GPIO36 (ADC0) connected to the AO pin of the LDR module # Set the ADC width (resolution) to 12 bits AO_PIN.width(ADC.WIDTH_12BIT) # Set the attenuation to 11 dB, allowing input range up to ~3.3V AO_PIN.atten(ADC.ATTN_11DB) while True: light_value = AO_PIN.read() # Read the analog value (0-4095) print(light_value) # Print the analog value utime.sleep(1) # Add a small delay to avoid spamming the output

Detailed Instructions

Please follow these instructions one by one:

Copy the above code and open it in the Thonny IDE.
Click the green Run button (or press F5) to run the script. The script will execute.
Use your hand or an object to block and unblock the light on the LDR sensor module.
Check out the message in the Shell at the bottom of Thonny.

Shell x

>>> %Run -c $EDITOR_CONTENT

MPY: soft reboot 580 584 584 2289 2713 3782 3826 4006 4010 4050 4054 2581 2185 1385 688

MicroPython (ESP32) • CP2102 USB To UART Bridge Controller @ COM12 ≡

Video Tutorial

Learn More

ESP32 MicroPython Light Sensor

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