IoT ESP8266 Lux Meter using BH1750 Light Sensor & Blynk
In this project, we'll make an IoT ESP8266-based Lux meter or light meter using a BH1750 ambient light sensor and watch it on Blynk. With this sensor, we can figure out how much light the…
Know the mission before touching a wire.
Understand what you are making, prepare the right tools, and make the workbench safe.
Project details
IoT ESP8266 Lux Meter using BH1750 Light Sensor & Blynk is a iot project. In this project, we'll make an IoT ESP8266-based Lux meter or light meter using a BH1750 ambient light sensor and watch it on Blynk. With this sensor, we can figure out how much light the…
- Source pages
- 1172-1175
- Named parts
- 3
- Build goal
- Working, tested prototype
Tools you need
- Digital multimeter
- Wire stripper and side cutters
- Soldering iron with a fine tip
- Current-limited bench supply
- Computer with a data-capable USB cable
Use eye protection, good lighting, and a clean insulated surface throughout the build.
Safety precautions
- Disconnect every power source before changing a connection.
- Check component polarity, pinout, and supply voltage twice.
- Use a current limit for the first power-up.
- Keep liquids, loose metal, and uninsulated wires away from the bench.
Gather, identify, and understand every part.
Use the standardized inventory, then open What's this? to learn each part's role, advantages, limitations, handling, and specifications.
What's this?Image, role, pros, cons, handling & specifications
MODULE LEARNING VIEWNodeMCU Board (NodeMCU ESP8266 12E Wifi Module)
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for NodeMCU Board (NodeMCU ESP8266 12E Wifi Module); similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
What's this?Image, role, pros, cons, handling & specifications
Light Sensor (BH1750 Ambient Light Sensor)
A sensor converts a physical condition into an electrical signal the circuit can measure.
What it does hereIt provides project input as an analogue, digital, resistive, frequency, or calibrated signal.
Buy / compare this part ↗Advantages
- Adds real-world awareness
- Can usually be tested independently
- Often supports calibration
Limitations
- Readings can drift
- Placement affects results
- Some sensors need warm-up or calibration
Handling
- Protect the sensing surface
- Observe supply voltage and polarity
- Keep signal leads away from noisy power wiring
Specifications to verify
- Use the exact model, value, package, and rating listed for Light Sensor (BH1750 Ambient Light Sensor); similar-looking parts are not always interchangeable.
- Confirm supply range, output type, measurement range, accuracy, response time, and pin order.
What's this?Image, role, pros, cons, handling & specifications
ESP8266-BASED - controller board / IC
A programmable controller that reads inputs, makes decisions, and drives the project's outputs.
What it does hereIt is the control centre and must use the documented board, pin map, supply, and logic level.
Buy / compare this part ↗Advantages
- Reprogrammable and reusable
- Large learning ecosystem
- Complex behaviour remains changeable
Limitations
- GPIO voltage and current are limited
- Some pins affect boot or communication
- Loads normally need a driver
Handling
- Disconnect power before rewiring
- Avoid static discharge
- Never power motors, relays, or pumps directly from GPIO
Specifications to verify
- Use the exact model, value, package, and rating listed for ESP8266-BASED - controller board / IC; similar-looking parts are not always interchangeable.
- Confirm operating voltage, logic level, pinout, memory, USB interface, and maximum GPIO current.
Connect one verified path at a time.
Explore the named components and standardized signal flow, then use Source Check to verify exact physical pins, values, and topology before applying power.
Trace this circuit.
IoT ESP8266 Lux Meter using BH1750 Light Sensor & Blynk: interactive parts, standardized terminals, responsive anchored wires, student explanations, and the original circuit reference in one shared system.
Trace before wiring
Follow power, ground, inputs, processing, and outputs in that order. Never guess a pin from package shape alone.
Connect with power off
Make short, labelled connections and share a common ground only where the schematic requires it.
Inspect every joint
Check continuity, polarity, adjacent shorts, and loose connections before the first power-up.
Open all source diagrams and build views 3 visuals
Confirm the hardware-only control path.
This project does not include firmware in the source. The circuit itself provides the required behaviour.
How to connect
- Match every controller label to the circuit view and source pin map.
- Join grounds before signal wires when separate low-voltage supplies are used.
- Keep motors, relays, pumps, and other loads on a suitable driver and external supply.
Common mistakes
Reversed VCC/GND, board-label versus GPIO-number confusion, missing common ground, and charge-only USB cables.
Troubleshoot
Disconnect loads, continuity-test one path at a time, then test with a current limit.
Software preparation
No IDE, board package, library, or firmware upload is required for this project.
If you add a programmable controller as an extension, document its pin map separately.
How to upload code
The original design is implemented entirely in hardware, so proceed after verifying the circuit and supply.
Assemble, deploy, test, and troubleshoot.
Use the complete source notes in build order, then pass the final checks before calling the project finished.
Build in functional stages
- Power and regulation
- Controller or processing stage
- Inputs and sensors
- Outputs and loads
- Enclosure and strain relief
Power up safely
- Inspect unpowered continuity first
- Apply the lowest safe current limit
- Measure supply rails before signals
- Add one load at a time
- Record expected and actual results
Work from simple to complex
- Confirm power, ground, polarity, and orientation
- Compare each pin with the source
- Test inputs separately from outputs
- Replace only one variable at a time
- Power off before every correction
Follow the documented instructions.
These notes come from this project's source and remain in their original order.
Project overview
Project build noteIn this project, we'll make an IoT ESP8266-based Lux meter or light meter using a BH1750 ambient light sensor and watch it on Blynk. With this sensor, we can figure out how much light there is in lux units and see how bright the light is around us. This sensor can be used for a lot of different things. For example, it can be used to change the brightness of the LCD screen on a mobile phone by detecting the light around it. It can also be used to turn street lights on and off based on how dark it is. Earlier, we made Lux/light Meter using BH1750 Sensor & Arduino. On a 162 LCD Display, the amount of light in lux is shown. Now, instead of showing the data on an LCD screen, we will send it to the Blynk application. With the Blynk app, we can check on the amount of light in a
certain place from anywhere in the world. We need some hardware, like the NodeMCU ESP8266 & BH1750 Ambient Light Sensor Module, to do that. This is a BH1750 light intensity sensor breakout board. It has an I2C bus interface and a digital Ambient Light Sensor IC. This IC is best for getting information about ambient light in mobile phones so that the brightness of the screen can be changed based on how bright the room is. This sensor can measure light accurately up to 65535 LUX. It uses very little electricity and uses a photodiode to detect light. 2.4V to 3.6V can be used to power the BH1750. The main part of the sensor is the BH1750FVI module, which needs 3.3V to work. So, the circuit uses a voltage regulator. I2C communication with the address 0x23 uses the pins SDA and SCL. With these pins, pullup resistors with a value of 4.7k are used.
Circuit Diagram
Project build noteNow, let's connect the NodeMCU ESP8266 Board to the BH1750 Ambient Light Sensor. It's not hard to see the link. Connect the I2C pins of the BH1750, which are SDA and SCL, to D1 and D2 on the NodeMCU board.
Connect BH1750's 3.3V pin to NodeMCU's 3.3V pin and GND to GND. The circuit is easy to put together on a breadboard.
Part Required
Project build noteNodeMCU Board (NodeMCU ESP8266 12E Wifi Module) Light Sensor (BH1750 Ambient Light Sensor) Jumper Wires Breadboard
Setting up the Blynk app
Project build noteWithout the Blynk Application, the IoT-based Lux Meter Project would not be complete. The Internet of Things is what Blynk is made for. It can
remotely control hardware, show sensor data, store data, visualize it, and do a lot of other cool things. Get the Blynk app from the Google Play Store and install it. The App Store has downloads for people who use IOS. Once the app is installed, open it and sign up using your email address and password. You can make your UI by dragging, dropping, and filling in details, as well as assigning virtual pins. Once the UI is set up, you can send an email to ask for the authentication token. For the code, you will need the Authentication Token. Monitoring the amount of light in the Blynk app Once the code is uploaded, the NodeMCU Board will use the assigned Wifi SSID and Password to connect to the wifi. Once the Nodemcu is connected to WiFi, it will begin sending data to the Blynk Server. The picture above shows that you can use the Blynk app to check the Light Intensity data.
You built IoT ESP8266 Lux Meter using BH1750 Light Sensor & Blynk.
You followed the full workflow from understanding the mission to testing the finished project. That is a real engineering achievement - well done.
IoT Based TDS Meter using ESP8266 for Water Quality Monitoring
Ready to reuse what you learned in another project from the same track?
Start this project →