ESP32 Digital Privacy Window Tutorial

June 6, 2025·

Digital Privacy Window System

Introduction

This tutorial will guide you through building a Digital Privacy Window system using an ESP32 DevBoard to control a switchable (electrochromic or liquid crystal) window film. The motivation is to enable dynamic privacy and solar control for smart homes, offices, or any space where on-demand window opacity is desirable. By following this tutorial, you will gain hands-on experience in embedded programming, hardware integration, and smart device prototyping.

Learning Objectives

Interface an ESP32 DevBoard with a digital privacy window film.
Program the ESP32 to control window transparency via GPIO.
Understand the principles behind electrochromic and liquid crystal films.
Assemble, test, and troubleshoot basic embedded hardware.
Document and communicate technical processes and results.

Background Information

A digital privacy window uses switchable film (electrochromic or liquid crystal) that changes between transparent and opaque states when voltage is applied. This technology is used in offices, healthcare, retail, and homes to provide privacy at the touch of a button or via automation. The ESP32 DevBoard is a powerful, Wi-Fi/Bluetooth-enabled microcontroller that can be programmed to control such films through its GPIO pins.

Alternatives:

Smart blinds/shades (mechanical, less sleek)
Traditional curtains (manual, less automated)
Other microcontrollers (Arduino Uno, less powerful than ESP32)

Key Concepts:

PDLC (Polymer Dispersed Liquid Crystal): Film scatters light when unpowered, becomes clear when voltage aligns the crystals.
Electrochromic Film: Tints gradually with voltage.
GPIO: General-purpose input/output pin on the ESP32, used to switch the window state.

Getting Started

Before you begin, you’ll need to install software and gather hardware components.

Required Downloads and Installations

Arduino IDE
Download from arduino.cc and install for your OS (Windows, macOS, Linux).
Arduino IDE Install Guide
ESP32 Board Support Package
In Arduino IDE:
- Go to File > Preferences and add:
  https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
- Tools > Board > Boards Manager > Search “ESP32” > Install.
USB-to-Serial Drivers
Only if your ESP32 board is not detected. Download from the chip manufacturer’s website (e.g., CP210x or CH340).

Required Components

Component Name	Quantity
ESP32 DevBoard	1
USB Data Cable (ESP32)	1
Electrochromic or LC Window Film	1
MOSFET or Relay Module	1
Power Supply (per film specs)	1
Jumper Wires	5+
Breadboard (optional)	1

Required Tools and Equipment

Computer (Windows/macOS/Linux)
Internet access
(Optional) Soldering station
(Optional) Multimeter

Part 01: Setting Up the ESP32 Development Environment

Introduction

This section covers installing and configuring the Arduino IDE and ESP32 Board Support so you can program your ESP32 DevBoard.

Objective

Install Arduino IDE and ESP32 board support.
Connect ESP32 to your computer and verify communication.
Upload a test program to confirm setup.

Background Information

You’ll need basic computer skills and familiarity with installing software. No prior microcontroller experience is required.

Components

Computer
ESP32 DevBoard
USB Data Cable

Instructional

Download and install the Arduino IDE from arduino.cc.
Open Arduino IDE. Go to File > Preferences. Add
https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
to “Additional Boards Manager URLs.”
Go to Tools > Board > Boards Manager. Search for “ESP32” and install “ESP32 by Espressif Systems.”
Connect your ESP32 to your computer. Install drivers if needed.
Select your board (e.g., “ESP32 Dev Module”) and port under Tools.
Open File > Examples > 01.Basics > Blink. Upload to the ESP32.
If the onboard LED blinks, your setup is complete!

Example

Introduction

Let’s test your setup by uploading the “Blink” sketch to your ESP32.

Example

// ESP32 Blink Example int LED_BUILTIN = 2; void setup() { pinMode(LED_BUILTIN, OUTPUT); } void loop() { digitalWrite(LED_BUILTIN, HIGH); delay(1000); digitalWrite(LED_BUILTIN, LOW); delay(1000); }

Visual:
ESP32 Blink Example

Analysis

Confirms Arduino IDE and ESP32 board support are working.
Verifies USB communication.
Demonstrates the upload process for future code.

Additional Resources

Useful links

Part 02: Understanding and Preparing the Privacy Window Film

Introduction

This section introduces switchable privacy films and prepares you for installation and testing.

Objective

Understand how electrochromic and liquid crystal films work.
Prepare the film for installation and testing.
Learn best practices for handling and cleaning.

Background Information

Switchable films use voltage to change between clear and opaque states. Proper handling and testing before installation are critical to avoid damage.

Components

Privacy window film (electrochromic or LC)
Power supply (per film specs)
Clean glass or acrylic panel

Instructional

Inspect the film for any damage before use.
Test the film by connecting it to the power supply; observe the transition between states.
Clean the glass thoroughly before applying the film—80% of installation issues are due to dirt.
Carefully peel and apply the film, following manufacturer’s instructions for alignment and adhesion.
Connect film wiring to the power supply, ensuring correct polarity and voltage.

Example

Introduction

We’ll test the privacy film’s switching function before installation.

Example

Visual:
Privacy Film Test

Steps:

Connect wires as per film datasheet.
Apply power; film should turn clear.
Remove power; film returns to opaque.

Analysis

Confirms film is functional before installation.
Demonstrates the principle of voltage-controlled transparency.
Ensures no defects before permanent mounting.

Additional Resources

Useful links

Part 03: Wiring and Controlling the Privacy Window with ESP32

Introduction

This section covers connecting the ESP32 to the privacy film and programming it to control transparency via a GPIO pin.

Objective

Wire the ESP32 to a relay or MOSFET for safe film control.
Write code to toggle the film’s state.
Test dynamic switching via software.

Background Information

The ESP32 cannot drive the film directly (due to voltage/current requirements), so a relay or MOSFET acts as a switch. GPIO pins send control signals to these components.

Components

ESP32 DevBoard
Relay or MOSFET module
Privacy window film (installed)
Jumper wires
Power supply (for film)

Instructional

Connect the ESP32 GPIO pin to the relay or MOSFET control input.
Wire the relay/MOSFET output to the privacy film and its power supply.
In Arduino IDE, write a sketch that toggles the GPIO pin HIGH/LOW to switch the film.
Upload the code and observe the window film switching between states.

Example

Introduction

Let’s program the ESP32 to switch the privacy film on and off with a button press.

Example

#define FILM_PIN 5

void setup() { pinMode(FILM_PIN, OUTPUT); }

void loop() { digitalWrite(FILM_PIN, HIGH); // Film ON (clear) delay(5000); digitalWrite(FILM_PIN, LOW); // Film OFF (opaque) delay(5000); }

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Visual:
ESP32 to Relay/MOSFET to Film

Analysis

The ESP32 toggles the relay/MOSFET, switching the film.
Demonstrates embedded control of physical hardware.
Code can be extended for remote, sensor, or scheduled control.

Additional Resources

Useful links

Part 04: Troubleshooting, Safety, and Best Practices

Introduction

This section addresses common issues, safety tips, and best practices for a reliable, safe installation.

Objective

Identify and resolve common hardware/software issues.
Apply safe handling and wiring practices.
Document and communicate troubleshooting steps.

Background Information

Working with high voltages and delicate films requires caution. Many issues stem from wiring errors, poor connections, or software bugs.

Components

All previously listed components
Multimeter (for diagnostics)

Instructional

Double-check all wiring before applying power.
Use a multimeter to verify voltages at each stage.
If the film does not switch, check:
- Power supply output
- Relay/MOSFET operation
- ESP32 GPIO output
- Film wiring and connections
Consult datasheets and guides for troubleshooting tips.
Always disconnect power before making changes to the circuit.

Example

Introduction

We’ll diagnose a non-switching film.

Example

Use a multimeter to check voltage at the film terminals when the relay/MOSFET is activated.
Use Arduino IDE’s Serial Monitor to print GPIO states for debugging.

Analysis

Confirms whether the issue is in software, wiring, or hardware.
Reinforces safe diagnostic practices.

Additional Resources

Useful links

Exploring Analog Inputs with a Potentiometer Distance Finder with ESP and Ultrasonic