Hardware Specifications

This page describes the hardware components, requirements, and pin configuration for the ESP32 Distance Sensor project.

Hardware Components

Required Components

ESP32 Development Board

  • Model: ESP32-WROOM-32 or compatible

  • Flash: 4MB minimum (project optimized for 4MB modules)

  • RAM: 520KB SRAM (standard ESP32)

  • WiFi: 2.4 GHz 802.11 b/g/n

  • Power: 5V via USB or external supply

Recommended Boards:

  • ESP32 DevKitC

  • ESP32-WROOM-32 Development Board

  • NodeMCU-32S

  • Any ESP32 board with accessible GPIO pins

WS2812 LED Strip

  • Type: Individually addressable RGB LEDs (NeoPixel compatible)

  • Quantity: 40 LEDs (configurable in software)

  • Voltage: 5V

  • Data Interface: Single-wire serial protocol

  • Current: ~60mA per LED at full brightness (2.4A total for 40 LEDs)

Purchase Considerations:

  • Pre-soldered strips with connectors are easier to work with

  • Waterproof (IP65) versions available for outdoor use

  • Individual LEDs can be used instead of strips

HC-SR04 Ultrasonic Sensor

  • Measurement Range: 2cm - 400cm

  • Accuracy: ±3mm

  • Operating Voltage: 5V (works with 3.3V trigger)

  • Interface: Digital trigger and echo pins

  • Update Rate: Up to 50Hz (project uses 10Hz)

Features:

  • Non-contact distance measurement

  • 15° measurement angle

  • Compact and affordable

Cables & Connectors

  • USB Cable: Micro-USB or USB-C (depending on ESP32 board)

  • Jumper Wires: Male-to-female for sensor connections

  • LED Strip Connectors: JST connectors (often included with LED strips)

Optional Components

External 5V Power Supply

Recommended if:

  • Using all 40 LEDs at high brightness

  • USB power insufficient (brownout issues)

  • Deploying in permanent installation

Specifications:

  • Voltage: 5V DC

  • Current: 3A minimum (5A recommended for full brightness)

  • Connector: Barrel jack or screw terminals

Power Distribution

  • Breadboard or perfboard for clean connections

  • Voltage regulator (if using higher voltage supply)

  • Capacitors for power filtering (100µF, 0.1µF)

Enclosure

  • Waterproof box for outdoor installations

  • Mounting hardware for garage ceiling/wall

  • Cable management clips

Pin Configuration

GPIO Pin Assignments

Pin Configuration

Component

Function

GPIO Pin

Notes

WS2812 LED Strip

Data

GPIO12

RMT peripheral for precise timing

HC-SR04 Sensor

Trigger

GPIO14

Output: 10µs pulse to trigger measurement

HC-SR04 Sensor

Echo

GPIO13

Input: High pulse duration = distance

Power

VCC

5V

From USB or external supply

Ground

GND

GND

Common ground for all components

Wiring Diagram

ESP32 to HC-SR04 Sensor:

ESP32           HC-SR04
GPIO14   ---→   Trig
GPIO13   ←---   Echo
5V       ---→   VCC
GND      ---→   GND

ESP32 to WS2812 LED Strip:

ESP32           WS2812 Strip
GPIO12   ---→   DIN (Data In)
5V       ---→   5V / VCC
GND      ---→   GND

Power Considerations:

  • USB Power: Sufficient for testing and low LED brightness

  • External 5V: Connect to ESP32 VIN (not 3.3V pin) and LED strip VCC

  • Common Ground: All components must share the same GND connection

Warning

Current Draw: WS2812 LEDs can draw up to 60mA each at full white brightness. 40 LEDs = 2.4A total. USB ports typically provide 500-900mA. For full brightness, use an external 5V power supply rated for at least 3A.

Pin Selection Rationale

GPIO12 (LED Strip):

  • Supports RMT (Remote Control) peripheral for precise timing

  • WS2812 requires precise 800kHz timing (T0H=0.4µs, T1H=0.8µs)

  • RMT hardware generates timing automatically, no CPU overhead

GPIO13/14 (HC-SR04):

  • General-purpose GPIO pins without special constraints

  • Not used by flash, UART, or other critical functions

  • Adjacent pins for clean wiring

Avoided Pins:

  • GPIO0, GPIO2: Boot mode pins (pulled up/down at boot)

  • GPIO1, GPIO3: UART0 (console/programming)

  • GPIO6-11: Connected to flash memory (do not use)

Technical Specifications

System Requirements

Technical Specifications

Specification

Value

Microcontroller

ESP32-WROOM-32 (240MHz dual-core, 4MB flash, 520KB RAM)

LED Strip

40× WS2812 individually addressable RGB LEDs

Distance Sensor

HC-SR04 ultrasonic (2cm-400cm range, ±3mm accuracy)

Update Rate

10Hz sensor readings, real-time LED updates

WiFi

2.4 GHz 802.11 b/g/n, AP and STA modes

Web Interface

HTTP server (HTTPS not yet implemented)

Power Consumption

~80mA (ESP32) + up to 2.4A (LEDs at full brightness)

Operating Voltage

5V (3.3V logic levels for ESP32)

Memory Usage

~59% flash, ~18% DRAM, ~76% IRAM (optimized for 4MB)

Development Framework

ESP-IDF v5.4.1, FreeRTOS

Performance Characteristics

Distance Measurement:

  • Range: 10cm - 50cm (configurable)

  • Resolution: 1mm (millimeter precision)

  • Update Rate: 10Hz (100ms per reading)

  • Accuracy: ±3mm (sensor specification)

LED Display:

  • LEDs: 40 individually addressable

  • Colors: 16.7 million (24-bit RGB)

  • Brightness: 0-255 per channel (configurable)

  • Response Time: <10ms (real-time feedback)

Network:

  • WiFi Modes: AP (Access Point) and STA (Station)

  • AP SSID: “ESP32-Distance-Sensor” (default)

  • Web Server: HTTP on port 80

  • Configuration: Captive portal for easy setup

Bill of Materials (BOM)

Bill of Materials

Qty

Component

Ref

Est. Cost

Notes

1

ESP32 Development Board

U1

$8-15

ESP32-WROOM-32 or compatible

1

WS2812 LED Strip (40 LEDs)

LED1

$10-20

5V, individually addressable

1

HC-SR04 Ultrasonic Sensor

U2

$2-5

Standard HC-SR04 module

1

USB Cable (Micro-USB/USB-C)

—

$3-8

For programming and power

1

Jumper Wires (M-F, 10cm)

—

$2-5

Assorted pack

1

5V Power Supply (3A+)

PS1

$8-15

Optional, for full LED brightness

Total Estimated Cost

$33-68

Prices vary by region and supplier

Note

Budget Option: Start with just ESP32 + sensor + a few LEDs for initial testing. Add the full LED strip later when you’re ready for the complete display.

Hardware Assembly

Basic Assembly Steps

  1. Prepare Components

    • Identify all GPIO pins on ESP32 board

    • Check LED strip polarity (DIN, 5V, GND)

    • Verify HC-SR04 sensor pin labels (Trig, Echo, VCC, GND)

  2. Connect HC-SR04 Sensor

    • Trig → GPIO14

    • Echo → GPIO13

    • VCC → 5V

    • GND → GND

  3. Connect WS2812 LED Strip

    • DIN (Data In) → GPIO12

    • 5V/VCC → 5V (or external power supply)

    • GND → GND (common ground with ESP32)

  4. Power Considerations

    • USB Power Only: Connect ESP32 via USB, LED strip to ESP32 5V pin

    • External Power: Connect 5V supply to both ESP32 VIN and LED strip VCC, share GND

  5. Verify Connections

    • Double-check all pin assignments

    • Ensure common ground between all components

    • Check for loose connections

Safety Considerations

Warning

Electrical Safety:

  • Do not exceed 5V on ESP32 VIN or LED strip

  • Use proper gauge wires for high-current LED connections

  • External power supply should have short-circuit protection

  • Never connect/disconnect components while powered on

Note

Best Practices:

  • Use a breadboard for prototyping before permanent installation

  • Add a 100µF capacitor across LED strip power pins (reduces noise)

  • Keep sensor away from ultrasonic-interfering materials (foam, fabric)

  • Mount LED strip away from direct sunlight (improves visibility)

Next Steps

Hardware ready? Great! Now you can:

  1. Build the Firmware - See Quick Start Guide for build instructions

  2. Flash to ESP32 - Upload the firmware via USB

  3. Test the System - Verify sensor readings and LED display

  4. Configure WiFi - Access web interface for configuration

No hardware yet? No problem! Try QEMU Emulator Guide for full simulation.