ESP32 + VL53L1X Proximity Detector

📌 Pin Connection Guide for ZY-ESP32 / ESP32 DevKit V1:

ESP32 Connections:

• Pin 1 (3.3V): Power supply → Connect to VL53L1X power pins and pull-up resistors
• Pin 20 (GPIO21): I²C SDA data line → Connect to VL53L1X Pin 9
• Pin 23 (GPIO22): I²C SCL clock line → Connect to VL53L1X Pin 8
• Pin 11 (GPIO2): LED control → Connect to LED anode through 220Ω resistor
• Pin 19 or 25 (GND): Ground → Connect to all ground points

VL53L1X Sensor (497-17764-1-ND):

• Pin 1 (AVDD): Analog power → 3.3V
• Pin 2 (AVDDVCSEL): VCSEL laser power → 3.3V
• Pin 3 (GND): Ground → GND
• Pin 4 (AVSS): Analog ground → GND
• Pin 5 (IOVDD): I/O power → 3.3V
• Pin 6 (GPIO1): Not connected (leave floating)
• Pin 7 (XSHUT): Shutdown control → 3.3V (always enabled)
• Pin 8 (SCL): I²C clock → ESP32 GPIO22 with 10kΩ pull-up
• Pin 9 (SDA): I²C data → ESP32 GPIO21 with 10kΩ pull-up

LED Indicator Circuit:

• R3 (220Ω): Current limiting resistor for LED protection
• LED1: Any standard LED (Red recommended for visibility)
• Wiring: ESP32 GPIO2 → 220Ω Resistor → LED Anode (+, long leg) → LED Cathode (-, short leg) → GND
• Note: Your ESP32 has a built-in LED on GPIO2, so it will blink too!

🔧 Components List:

• U1: ESP32 DevKit V1 (ZY-ESP32 or compatible 30-pin board)
• U2: VL53L1X ToF Distance Sensor (Digi-Key part# 497-17764-1-ND)
• R1, R2: 10kΩ resistors (I²C pull-ups)
• R3: 220Ω resistor (LED current limiter)
• C1: 0.1µF ceramic capacitor (bypass)
• C2: 10µF electrolytic capacitor (bulk decoupling)
• LED1: Standard 5mm LED (any color, Red recommended)
• Breadboard and jumper wires

⚡ Quick Connection Summary:

• Power: ESP32 3.3V → VL53L1X Pins 1,2,5,7 + Pull-up resistors
• Ground: ESP32 GND → VL53L1X Pins 3,4 + LED cathode + Capacitors
• I²C SDA: ESP32 GPIO21 ↔ VL53L1X Pin 9 (with 10kΩ pull-up)
• I²C SCL: ESP32 GPIO22 ↔ VL53L1X Pin 8 (with 10kΩ pull-up)
• LED: ESP32 GPIO2 → 220Ω → LED(+) → LED(-) → GND

💡 How It Works:

• The VL53L1X sensor continuously measures distance using Time-of-Flight technology
• ESP32 reads distance data via I²C communication (address 0x29)
• When an object is detected within threshold distance (default 30cm), GPIO2 activates
• The external LED blinks rapidly to indicate proximity detection
• The onboard LED on GPIO2 also blinks simultaneously
• Serial monitor displays real-time distance measurements in millimeters

💻 Arduino Code Example:

#include <Wire.h>
#include <VL53L1X.h>

VL53L1X sensor;

#define LED_PIN 2           // GPIO2 - Built-in LED + External LED
#define THRESHOLD_DISTANCE 300  // 30cm in millimeters

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);  // SDA=GPIO21, SCL=GPIO22
  
  // Initialize LED pin
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  
  Serial.println("Proximity detector ready!");
  Serial.print("Detection threshold: ");
  Serial.print(THRESHOLD_DISTANCE);
  Serial.println(" mm");
  Serial.println();
}

void loop() {
  uint16_t distance = sensor.read();
  
  if (!sensor.timeoutOccurred()) {
    // Print distance to serial monitor
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.print(" mm | ");
    Serial.print(distance / 10.0, 1);
    Serial.print(" cm");
    
    // Check if object is within threshold and blink LED
    if (distance < THRESHOLD_DISTANCE) {
      Serial.println(" ⚠️  OBJECT DETECTED!");
      
      // Blink LED rapidly
      digitalWrite(LED_PIN, HIGH);
      delay(100);
      digitalWrite(LED_PIN, LOW);
      delay(100);
    } else {
      Serial.println();
      digitalWrite(LED_PIN, LOW);
    }
  } else {
    Serial.println("⚠️  TIMEOUT");
  }
  
  delay(50);
}

📚 Library Installation:

• Step 1: Open Arduino IDE
• Step 2: Go to Sketch → Include Library → Manage Libraries
• Step 3: Search for "VL53L1X"
• Step 4: Install "VL53L1X by Pololu"
• Step 5: Select board: Tools → Board → ESP32 Arduino → ESP32 Dev Module
• Step 6: Select correct COM port: Tools → Port
• Step 7: Upload the code!

🔍 Troubleshooting:

• Sensor not detected:
  • Check all power connections (3.3V NOT 5V!)
  • Verify I²C pull-up resistors are installed
  • Run I²C scanner to check address 0x29
  • Ensure XSHUT pin is connected to 3.3V
• LED not blinking:
  • Check LED polarity (long leg = anode = positive)
  • Verify 220Ω resistor is in series with LED
  • Test GPIO2 with a simple blink sketch first
• Erratic readings:
  • Add capacitors close to sensor power pins
  • Keep sensor away from bright lights or IR sources
  • Avoid highly reflective or transparent surfaces
  • Ensure stable 3.3V power supply
• Upload errors:
  • Hold BOOT button while uploading (if needed)
  • Check USB cable supports data transfer
  • Install CH340 or CP2102 USB drivers if needed

⚙️ Customization Options:

• Change detection distance: Modify THRESHOLD_DISTANCE (in mm)
• Adjust blink speed: Change delay values in the if statement
• Solid LED instead of blink: Remove the delay and LOW commands
• Different distance modes:
  • VL53L1X::Short - Up to 1.3m (best accuracy)
  • VL53L1X::Medium - Up to 3m (balanced)
  • VL53L1X::Long - Up to 4m (maximum range)
• Add buzzer: Connect to another GPIO for audio alerts
• Multiple LEDs: Use different colors for different distance ranges

⚠️ Important Notes:

• NEVER use 5V! The VL53L1X requires 3.3V only
• I²C address is 0x29 (fixed, not changeable via hardware)
• Maximum I²C clock speed: 400 kHz
• Sensor measures from 4cm to 4 meters
• GPIO2 has a built-in LED on most ESP32 boards
• Place decoupling capacitors as close to sensor as possible
• The sensor uses an infrared laser (Class 1 - safe for eyes)

🎯 Next Steps:

• Test with different objects and surfaces
• Experiment with different threshold distances
• Add WiFi connectivity for remote monitoring
• Create a web interface to display distance data
• Add an OLED display for standalone operation
• Build a parking sensor or obstacle detector
• Implement data logging to SD card