Ultrasonic Parking Assistant

Project Overview

An intelligent parking assistance system using ultrasonic distance measurement and visual feedback. The system measures the distance to obstacles in real-time and provides graduated visual warnings through a series of LEDs that change color based on proximity.

This project demonstrates practical embedded systems development, combining sensor interfacing with real-time control logic to create a functional safety system suitable for garage installations or warehouse vehicle operations.

Raspberry Pi Compatibility

This project works with any Raspberry Pi model that has GPIO pins:

Raspberry Pi 5 (2023)
Raspberry Pi 4 Model B (2019)
Raspberry Pi 3 Model B+ / 3 Model B / 3 Model A+ (2016-2018)
Raspberry Pi 2 Model B (2015)
Raspberry Pi 1 Model B+ / Model A+ (2014)
Raspberry Pi Zero 2 W / Zero W / Zero (2015-2021)

Note: All models use the same 40-pin GPIO header layout, so the pin connections remain consistent across versions.

Components Used

Raspberry Pi (see Raspberry Pi Compatibility section below)
HC-SR04 Ultrasonic Distance Sensor
3x LEDs (Green, Yellow, Red)
3x 220Ω current-limiting resistors
Active buzzer module (optional)
Breadboard and jumper wires
Power supply (5V 2.5A minimum, 5V 3A recommended for Pi 3/4/5)
MicroSD card (8GB minimum)

Hardware Setup

Component	Component Pin	GPIO Pin	Physical Pin Number
HC-SR04	VCC	5V Power	Pin 2 or Pin 4
HC-SR04	TRIG	GPIO23	Pin 16
HC-SR04	ECHO	GPIO24	Pin 18
HC-SR04	GND	Ground	Pin 6, 9, 14, 20, 25, 30, 34, or 39
Green LED	Anode (+)	GPIO17	Pin 11
Yellow LED	Anode (+)	GPIO27	Pin 13
Red LED	Anode (+)	GPIO22	Pin 15
All LEDs	Cathode (-)	Ground (via 220Ω resistor)	Any Ground pin

Important: Each LED must have a 220Ω current-limiting resistor between the LED cathode and Ground. The GPIO pins are shown in BCM numbering format (used in the code).

Quick Summary: HC-SR04 connects to GPIO23 & GPIO24. LEDs connect to GPIO17 (Green), GPIO27 (Yellow), and GPIO22 (Red).

Key Features

Accurate distance measurement from 2cm to 400cm
Three-tier visual warning system (Green/Yellow/Red)
Configurable distance thresholds
Real-time continuous monitoring
Optional audible alarm for critical proximity
Low latency response (< 100ms)
Reliable operation in various lighting conditions

Software Implementation

Core distance measurement and LED control logic:

import RPi.GPIO as GPIO
import time

# Pin definitions
TRIG = 23
ECHO = 24
LED_GREEN = 17
LED_YELLOW = 27
LED_RED = 22

GPIO.setmode(GPIO.BCM)
GPIO.setup(TRIG, GPIO.OUT)
GPIO.setup(ECHO, GPIO.IN)
GPIO.setup(LED_GREEN, GPIO.OUT)
GPIO.setup(LED_YELLOW, GPIO.OUT)
GPIO.setup(LED_RED, GPIO.OUT)

def measure_distance():
    GPIO.output(TRIG, True)
    time.sleep(0.00001)
    GPIO.output(TRIG, False)
    
    while GPIO.input(ECHO) == 0:
        pulse_start = time.time()
    while GPIO.input(ECHO) == 1:
        pulse_end = time.time()
    
    duration = pulse_end - pulse_start
    distance = duration * 17150
    return round(distance, 2)

def update_leds(distance):
    if distance > 50:
        GPIO.output(LED_GREEN, True)
        GPIO.output(LED_YELLOW, False)
        GPIO.output(LED_RED, False)
    elif distance > 20:
        GPIO.output(LED_GREEN, False)
        GPIO.output(LED_YELLOW, True)
        GPIO.output(LED_RED, False)
    else:
        GPIO.output(LED_GREEN, False)
        GPIO.output(LED_YELLOW, False)
        GPIO.output(LED_RED, True)

try:
    while True:
        dist = measure_distance()
        update_leds(dist)
        print(f"Distance: {dist} cm")
        time.sleep(0.1)
except KeyboardInterrupt:
    GPIO.cleanup()

📥 Download Complete Python Code

Installation: No additional libraries required - uses built-in RPi.GPIO
Make executable with: chmod +x ultrasonic-parking-assistant.py

Distance Zones

Distance Range	Status	LED Indicator	Action
> 50 cm	Safe	Green LED	Continue approach
20-50 cm	Caution	Yellow LED	Slow down
< 20 cm	Danger	Red LED (+ Buzzer)	Stop immediately

Skills Demonstrated

Python Programming

GPIO Control

Sensor Integration

Real-time Processing

LED Circuit Design

Embedded Systems

Safety Systems

Hardware Interfacing

Technical Specifications

Measurement Range: 2cm - 400cm
Accuracy: ±3mm
Measuring Angle: 15 degrees
Ultrasonic Frequency: 40kHz
Update Rate: 10Hz (configurable)
Operating Voltage: 5V DC
Response Time: < 100ms

Practical Applications

Beyond parking assistance, this system can be adapted for various applications including warehouse automation for forklift safety, robotic obstacle avoidance, liquid level monitoring in tanks, automated door systems, security perimeter detection, and industrial material handling operations.