Obstacle detection system using HC-SR04, SSD1306 screen and ESP32 board

ESP32 22-02-24

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Tutorial plan

1- Principle of obstacle detection system using HC-SR04, SSD1306 screen and ESP32 board

2- Necessary system components

3- Obstacle detection system wiring diagram

4- Programming the ESP32 board board with MicroPython

Principle of obstacle detection system using HC-SR04, SSD1306 screen and ESP32 board

An obstacle detection system is a technology designed to identify and alert users or autonomous systems about obstacles or hazards in their environment. These systems are commonly used in various applications, including robotics, autonomous vehicles, drones, industrial automation, and assistive technologies. The primary goal is to enhance safety and prevent collisions by providing real-time information about the presence of obstacles.

The obstacle detection system using HC-SR04, SSD1306 screen, LED, buzzer, and ESP32 board operates based on the principles of ultrasonic distance measurement and sensor integration. Here’s a step-by-step explanation of how the system works:

1- Ultrasonic Distance Measurement (HC-SR04):

The HC-SR04 ultrasonic sensor emits ultrasonic waves using the transducer on the trigger pin.

The waves travel through the air and bounce off any obstacle in their path.

The transducer on the echo pin receives the reflected waves.

2- Calculation of Distance:

The ESP32 board measures the time it takes for the ultrasonic waves to travel to the obstacle and back.

Using the speed of sound in air (approximately 343 meters per second), the ESP32 board calculates the distance to the obstacle.

3- Obstacle Detection:

A conditional statement checks if the measured distance is less than a predefined threshold (e.g., 20 cm).

If the distance is less than the threshold, an obstacle is considered detected.

4- Display on SSD1306 screen:

The SSD1306 screen serves as a user interface by displaying relevant information obstacle detection status.

5- LED Indication:

An LED is used to provide a visual indication of obstacle detection.

The LED is turned on when an obstacle is detected and turned off otherwise.

6- Buzzer Alert:

A buzzer is employed to provide an audible alert when an obstacle is detected.

The buzzer is activated, producing a tone, when the system identifies an obstacle.

Necessary system components

ESP32 board:

ESP32 card

The ESP32 is a powerful microcontroller developed by Espressif Systems. It’s renowned for its integrated Wi-Fi and Bluetooth capabilities, making it a popular choice for various IoT (Internet of Things) applications.

HC-SR04 ultrasonic Sensor

HC-SR04

The HC-SR04 is an ultrasonic distance measuring sensor module.

SSD1306 screen

The SSD1306 is a popular display controller used in OLED (Organic Light-Emitting Diode) screens. It’s commonly employed in various electronics projects to showcase information on small screens. The SSD1306 controller is compatible with different screen sizes and is often integrated with microcontrollers like Arduino UNO board to display text, graphics, and images.

This screen is used for displaying a alert message if the HC-SR04 sensor detects an obstacle.

LED

In an obstacle detection system, an LED (Light Emitting Diode) can be used as a visual indicator to provide feedback about the detection status. The LED can be programmed to turn on or off based on whether an obstacle is detected within a certain range.

Resistance (220 ohm)

The resistance needed for an LED (Light Emitting Diode) in a circuit is determined by Ohm’s Law, which states that the resistance (R) is equal to the voltage (V) divided by the current (I).

Jumper Wires:

Jumper wires

For making temporary connections and wiring between components.

Breadboard:

Test plate

A breadboard is a useful tool for creating temporary electronic circuits. It allows you to connect components without soldering.

Mounting the obstacle detection system controlled by ESP32 board

Attaching the SSD1306 screen :

– connect the VCC pin of the display to 5V pin of the ESP32 board

– connect the GND pin of the display to GND pin of the ESP32 board

– connect the SDA pin of the display to GPIO21 pin of the ESP32 board

– connect the SCL pin of the display to GPIO22 pin of the ESP32 board

Attaching the HC-SR04 sensor :

– Connect the VCC(+) pin of the HC-SR04 ultrasonic sensor to the 3.3V pin on the ESP32 board.

– Connect the Trig pin of the HC-SR04 ultrasonic sensor to GPIO16 pin on the ESP32 board.

– Connect the Echo pin of the HC-SR04 ultrasonic sensor to GPIO 17 pin on the ESP32 board.

– Connect the GND(-) pin of the DHT22 sensor to any ground (GND) pin on the ESP32 board.

Attaching the buzzer :

– Connect the (+) terminal of buzzer to GPIO23 pin on the ESP32 board.

– Connect the (-) terminal of buzzer to GND pin on the ESP32 board.

Attaching the red LED :

– Connect the negative terminal (cathode) of each LED to the ground (GND) of the ESP32 board.

– Connect a resistor between the GPIO19 pin and the positive terminal (anode) of the LED

Programming the ESP32 board board with MicroPython

To program an obstacle detection system using HC-SR04, a buzzer, an LED, and an ESP32 with Micropython, you’ll need to follow these steps.

1- Make sure you have Micropython installed on your ESP32 board.

2- Flash your ESP32 with MicroPython using this file esp32-20210902-v1.17.bin.

3- import this library : hc-sr04 for HC-SR04 sensor

4- import this library :ssd1306.py for SSD1306 screen

5- Create a new Python script and write the following code :

import machine
from machine import Pin, I2C
from hcsr04 import HCSR04
import ssd1306
import time

# Configure SSD1306 screen
i2c = I2C(-1, scl=Pin(22), sda=Pin(21))
oled_width = 128
oled_height = 64
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)
# Configure HC-SR04 pins
sensor = HCSR04(trigger_pin=16,echo_pin=17,echo_timeout_us=1000000)
# Configure red led pin
redled_pin=Pin(19, Pin.OUT)
# Configure buzzer pin
buzzer_pin=Pin(23, Pin.OUT)

while True:
 #calculate distance between the HC-SR04 sensor and an obstacle
 distance = sensor.distance_cm() 
 print('distance= ',distance,' cm')
 if (distance<4): # Check if obstacle is detected
  # Activate buzzer and LED
  redled_pin.value(1) 
  buzzer_pin.value(1)
  # show alert message on SSD1306 display
  oled.text('Attention!!!', 0, 0)
  oled.text('Obstacle', 0, 20)
  oled.text('detected', 0, 40)  
  oled.show()
 else:
  # Disable buzzer and LED
  redled_pin.value(0) 
  buzzer_pin.value(0)
  #clear SSD1306 screen
  oled.fill(0)
  oled.show()
 time.sleep_ms(100)

import machine

from machine import Pin, I2C

from hcsr04 import HCSR04

import ssd1306

import time

# Configure SSD1306 screen

i2c = I2C(-1, scl=Pin(22), sda=Pin(21))

oled_width = 128

oled_height = 64

oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)

# Configure HC-SR04 pins

sensor = HCSR04(trigger_pin=16,echo_pin=17,echo_timeout_us=1000000)

# Configure red led pin

redled_pin=Pin(19, Pin.OUT)

# Configure buzzer pin

buzzer_pin=Pin(23, Pin.OUT)

while True:

#calculate distance between the HC-SR04 sensor and an obstacle

distance = sensor.distance_cm()

print('distance= ',distance,' cm')

if (distance<4): # Check if obstacle is detected

# Activate buzzer and LED

redled_pin.value(1)

buzzer_pin.value(1)

# show alert message on SSD1306 display

oled.text('Attention!!!', 0, 0)

oled.text('Obstacle', 0, 20)

oled.text('detected', 0, 40)

oled.show()

else:

# Disable buzzer and LED

redled_pin.value(0)

buzzer_pin.value(0)

#clear SSD1306 screen

oled.fill(0)

oled.show()

time.sleep_ms(100)

Explanation of the program

If the HC-SR04 ultrasonic sensor detects an obstacle, the ESP32 board turns on the LED, sounds the buzzer and displays an alert message on the SSD1306. Otherwise, the ESP32 board turns off the LED, stops the buzzer and clears the alert message.