Short-Range Radar System 

Components

This ultrasonic sensor works in the air for non-contact object detection within an area. This sensor is not affected by a color or other visual characteristics of the detected object. Ultrasonic sensors use high-frequency sound to detect and localize objects in a variety of environments. Ultrasonic sensors measure the time of flight for sound that has been transmitted to and reflected from nearby objects.  Based on the time of flight, the sensor then outputs a range reading.

Pin 5-TX- When the *BW is open or held low, the TX output delivers asynchronous serial with an RS232 format, except voltages are 0-Vcc. The output is an ASCII capital “R”, followed by three ASCII character digits representing the range in inches up to a maximum of 255, followed by a carriage return (ASCII 13). The baud rate is 9600, 8 bits, no parity, with one stop bit. Although the voltage of 0-Vcc is outside the RS232 standard, most RS232 devices have sufficient margin to read 0-Vcc serial data. If standard voltage level RS232 is desired, invert, and connect an RS232 converter such as a MAX232. When the BW pin is held high the TX output sends a single pulse, suitable for low noise chaining (no serial data).

Pin 6- Vcc (+5V)  - Operates on 2.5V - 5.5V. Recommended current capability of 3mA for 5V, and 2mA for 3V. Please reference page 4 for minimum operating voltage versus temperature information.

Sensor Minimum Distance and Range "0" Location

The LV-MaxSonar-EZ sensor measures the distance to objects starting from the front of the sensor, as illustrated in the diagram below. Typically, the LV-MaxSonar-EZ reports the distance to the leading edge of the nearest detectable object. The sensor's ability to detect targets has been characterized and illustrated in its beam patterns.

Sensor Minimum Distance

The sensor minimum reported distance is 6-inches (15.2 cm). However, the LV-MaxSonar-EZ will range and report targets to the front sensor face. Large targets closer than 6 inches will typically range from 6 inches. 

3. Arduino UNO:

   - Microcontroller: The Arduino UNO serves as the main controller for the radar system, processing data from the ultrasonic sensor and controlling the servo motor.

4. Jumper Wires:

   - Connections: These are used to connect the various components to the Arduino board.

5. Optional Motor Shield:

   - Enhanced Control: While optional, a motor shield can simplify the control of the servo motor by providing dedicated motor control pins and additional power options.

Circuit Diagram

The circuit for this project can be constructed using an Arduino UNO without a motor shield, as the current requirement of the SG90 servo motor is very low. However, as a good practice, it is recommended to use motor drivers to control motors connected to the Arduino, especially if the project is upgraded with additional components.

Arduino Current Limitations

• Powered by USB: Total of 500mA

• With External Power Supply: Total of 500mA to 1A

• 5V Pin: 500mA or 500mA to 1A

• Each Input/Output Pin: 40mA

• The sum of All Input/Output Pins Combined: 200mA

Due to these current limitations, using a motor driver (as shown in the figure, Option 2) is recommended for projects that may include additional gadgets. However, if a motor shield is not available, the circuit can be connected as shown in the figure below (Option 1).

The following video shows the complete development and testing of an Arduino-based radar system using the MaxSonar EZ-1 ultrasonic sensor. The demonstration covers the following key aspects:

• Arduino Radar DEMO

• Arduino Code

• Processing Code

• Test Results

• Arduino Radar DEMO

Arduino Code

The video then transitions to an overview of the Arduino code that controls the radar system. Key points covered include:

• Initialization: The code begins by initializing the servo motor and ultrasonic sensor.

• Servo Control: Functions to rotate the servo motor from 0 to 180 degrees in increments, allowing the sensor to sweep the area.

• Distance Measurement: Code to trigger the ultrasonic sensor and read the time of flight for the sound waves.

• Data Processing: Calculation of distance based on the time of flight and storing the results.

• Serial Communication: Sending distance data to the computer via serial communication for further processing.

• The video highlights specific portions of the code, explaining how each part contributes to the overall functionality of the radar system.

Processing Code

Following the Arduino code, the video demonstrates the Processing code used for visualizing the radar data. The key features include:

• Serial Data Reading: The Processing sketch reads the distance data sent from the Arduino via the serial port.

• Graphical Interface: A graphical user interface (GUI) is created to display the radar data in a visual format.

• Real-time Visualization: As the servo motor sweeps, the Processing sketch plots the detected distances on a radar-like display, showing the position and distance of objects relative to the sensor.

The video walks through the Processing code, explaining how the data is read and visualized, and how the interface updates in real-time to reflect the sensor readings.

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