Building an Ultrasonic Radar using Arduino and Processing

1#include <Servo.h>
2
3// --- Pin Definitions ---
4const int SERVO_PIN = 11;
5const int TRIG_PIN = 8;
6const int ECHO_PIN = 9;
7
8// --- Constants for Servo ---
9const int MIN_ANGLE = 0;
10const int MAX_ANGLE = 180;
11const int ANGLE_STEP = 1;
12const int SWEEP_DELAY = 15; // Delay between servo movements in milliseconds
13
14// --- Constants for Ultrasonic Sensor ---
15// The speed of sound is 343 m/s or 29.1 microseconds per centimeter.
16// The pulseIn() function measures the round trip time.
17// So, the distance in cm is (duration / 2) / 29.1 = duration / 58.2
18const float SOUND_SPEED_FACTOR = 58.2; 
19
20Servo myServo;
21
22void setup() {
23  pinMode(TRIG_PIN, OUTPUT);
24  pinMode(ECHO_PIN, INPUT);
25  myServo.attach(SERVO_PIN);
26  Serial.begin(9600);
27}
28
29void loop() {
30  // Sweep from MIN_ANGLE to MAX_ANGLE
31  sweepAndMeasure(MIN_ANGLE, MAX_ANGLE, ANGLE_STEP);
32  
33  // Sweep back from MAX_ANGLE to MIN_ANGLE
34  sweepAndMeasure(MAX_ANGLE, MIN_ANGLE, -ANGLE_STEP);
35}
36
37/**
38 * @brief Sweeps the servo motor and measures the distance at each step.
39 * @param startAngle The starting angle of the sweep.
40 * @param endAngle The ending angle of the sweep.
41 * @param step The increment or decrement for the angle.
42 */
43void sweepAndMeasure(int startAngle, int endAngle, int step) {
44  for (int angle = startAngle; (step > 0) ? (angle <= endAngle) : (angle >= endAngle); angle += step) {
45    myServo.write(angle);
46    delay(SWEEP_DELAY);
47    int distance = calculateDistance();
48    printData(angle, distance);
49  }
50}
51
52/**
53 * @brief Calculates the distance using the ultrasonic sensor.
54 * @return The calculated distance in centimeters.
55 */
56int calculateDistance() {
57  // Trigger the ultrasonic sensor
58  digitalWrite(TRIG_PIN, LOW);
59  delayMicroseconds(2);
60  digitalWrite(TRIG_PIN, HIGH);
61  delayMicroseconds(10);
62  digitalWrite(TRIG_PIN, LOW);
63
64  // Read the echo pulse
65  long duration = pulseIn(ECHO_PIN, HIGH);
66
67  // Calculate the distance in centimeters
68  return static_cast<int>(duration / SOUND_SPEED_FACTOR);
69}
70
71/**
72 * @brief Prints the angle and distance data to the Serial Monitor.
73 * @param angle The current angle of the servo.
74 * @param distance The measured distance.
75 */
76void printData(int angle, int distance) {
77  Serial.print(angle);
78  Serial.print(",");
79  Serial.print(distance);
80  Serial.print(".");
81}

1# Processing (Python) code for a Radar Display
2# This script reads angle and distance data from an Arduino over the serial port
3# and visualizes it as a classic radar screen.
4#
5# MODIFIED to use a rectangular, half-screen layout.
6
7add_library('serial')
8
9# --- Global Variables ---
10serial_port = None      # The serial port object
11font = None             # Font for displaying text
12in_string = ""          # String to buffer data from serial
13
14# CHANGED: Use rectangular screen dimensions
15screen_width = 800
16screen_height = 450 # Half the original height with some padding
17
18# Radar screen properties
19radar_radius = 350
20# CHANGED: Center coordinates are now relative to the new rectangular screen
21radar_center_x = screen_width / 2
22# Position the radar's baseline near the bottom of the window
23radar_center_y = screen_height - 100 
24
25# Data from Arduino
26current_angle = 0
27current_distance = 0
28
29# Data storage for drawing points
30point_history = []
31
32def setup():
33    """
34    This function runs once when the program starts.
35    It sets up the display window, initializes the serial communication,
36    and loads the font.
37    """
38    global serial_port, font
39
40    # --- Window and Graphics Setup ---
41    # CHANGED: Use the new rectangular dimensions
42    size(screen_width, screen_height)
43    smooth()
44
45    # Create a font for text display.
46    font = createFont("Monospaced", 20)
47    textFont(font)
48
49    # --- Serial Communication Setup ---
50    print("Available Serial Ports:")
51    print(Serial.list())
52
53    # ---!!! IMPORTANT: YOU MUST USE THE CORRECT PORT NAME !!!---
54    port_name = "/dev/cu.usbmodem11101"
55    
56    try:
57        print("Connecting to port: {}".format(port_name))
58        serial_port = Serial(this, port_name, 9600)
59        serial_port.clear()
60        
61    except Exception as e:
62        print("Error opening serial port: {}".format(e))
63        print("Please make sure the port name is correct and the Arduino is plugged in.")
64        print("Also ensure the Arduino IDE's Serial Monitor is closed.")
65        exit()
66
67
68def draw():
69    """
70    This function runs continuously in a loop, redrawing the screen
71    in each frame.
72    """
73    global current_angle, current_distance
74    background(0, 20, 0)
75    draw_radar_grid()
76    draw_text_labels()
77    draw_sweep_line(current_angle)
78    draw_detected_points()
79    update_and_draw_history()
80
81
82def draw_radar_grid():
83    """Draws the concentric semi-circles and lines of the radar."""
84    stroke(0, 150, 0)
85    noFill()
86    strokeWeight(2)
87
88    # Draw 2 concentric semi-circles for the top-half display
89    for i in range(1, 3):
90        radius = i * (radar_radius / 2.0)
91        # Use arc() to draw only the top half of the circle (from PI to TWO_PI)
92        arc(radar_center_x, radar_center_y, radius * 2, radius * 2, PI, TWO_PI)
93
94    # Draw the horizontal closing line for the semi-circle display
95    line(radar_center_x - radar_radius, radar_center_y, radar_center_x + radar_radius, radar_center_y)
96
97    # Draw 5 radial lines for the 180-degree sweep (left-to-right)
98    for i in range(5):
99        angle = radians((i * 45) - 180) 
100        x2 = radar_center_x + radar_radius * cos(angle)
101        y2 = radar_center_y + radar_radius * sin(angle)
102        line(radar_center_x, radar_center_y, x2, y2)
103
104
105def draw_text_labels():
106    """Displays text information on the screen."""
107    fill(0, 200, 0)
108    noStroke()
109    # Label the 2 rings along the horizontal axis
110    for i in range(1, 3):
111        radius_text = i * (radar_radius / 2.0)
112        text(str(i * 10) + " cm", radar_center_x + radius_text + 5, radar_center_y - 5)
113        
114    text("Angle: {} deg".format(current_angle), 20, 40)
115    text("Distance: {} cm".format(current_distance), 20, 70)
116    text("Radar Display", width / 2 - 80, 40)
117
118
119def draw_sweep_line(angle):
120    """Draws the moving line that sweeps across the radar."""
121    stroke(0, 255, 0, 150)
122    strokeWeight(3)
123    rad_angle = radians(angle - 180) 
124    end_x = radar_center_x + radar_radius * cos(rad_angle)
125    end_y = radar_center_y + radar_radius * sin(rad_angle)
126    line(radar_center_x, radar_center_y, end_x, end_y)
127
128
129def draw_detected_points():
130    """Draws a point on the radar for the current detection."""
131    max_dist = 20.0 
132    if current_distance > 0 and current_distance < max_dist:
133        stroke(255, 0, 0)
134        strokeWeight(5)
135        rad_angle = radians(current_angle - 180)
136        mapped_dist = map(current_distance, 0, max_dist, 0, radar_radius)
137        point_x = radar_center_x + mapped_dist * cos(rad_angle)
138        point_y = radar_center_y + mapped_dist * sin(rad_angle)
139        point(point_x, point_y)
140        point_history.append({'x': point_x, 'y': point_y, 'age': 255})
141
142def update_and_draw_history():
143    """Draws and fades out old points to create a trail effect."""
144    global point_history
145    new_history = []
146    for p in point_history:
147        stroke(0, p['age'], 0)
148        strokeWeight(4)
149        point(p['x'], p['y'])
150        p['age'] -= 2
151        if p['age'] > 0:
152            new_history.append(p)
153    point_history = new_history
154
155
156def serialEvent(port):
157    """
158    This function is automatically called by Processing whenever new data is available.
159    """
160    global in_string, current_angle, current_distance
161
162    while port.available() > 0:
163        in_char = port.readChar()
164        if in_char == '.':
165            values = in_string.split(',')
166            if len(values) == 2:
167                try:
168                    angle = int(values[0])
169                    distance = int(values[1])
170                    current_angle = angle
171                    current_distance = distance
172                except ValueError:
173                    pass
174            in_string = ""
175        else:
176            if in_char != '\n' and in_char != '\r':
177                in_string += in_char