Project 1: Distance-Based LED Brightness Control

Distance-Based LED Brightness Control

Overview:

This project focuses on ultrasonic distance measurement and uses the measured distance to control an LED's brightness via PWM. It integrates Arduino for distance calculation and Red Pitaya for signal analysis of the ultrasonic echo and PWM waveform.

Objectives:

1. Measure the distance of an object using an ultrasonic sensor.
2. Map the distance to control LED brightness using PWM.
3. Use Red Pitaya to analyze the ultrasonic echo signal and PWM output.

Components:

Steps:

1. Circuit Assembly:

1. Connect the Ultrasonic Sensor:
• VCC to Arduino 5V.
• GND to Arduino GND.
• Trigger Pin to Arduino digital pin (e.g., pin 10).
• Echo Pin to Arduino digital pin (e.g., pin 9).
2. Connect the LED:
• One terminal to Arduino PWM pin (e.g., pin 11) through a 220 Ω resistor.
• The other terminal to GND.
3. For Red Pitaya:
• Connect the Echo Pin to Red Pitaya IN1 to capture the ultrasonic echo.
• Connect the PWM pin output to Red Pitaya IN2 to monitor the LED brightness signal.

2. Arduino Programming:

1. Write a program to measure distance and control LED brightness:
Copy

const int trigPin = 10;
const int echoPin = 9;
const int ledPin = 11;

void setup() {
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
    pinMode(ledPin, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    // Measure distance
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    long duration = pulseIn(echoPin, HIGH);
    long distance = duration * 0.034 / 2;

    // Map distance to LED brightness
    int brightness = map(distance, 0, 100, 0, 255);
    brightness = constrain(brightness, 0, 255);
    analogWrite(ledPin, brightness);

    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");
    delay(100);
}

3. Red Pitaya Signal Analysis:

1. Echo Signal:
• Connect the Echo Pin to IN1 and visualize the raw ultrasonic echo.
• Measure the time difference between trigger and echo signals.
2. PWM Signal:
• Connect the LED’s PWM pin to IN2 and analyze the duty cycle and frequency.
• Verify how brightness correlates with duty cycle.

Value:

1. Understand distance measurement and PWM-based brightness control.
2. Analyze real-world signals using Red Pitaya for debugging and optimization.