Question

Problem 2 (50 points) One common method of outputting an "effective" analog signal is to use pulse width modulation or PWM. In this modulation scheme, a high frequency square wave is switched on and off with a duty cycle determined by the desired output intensity, where Duty Cycle = Time spend "on" Total period 50% duty cycle 75% duty cycle 25% duty cycle As an example, an LED lit with a PWM signal at 50% duty cycle would appear approximately half as bright as the same LED that was lit continuously. However, in order for the effect to be convincing, the

It's an Energia sketch using C language. We work with MSP430 Launchpad but you shouldn't need it to write the code.

I'm really stuck :(

Answer 1

Please check the code. It is compiling successfully. I hope it works fine on Arduino or MSP430 launchpad. The code has been written with Arduino in mind. All the necessary comments are there for easy understanding. And Modify it accordingly if anything needs to be changed. Thanks :)

CODE:

//PIN declarations for input buttons and output LED. Change these according to your circuit connections
int Button1 = 8;   
int Button2 = 9;
int ledPin = 11;

//VARIABLES REQUIRED FOR DEBOUNCING
boolean last1=LOW;
boolean last2=LOW;
boolean current1 = LOW;
boolean current2 = LOW;

boolean state = HIGH; //TO know ON/OFF state of led

//LED LEVELS FOR 3 DIFFERENT INTENSITIES
int low = 50;
int med = 150;
int high = 255;

int ledLevel = med; // Default level on starting is medium
int lastLevel = med; //To store the last ON-level of LED before switching it OFF by button2

String str = ""; //To check Keyboard Control and Button Control

void setup(){
Serial.begin(9600);
pinMode(Button1,INPUT);
pinMode(Button2,INPUT);
pinMode(ledPin,OUTPUT);
analogWrite(ledPin,ledLevel);
}

void changeBrightness(){
if(ledLevel == low){
ledLevel = med;
}
else if(ledLevel == med){
ledLevel = high;
}
else if(ledLevel == high){
ledLevel = low;
}
}

void buttonControl(){
current1=digitalRead(Button1);
current2=digitalRead(Button2);
  
if(last1 != current1){ //CHECKING BUTTON-1
delay(5); //DEBOUNCING DELAY
current1=digitalRead(Button1);
if(state == HIGH && current1== HIGH && last1 == LOW)
{
changeBrightness();
analogWrite(ledPin,ledLevel);
last1 = current1;
}
}
  
if(last2 != current2){ //CHECKING BUTTON-2
delay(5); //DEBOUNCING DELAY
current2=digitalRead(Button2);

if(current2== HIGH && last2 == LOW){
if(state == HIGH){
lastLevel = ledLevel;
ledLevel = 0;
state = LOW;
}
else{
ledLevel = lastLevel;
state = HIGH;
}
analogWrite(ledPin,ledLevel);
last2 = current2;
}
}
}

void keyboardControl(){
String s = "";
while(Serial.available()>0){
s = Serial.readString();
}
  
if(state == HIGH && s == "Change Brightness"){   
changeBrightness();
}
  
else if(state == HIGH && s == "TURN OFF"){   
lastLevel = ledLevel;
ledLevel = 0;
state = LOW;
}
else if(state == LOW && s == "TURN ON"){
ledLevel = lastLevel;
state = HIGH;
}
analogWrite(ledPin,ledLevel);   
  
}

void loop(){
while(!Serial.available()){
buttonControl();
}
str = Serial.readString();
while(str == "Keyboard Control"){
keyboardControl();
if(Serial.available()){
if(Serial.readString()== "Button Control"){
str = "Button Control";
}
}
}
}