Project #3: Demonstrating PWM Now let’s try this with our circuit from Project 2. Enter the following sketch into the IDE and upload it to the Arduino: Project 3 - Demonstrating PWM int d = 5; void setup() { pinMode(3, OUTPUT); // LED control pin is 3, a PWM capable pin } void loop() { for ( int a = 0 ; a < 256 ; a++ ) { analogWrite(3, a); delay(d); } for ( int a = 255 ; a >= 0 ; a-- ) { analogWrite(3, a); delay(d); } delay(200); } .................................................................................................................................................................. The LED on digital pin 3 will exhibit a “breathing effect” as the duty cycle increases and decreases. In other words, the LED will turn on, increasing in brightness until fully lit, and then reverse. Experiment with the sketch and circuit. For example, make five LEDs breathe at once, or have them do so sequentially.
Project #2: Repeating with for Loops When designing a sketch, you’ll often repeat the same function. You could simply copy and paste the function to duplicate it in a sketch, but that’s inefficient and a waste of your Arduino’s program memory. Instead, you can use for loops. The benefit of using a for loop is that you can determine how many times the code inside the loop will repeat. To see how a for loop works, enter the following code as a new sketch: Project 2 - Repeating with for Loops int d = 100; void setup() { pinMode(2, OUTPUT); pinMode(3, OUTPUT); pinMode(4, OUTPUT); pinMode(5, OUTPUT); pinMode(6, OUTPUT); } void loop() { First Steps 47 for ( int a = 2; a < 7 ; a++ ) { digitalWrite(a, HIGH); delay(d); digitalWrite(a, LOW); delay(d); } } .................................................................................................................................................................. The for loop will repeat the code within th