Arduino for beginners

// Change the brightness of the LED

int ledPin = 9; // LED connected to this pin
void setup () {
  pinMode (ledPin, OUTPUT); // initialize the pin to output
}

void loop () {
  analogWrite (ledPin, 255); // full brightness (255/255 = 1)
  delay (1000); // pause 1 sec
  digitalWrite (ledPin, LOW); // turn off the LED
  delay (1000); // pause 1 sec

  analogWrite (ledPin, 191); // brightness at 3/4 (191/255 ~ = 0.75)
  delay (1000); // pause 1 sec
  digitalWrite (ledPin, LOW); // turn off the LED
  delay (1000); // pause 1 sec

  analogWrite (ledPin, 127); // half brightness (127/255 ~ = 0.5)
  delay (1000); // pause 1 sec
  digitalWrite (ledPin, LOW); // turn off the LED
  delay (1000); // pause 1 sec

  analogWrite (ledPin, 63); // quarter brightness (63/255 ~ = 0.25)
  delay (1000); // pause 1 sec
  digitalWrite (ledPin, LOW); // turn off the LED
  delay (1000); // pause 1 sec
}

analogWrite (ledPin, brightness);
delay (5); // short delay
brightness = brightness + 1;

for (int brightness = 0; brightness = 0; brightness -) {

analogWrite (ledPin, brightness);
delay (5);

}

// smoothly change the brightness

int ledPin = 9; // LED is connected to this pin

void setup () {
  pinMode (ledPin, OUTPUT); // initialize the pin to exit
}

void loop () {
  // gradually increase the brightness (0 to 255)
  for (int brightness = 0; brightness = 0; brightness -) {
    analogWrite (ledPin, brightness);
    delay (5);
  }

  delay (1000); // wait 1 sec
 // smoothly decrease the brightness (255 to 0)
  for (int brightness = 255; brightness> = 0; brightness -) {
    analogWrite (ledPin, brightness);
    delay (5);
  }

  delay (1000); // wait 1 sec
}
}

  Sketch modeling

// RGB LED - test

// pin connections
int red = 9;
int green = 10;
int blue = 11;

void setup () {
  pinMode (red, OUTPUT);
  pinMode (blue, OUTPUT);
  pinMode (green, OUTPUT);
}

void loop () {
  // turn on / off the red LED
  digitalWrite (red, HIGH);
  delay (500);
  digitalWrite (red, LOW);
  delay (500);
  
  // turn on / off the green LED
  digitalWrite (green, HIGH);
  delay (500);
  digitalWrite (green, LOW);
  delay (500);

  // turn on / off the blue LED
  digitalWrite (blue, HIGH);
  delay (500);
  digitalWrite (blue, LOW);
  delay (500);
}

// RGB LED - random colors

// pin connections
int red = 9;
int green = 10;
int blue = 11;
void setup () {
  pinMode (red, OUTPUT);
  pinMode (blue, OUTPUT);
  pinMode (green, OUTPUT);
}
void loop () {
  // pick a random color
  analogWrite (red, random (256));
  analogWrite (blue, random (256));
  analogWrite (green, random (256));
  delay (1000); // wait one second
}

int multiplier (int number1, int number2) {

int product = number1 * number2;
return product;

} 

Button

In the next sketch, a button with normally open contacts will be used, without fixing.

This means that while the button is not pressed, the current does not flow through it, and after releasing, the button returns to its original position.
In the circuit, in addition to the button, a resistor is used. In this case, it does not limit the current, but "pulls" the button to 0v (GND). Those. until the button is pressed on the pin of the Arduino to which it is connected, the level will be low. The resistor used in the 10 kΩ circuit.

// define the button click
int buttonPin = 7;
void setup () {
  pinMode (buttonPin, INPUT); // initialize the input pin
  Serial.begin (9600); // initialize the serial port
}
void loop () {
  if (digitalRead (buttonPin) == HIGH) {// if the button is pressed
    Serial.println ("pressed"); // print "pressed"
  } else {
    Serial.println ("unpressed"); // otherwise "unpressed"
  }
}

There are several new teams in this sketch.
-This command takes the value High (high level) and low (low level) of the output that we are checking. Previously, in setup (), this output must be configured for input.
; // where buttonPin is the pin number where the button is connected.
The serial port allows you to send Arduino messages to the computer, while the controller itself runs the program. This is useful for debugging a program, sending messages to other devices or applications. To enable data transfer via the serial port (also known as UART or USART), you must initialize it in setup ()

Serial.begin () has only one argument is the data transfer rate between the Arduino and the computer.
sketch, a command is used to display a message on the screen in the Arduino IDE (Tools >> Serial Monitor).
- the design allows you to control the progress of the program by combining several checks in one place.
If (if) digitalRead returns HIGH, then the word "pressed" is displayed on the monitor. Else (otherwise) the word "squeezed" is displayed on the monitor. Now you can try turning the LED on and off at the touch of a button.

// button press detection with LED output
int buttonPin = 7;
int ledPin = 8;
void setup () {
  pinMode (buttonPin, INPUT); // this time we will set button pin as INPUT
  pinMode (ledPin, OUTPUT);
  Serial.begin (9600);
}
void loop () {
  if (digitalRead (buttonPin) == HIGH) {
    digitalWrite (ledPin, HIGH);
    Serial.println ("pressed");
  } else {
    digitalWrite (ledPin, LOW);
    Serial.println ("unpressed");
  }
}

  Sketch modeling

Analog input.

analogRead allows you to read data from one of the Arduino analog pins and displays a value in the range from 0 (0V) to 1023 (5V). If the voltage at the analog input is 2.5V, then 2.5 / 5 * 1023 = 512 will be printed
analogRead has only one argument- This is the analog input number (A0-A5). The following sketch provides a code for reading voltage from a potentiometer. To do this, connect a variable resistor, the extreme pins to pins 5V and GND, and the middle pin to input A0.

Run the following code and look in the serial monitor how the values ​​change depending on the rotation of the resistor knob.

// analog input

int potPin = A0; // the central output of the potentiometer is connected to this pin

void setup () {
  // the analog pin is enabled by input by default, so initialization is not needed
  Serial.begin (9600);
}

void loop () {
  int potVal = analogRead (potPin); // potVal is a number between 0 and 1023
  Serial.println (potVal);
}

The next sketch combines a button-click sketch and a LED brightness control sketch. The LED will turn on from the button, and the potentiometer will control the brightness of the glow.

// button press detection with LED output and variable intensity
int buttonPin = 7;
int ledPin = 9;
int potPin = A0;
void setup () {
  pinMode (buttonPin, INPUT);
  pinMode (ledPin, OUTPUT);
  Serial.begin (9600);
}
void loop () {
  if (digitalRead (buttonPin) == HIGH) {// if button pressed
    int analogVal = analogRead (potPin);
    int scaledVal = map (analogVal, 0, 1023, 0, 255);
    analogWrite (ledPin, scaledVal); // turn on led with intensity set by pot
    Serial.println ("pressed");
  } else {
    digitalWrite (ledPin, LOW); // turn off if button is not pressed
    Serial.println ("unpressed");
  }
}