WARNING: If you follow the instructions, then playing about with the GPIO pins is safe and fun. Randomly plugging wires and power sources into your Pi, however, may destroy it, especially if using the 5V pins.

Lighting the LED with PYTHON

LEDs are delicate electronics components so if you put too much current through them they will be burned so to limit the current going through the LED, we should always use a resistor in series with it. We Try connecting the long leg of an LED to the Pi’s 3V3 and the short leg to a GND pin. The resistor can be anything over about 50Ω.

The LED should light up. It will always be on, because it’s connected to a 3V3 pin, which is itself always on. Now we move it from 3V3 to GPIO pin 17:

3rd Exercise :

THE PROGRAMS

Code it with python, blinking the LED on and off we used the GPIO Zero library which provides a simple interface to every GPIO components. It comes installed by default in Raspbian so we openned the IDLE (Python’s Integrated Development Environment) so for open it, we went to the menu and choose Programming. You should see two versions of IDLE so we choosed : Python 3.

1. First we made was type this 2 commands line :

from gpiozero import LED
led = LED(17)

2. Later, we Pressed Enter at the keyboard.

3. To make the LED switch on we typed the following and pressed Enter too:

led.on()

3. To make the LED switch of we typed the following and pressed Enter too:

led.off()

Now we have the first programm so we save as a file called : led.py

4th Exercise :

1. The idea is to make the basic blinking example present in any programming language so we wrote this :

from gpiozero import LED
from time import sleep

led = LED(17)

while True:
    led.on()
    sleep(1)
    led.off()
    sleep(1)

and of course we save as a new code

5th Exercise :

The last thing we decided to made with Python is the hello button, so we attached the led to the GPIO 17 and a push button to the GPIO 2 and creating a new file we wrote this program:

from gpiozero import LED, Button
from time import sleep

led = LED(17)
button = Button(2)

button.wait_for_press()
led.on()
sleep(3)
led.off()

6th Exercise :

With the idea to try the arquitecture with other languages, we decide to use Processing for blinking the LED there:

The other thing we made was used the same arquitecture with different language such as Processing for interface with the raspberry and create any graphics there can also be used for physical computing.

1. First step was to import the GPIO library in processing and declare the main variable for the led, his initial value or state 0 - LOW -false.

2. At the setup we declare the GPIO pin mode as an OUTPUT and where is attached as parameters.

3. Finally at the draw, we made a conditional for trigger the state of the led to the background when we clicked the mouse.

import processing.io.*; // use the GPIO library

// store the desired state of the LED in a variable
boolean ledOn = false;

void setup() {
  // set pin 17 as an output:
  GPIO.pinMode(17, GPIO.OUTPUT);
}

void draw() {
  if (ledOn == true) { // If the desired state is on, then:

  	// turn the LED on:
    GPIO.digitalWrite(17, GPIO.HIGH);

    // and set the background green:
    background(0,255, 0);
  }

  else { // otherwise:

  	// turn the LED off:
    GPIO.digitalWrite(17, GPIO.LOW);

    // and set the background black:
    background(0, 0, 0);
  }
}

void mouseClicked() {
  // When the mouse is clicked, store the opposite of
  // ledOn into ledOn, which toggles ledOn:
  ledOn = !ledOn;
}

7th Exercise :

For finnish, we decide to try another programming language present in Raspbian, is another open and fun tool from the MIT and Pilu use a lot with their childrens at the primary and secondary school : SCRATCH

Lucio Pentagna

INDIVIDUAL WEB PAGE

Pilar Caballero

INDIVIDUAL WEEK PAGE