Lesson 1 – Blinking LED
Booting up the Raspberry Pi
- This section assumes that you have read through “Lesson 0 – Setup” and have a working Raspberry Pi you can connect to remotely using SSH or VNC.
- If that’s not the case please head back to “Lesson 0 – Setup” and work through the instructions provided.
- Let’s now get started and boot up the Raspberry Pi.
- Grab a good quality USB cable and a USB power adaptor (2.5A).
- Plug one end of the USB cable into the plug and the other microUSB end into the Raspberry Pi.
- This should now power up the Raspberry Pi.
- Once the Raspberry Pi has booted up, please ensure that it is able to connect it to the network so that you can access it over VNC.
- If you are using a local monitor connected to the Raspberry Pi, you are all sorted.
- Else get connected to the Raspberry Pi using VNC.
Important links –
Here’s some important links. Have a read when you get a chance –
- Review the list of components that come along with the Sunfounder Super Startup Kit for the Raspberry Pi 3 – <Link>
- Read through a short description of the various components that come along with the Sunfounder Super Startup Kit for the Raspberry Pi 3 – <Link>
- Read through the Sunfounder documentation to make sure you have setup your development environment on the Raspberry Pi – <Link>
Important Concepts – We have put together a document to cover the basics of –
- What is a breadboard
- What are resistors
- What are LED’s
Let’s get started – Our next tutorial is called, “Blinking LED”. As part of this tutorial we will build our first circuit using a breadboard.
We will wire up an LED, connect it up to the Raspberry Pi through a 220 Ohm resistor, power it up and write some python code.
We will then use a resistor to limit the current flowing through the LED. In this lesson, we will learn how to program Raspberry Pi to make an LED blink. Once you have learned how to trigger an LED on and off you can use similar logic to build circuits with LED’s of different colors and turn them on/off creating lighting patterns. Now, let’s get started.
Components required for this tutorial include –
- 1 Raspberry Pi
- 1 Breadboard
- 1 Raspberry Pi Cobbler / T-Extension Board
- 1 40-Pin Cable to connect the Raspberry Pi Cobbler / T-Extension Board to the Raspberry Pi
- 1 LED
- 1 Resistor (220Ω)
- Dupont jumper wires
Let’s get started and wire up your circuit based on the fritzing diagram below.
PLEASE NOTE – Please make sure you have disconnected your breadboard from the Raspberry Pi before commencing build of the circuit. Once you have put the circuit together, get someone around you to review the circuit and confirm that the connections are proper before you proceed and power up the breadboard.
Wiring Up – In this experiment, we have connected a 220Ω resistor to the anode (the longer leg of the LED is the Anode and the shorter leg of the LED is the Cathode), followed by the other end of the resistor to our 3.3 V power source on the breadboard (using the Raspberry Pi Cobbler / T-Extension Board) and finally connected the connect the cathode (the shorter leg) of the LED to B17 of Raspberry Pi. The fritzing diagram below provides a view of all of the connections that need to be made for this tutorial.
To summarize our connections look like the following –
- Setup the Raspberry Pi Cobbler / T-Extension Board on the Breadboard.
- See the fritzing diagram below to understand what a suitable setup might look like.
- Note that one pair of the Ground/3.3V connects to the upper two (horizontally connected) rows of the breadboard.
- The second pair of the Ground/5V connects to the lower two (horizontally connected) rows of the breadboard.
- Wire up the 220Ω resistor to the anode (the longer leg of the LED is the Anode and the shorter leg of the LED is the Cathode)
- Wire up the other end of the resistor to our 3.3 V power source on the breadboard (using the Raspberry Pi Cobbler / T-Extension Board)
- Wire up the cathode (the shorter leg) of the LED to B17 of Raspberry Pi.
How Does It Work –
We can see from the schematic diagram below that the Anode of the LED connects to a 220 Ohm current-limiting resistor and then to 3.3V power source (on the Raspberry Pi using the Raspberry Pi Cobbler / T-Extension Board). Therefore, to turn on an LED, we need to program the B17 pin on the Raspberry Pi to be low (0 Volt). This can be achieved using a few different programming languages but in our case we will be using Python.
Here’s what the real world project will look like once you have wired up all the relevant components i.e. Raspberry Pi 3B+, Raspberry Pi Cobbler / T-Extension Board, breadboard, 220 Ohm resistor and an LED.
Let’s Write Some Python Code – Open up your favorite code editor on your Raspberry Pi and let’s start putting together some code……
#!/usr/bin/env python import RPi.GPIO as GPIO import time # Set #17 as LED pin LedPin = 17 # Define a function to print message at the beginning def print_message(): print ("========================================") print ("| Blink LED |") print ("| ------------------------------ |") print ("| LED connect to GPIO0 |") print ("| |") print ("| LED will Blink at 500ms |") print ("| |") print ("| SunFounder|") print ("========================================\n") print 'Program is running...' print 'Please press Ctrl+C to end the program...' raw_input ("Press Enter to begin\n") # Define a setup function for some setup def setup(): # Set the GPIO modes to BCM Numbering GPIO.setmode(GPIO.BCM) # Set LedPin's mode to output, # and initial level to High(3.3v) GPIO.setup(LedPin, GPIO.OUT, initial=GPIO.HIGH) # Define a main function for main process def main(): # Print messages print_message() while True: print '...LED ON' # Turn on LED GPIO.output(LedPin, GPIO.LOW) time.sleep(0.5) print 'LED OFF...' # Turn off LED GPIO.output(LedPin, GPIO.HIGH) time.sleep(0.5) # Define a destroy function for clean up everything after # the script finished def destroy(): # Turn off LED GPIO.output(LedPin, GPIO.HIGH) # Release resource GPIO.cleanup() # If run this script directly, do: if __name__ == '__main__': setup() try: main() # When 'Ctrl+C' is pressed, the child program # destroy() will be executed. except KeyboardInterrupt: destroy()
See a PDF copy of this tutorial here – <Link>
About the Raspberry Pi
The Raspberry Pi is a series of small single-board computers developed in the United Kingdom by the Raspberry Pi Foundation to promote the teaching of basic computer science in schools and in developing countries. It is a capable little computer which can be used in electronics projects, and for many of the things that your desktop PC does, like spreadsheets, word processing, browsing the internet, and playing games. The original model became far more popular than anticipated, selling outside its target market for uses such as robotics.
The Raspberry Pi does not include peripherals (such as keyboards, mice and cases). However, some accessories have been included in several official and unofficial bundles. According to the Raspberry Pi Foundation, over 5 million Raspberry Pis were sold by February 2015, making it the best-selling British computer. By November 2016 they had sold 11 million units, and 12.5m by March 2017, making it the third best-selling “general purpose computer”. In July 2017, sales reached nearly 15 million.In March 2018, sales reached 19 million. Most Pis are made in a Sony factory in Pencoed, Wales; some are made in China or Japan.
You can read more about the Raspberry Pi here – RaspberryPi.org.
- This development track is based on the Rasbperry Pi and the SunFounder Super Starter Kit v3.0 for the Raspberry Pi.
- You will need access to both the Raspberry Pi 3 B and the electronics components part of the SunFounder Super Starter Kit v3.0 for the Raspberry Pi kit to be able to work on these tutorials.
- If you haven’t purchased the Raspberry Pi 3 B yet please head over to our store and purchase one now. You can pick up the SunFounder Super Starter Kit v3.0 for the Raspberry Pi from SunFounder’s website.
- Depending on where you live you might also be able to pick up the Raspberry Pi and SunFounder Super Starter Kit v3.0 for the Raspberry Pi at your local electronics hobby store.
- You can read more about the Raspberry Pi here – RaspberryPi.org.