Programming LED circuit with Arduino IDE

Description

In this lesson students will be using components of the LilyPad development kit to create a circuit of LED’s that are controlled using a basic Arduino program, written in the Arduino IDE. Starting with a simple sequence of turning a LED on and off, the students can be challenged to choose a piece of music with a steady beat and program the lights to turn on and off in time to the music.

During the testing phase, the LilyPad components will be connected using alligator clips before progressing to hand stitching them together using conductive thread for a final product.

Resources

• Lilypad ProtoSnap kit with rechargeable battery
• LilyPad LED’s
• Conductive thread
• Alligator clips
• Arduino IDE installed onto computers
• Mini USB cable
• Chalk or pen for marking fabric
• Felt/Material
• Scissors
• Paper
• Needle
• Pencils for design sketches
• Embroidery hoop (suggested)
• Mac or PC with latest Arduino IDE installed:
  For Windows
  For Mac

Prior Student Learning

An understanding of basic circuitry is essential for this activity as it is important that the threads do not cross over or touch as you may short circuit the board.

Simple hand stitching skills would be beneficial but not essential as the components can be connected with alligator clips.

1. Watch Youtube clip Frozen Christmas Lights (Let It Go)
2. Introduce the LilyPad kit, explaining the components - demonstrate a simple sequence by connecting the battery. Place alligator clip to the + on the microcontroller board and the + on LED. Connect second alligator clip to - on the board and LED. Turn switch to on to see the LED light up.
3. Discuss port connections using alligator clips, and then conductive thread, highlighting the importance of ensuring the wires do not touch.
4. Introducing the MicroController + Arduino provides a detailed description of the LilyPad components.
5. Introduce the concept of functions and discuss how arduino has pre-defined functions for all the LilyPad components. Some of these functions include:
   • loop - for repetition
   • delay - delays action
   • pinMode - for configuring the specified pin to behave either as an input or an output
   • digitalWrite - for writing a low or high value to a pin

• Review basic electronics & circuitry.
• Explore Arduino IDE software that has been installed onto computers & configure port plus select Lilypad in Board Manager
• Upload basic LED blink program to Lilypad
• Connect LED to Lilypad port 5 and type code into Arduino to turn light on an off
• Create diagram flow chart to show connections needed for between 3-5 LEDs
• Students identify the ways in which their planned outcome can be decomposed into functions
• Students identify the key arduino functions and learn how to change parameters and use these these functions to achieve planned outcomes
• Create algorithm to sequence LED’s to turn on and off in a pattern of student’s choosing.
• Select appropriate piece of music and program LED’s to flash in a pattern that is reflective of the beat.
• Hand stitch Lilypad components onto fabric following the flow chart
• Present final project to the class.

The teacher should have an understanding o

• circuitry,
• basic hand sewing techniques
• the elements of C language used in the Arduino IDE
• see Sew Electronics tutorial for programming your lilypad

• Students review knowledge of basic electronics and the issue of short circuits.
• Discuss concept of wearable technology. What is it? Why would it be useful?
• Introduce conductive thread discussing issues with insulation & resistance. The kit contains 2 ply thread that will compromise the brightness of the LED if sewn over a long distance. (This should not be a problem with this task)
• Open Arduino IDE and connect board to computer using mini USB cable
• Select the board type and port ­ Tools_Board Manager_ LilyPad Arduino. Then Tools_port (select the serial port that is corresponds to the USB port eg:COM3
• Open example program in Arduino IDE ­ File_Examples_01Basics_Blink. This program will turn the inbuilt LED on and off at one second (1000) intervals.
• Students can adapt the speed of the flashing by increasing the number eg 3000

  

• Connect one LED to port 5 using the alligator clips from LilyPad port 5 to the + on the LED. Attach a second alligator clip to the Ground
• Type the following into the Arduino IDE:

  #define LED1 5	                //naming pin 5 as LED 1
  
  void setup() {
  
  	// put your setup code here, to run  once:
  
  pinMode(LED1, OUTPUT);	        //initialise the digital pin as an  output
  
  }
  
  void loop() {
  
  	// put your main code here, to run repeatedly: 
  
  digitalWrite(LED1,HIGH);	 //turn the LED on
  
  delay (1000);	                 //wait 1 second and do nothing digitalWrite
  
  (LED1, LOW);	                 //turn LED off
  
  delay (1000);	                 //wait another second and do  nothing
  
  

• Upload the code to the Lilypad - Sketch_Upload
• Students write the pseudocode of this algorithm, focusing on how to decompose their algorithm into the key functions such as initializing the pins/board, writing a value to a pin and delaying.
• Identify the key blocks of the code, in particular the setup() and loop() functions, and discuss their purpose. What about the delay() function? What other functions of interest can students find?
• Introduce the notion of additional functions: for example, the code in the loop() can be a function in itself:

  #define LED1 5	                //naming pin 5 as LED 1
  
  void setup() {
  
  	// put your setup code here, to run  once:
  
  pinMode(LED1, OUTPUT);	        //initialise the digital pin as an  output
  
  }
  
  void lightLed(){
  
  digitalWrite(LED1,HIGH);	//turn the LED on
  
  delay (1000);	                //wait 1 second and do nothing
  
  digitalWrite(LED1, LOW);	//turn LED off
  
  }
  
  void loop() {
  
         // put your main code here, to run  repeatedly:
  
  lightLed();
  
  delay (1000);	               //wait another second and do  nothing
  
  

• Write the pseudocode of the desired algorithm, decomposing the outcome into key arduino functions and functions of their own.
• In groups, students test and debug their programs.
• As each additional LED is connected to the microcontroller - define each and add additional lines of code changing the name to LED2 LED3 etc.
• Choose music and students vary the delay and sequence of LED’s turning on and off to blink to the beat:

  delay (500)                      //wait of half  a second
  
  ** the shortest delay you can use is  1 as decimal numbers won't  work.
  

• Hand stitch all components to fabric following the flow chart.

• Students present their LED Music display to the class together with their sketch diagram.

• Students reflect on their original diagram sketch and indicate any changes made between that and the final design.
• Is their design scalable? What are the limitations to the project? Eg. only 5 LED’s in the kit.
• Where might they market their final project if it was to be advertised and sold? Who would it appeal too?
• What challenges did they face? Eg: difficulty coding or sewing with the conductive thread. What changes could they make to their design or project to address these issues?
• Were they able to easily change existing code to produce a different outcome? What are the advantages/disadvantages of using functions in code?
• Did they discover an interesting/useful function they want to share?

• Download entire lesson plan: PDF version.
• Download entire lesson plan: Microsoft Word version.
• Instructables: Let's Make with Lilypad - Website with additional ideas and instructions.
• Instructables: Wearable Electronics Class - Free online course teaching techniques to build wearable elecontronics and program interactions using Ardunio software. There are variances in the Lilypad kit supplied by CSER and those referred to in the lessons.