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Arduino

March 28, 2014 Previous day Next day

Every second and fourth Thursday of each month, I teach a class at my local makerspace, theClubhou.se that centers on STEM Education. Youth between the ages of 8 and 17 attend the class and we strive to teach them how to create fun projects that will hopefully inspire them to embark onto larger projects in the future.

 

During our November and December sessions this past year, we decided that we would teach the YoungMakers how to index strands of LED Christmas lights using nothing but an Arduino, a few Relays, and some LEDs as a proof of concept. After some research, we decided that the best route to take would be to use a program called Vixen Lights to simplify the sequencing process as much as possible. This was necessary because we only had a total of about six-hours spread out over 2 months to complete everything.

 

While I have documented the process we took for the curriculum we wrote around this project, I have yet to take the time to document it online. That is the purpose of this posting and by the end of this post I hope you will be able to use Vixen Lights to sequence some LEDs of your own. Below is a list of materials you will need to complete this tutorial, and almost everything can be bought from Newark.com. You can find all of the necessary code, and related files in my GitHub Repository for this project.

 

 

So to kick this off, we need to plug our LEDs into the breadboard. To simplify things, I like to plug the cathode of each LED into the GND rail of the breadboard, and place the anode into the five-position strip that is in line with the GND hole you plugged the cathode into.  This will allow us to use a jumper wire to connect the anode to the PWM pins on the Arduino, and let us only utilize a single GND port on the Arduino as well.

 

IMG_3306.jpg

 

Make sure to space the LEDs far enough apart to ensure that the ping pong balls will have enough room to fit. To get an idea of how much room you will need, six ping pong balls will take up the entire surface area of a standard breadboard. Once you have all of your LEDs in place, push the ping pong balls onto the 5mm LEDs.

 

IMG_3292.jpg

 

With the LEDs now in position, we can move on to wiring everything up. Starting from the left, attach the first LED anode to digital pin 11 on the Arduino. Follow this up by attaching the next LED’s anode to digital pin 10. The third LED attaches to digital pin 9, with the fourth, fifth and sixth attaching to digital pins 6, 5, and 3 respectively.

 

IMG_3294.jpg

 

Once everything is attached, we can move on to importing and adjusting the code for this project to our specific needs. Head over to my Github repository to download all of the files used in this tutorial, or you can copy and paste the code I have listed below.

 

IMG_3295.jpg

 

Base Code (Needs Modifying)

/*
The purpose of this code is to allow the Arduino to use the
Generic serial output of vixen lights to control 5 channels of LEDs.
Author: Matthew Strange
Created: 14 October 2010

*/

// Output
int Chan1 = 5; // green LED, connected to digital pin 5
int Chan2 = 6; // white LED, connected to digital pin 6
int Chan3 = 9; // red LED, connected to digital pin 9
int Chan4 = 10; // green LED, connected to digital pin 10
int Chan5 = 11; // red LED, connected to digital pin 11

int i = 0; // Loop counter
int incomingByte[8]; // array to store the 7 values from the serial port

//setup the pins/ inputs & outputs
void setup()
{
  Serial.begin(9600); // set up Serial at 9600 bps

  pinMode(Chan1, OUTPUT); // sets the pins as output
  pinMode(Chan2, OUTPUT);
  pinMode(Chan3, OUTPUT);
  pinMode(Chan4, OUTPUT);
  pinMode(Chan5, OUTPUT);
}

void loop()
{ // 7 channels are coming in to the Arduino
  if (Serial.available() >= 5) {
  // read the oldest byte in the serial buffer:
  for (int i=0; i<8; i++) {
  // read each byte
  incomingByte[i] = Serial.read();
  }

  analogWrite(Chan1, incomingByte[0]); // Write current values to LED pins
  analogWrite(Chan2, incomingByte[1]); // Write current values to LED pins
  analogWrite(Chan3, incomingByte[2]); // Write current values to LED pins
  analogWrite(Chan4, incomingByte[3]); // Write current values to LED pins
  analogWrite(Chan5, incomingByte[4]); // Write current values to LED pins
  }
}




 

With the code now open in the Arduino IDE, we need to make some adjustments to it to better match our setup.  The first thing we need to do is adjust the output to follow the schematic on how we hooked up our LEDs on the breadboard. Edit the output to match the code below. What we are doing is telling the Arduino that channel 1 on the breadboard equals pin 11 and so on. This is important because Vixen will tell the Arduino later which channel to turn on during the sequence.

 

Adjust Output Pin Definitions

// Output
int Chan1 = 11; // green LED, connected to digital pin 11
int Chan2 = 10; // white LED, connected to digital pin 10
int Chan3 = 9; // red LED, connected to digital pin 9
int Chan4 = 6; // green LED, connected to digital pin 6
int Chan5 = 5; // red LED, connected to digital pin 5
int Chan6 = 3; // red LED, connected to digital pin 3




 

Up next we need to adjust the set up to match the settings of our output. Again make the code in your sketch match the code below. Basically this tells the Arduino that all six channels defined above should be treated as outputs.

 

Adjust Setup Code

void setup()
{
  Serial.begin(9600); // set up Serial at 9600 bps

  pinMode(Chan1, OUTPUT); // sets the pins as output
  pinMode(Chan2, OUTPUT);
  pinMode(Chan3, OUTPUT);
  pinMode(Chan4, OUTPUT);
  pinMode(Chan5, OUTPUT);
  pinMode(Chan6, OUTPUT);
}





Vixen will utilize the serial communication port to tell our Arduino which channels to turn on and which to turn off and as such, we need to adjust the number of channels that are coming into the Arduino from the serial port.  The original code specifies 5 channels, but since we are doing 6 channels, we need to adjust this to match.  As we did before, make your code match the code I have pasted below.

 

Adjust Loop Code Part 1

void loop()
{ // 6 channels are coming in to the Arduino
  if (Serial.available() >= 6) {
  // read the oldest byte in the serial buffer:
  for (int i=0; i<7; i++) {
  // read each byte
  incomingByte[i] = Serial.read();
  }




 

Now we are almost finished. We now need to add once analogWrite line to the last part of our code. Since the original code was written for 5 channels, we just need to add one more channel to the loop. The correct code is pasted below. Match your code to this.

 

Adjust Loop Code Part 2

  analogWrite(Chan1, incomingByte[0]); // Write current values to LED pins
  analogWrite(Chan2, incomingByte[1]); // Write current values to LED pins
  analogWrite(Chan3, incomingByte[2]); // Write current values to LED pins
  analogWrite(Chan4, incomingByte[3]); // Write current values to LED pins
  analogWrite(Chan5, incomingByte[4]); // Write current values to LED pins
  analogWrite(Chan6, incomingByte[5]); // Write current values to LED pins




 

With that complete, your code should now look like this. If you see any mistakes, please go back and correct them before continuing on with this tutorial.

 

Final Code

/*
The purpose of this code is to allow the Arduino to use the
generic serial output of vixen lights to control 5 channels of LEDs.
Author: Matthew Strange
Created: 14 October 2010
Adapted for 6-PWM-Channels by Charles Gantt on November 14th 2013.

*/

// Output
int Chan1 = 11; // green LED, connected to digital pin 11
int Chan2 = 10; // white LED, connected to digital pin 10
int Chan3 = 9; // red LED, connected to digital pin 9
int Chan4 = 6; // green LED, connected to digital pin 6
int Chan5 = 5; // red LED, connected to digital pin 5
int Chan6 = 3; // red LED, connected to digital pin 3

int i = 0; // Loop counter
int incomingByte[8]; // array to store the 7 values from the serial port

//setup the pins/ inputs & outputs
void setup()
{
  Serial.begin(9600); // set up Serial at 9600 bps

  pinMode(Chan1, OUTPUT); // sets the pins as output
  pinMode(Chan2, OUTPUT);
  pinMode(Chan3, OUTPUT);
  pinMode(Chan4, OUTPUT);
  pinMode(Chan5, OUTPUT);
  pinMode(Chan6, OUTPUT);
}

void loop()
{ // 7 channels are coming in to the Arduino
  if (Serial.available() >= 6) {
  // read the oldest byte in the serial buffer:
  for (int i=0; i<7; i++) {
  // read each byte
  incomingByte[i] = Serial.read();
  }

  analogWrite(Chan1, incomingByte[0]); // Write current values to LED pins
  analogWrite(Chan2, incomingByte[1]); // Write current values to LED pins
  analogWrite(Chan3, incomingByte[2]); // Write current values to LED pins
  analogWrite(Chan4, incomingByte[3]); // Write current values to LED pins
  analogWrite(Chan5, incomingByte[4]); // Write current values to LED pins
  analogWrite(Chan6, incomingByte[5]); // Write current values to LED pins
  }
}




 

1.jpg

Once the code is complete, its time to verify and upload the code to your Arduino. You can do this by simply clicking the “Play” button which is second from the left at the top of the Arduino window. If everything uploads correctly and no errors arose, it is time to move onto installing and configuring Vixen. Head over to VixenLights.com and grab the latest version of Vixen Lights 2.

 

2.jpg

 

Installing Vixen is fairly simple as it comes already unpacked into its directory. Make sure to place it somewhere you will remember to find it such as the desktop, or in your documents folder. To begin, launch Vixen and let’s set up a sequence. This is a very important step and very close attention should be paid and every step should be followed exactly for things to work properly. To start, click on the sequence tab and navigate to New Event Sequence > Vixen Standard Sequence.

 

3.jpg

 

Once you click on Vixen Standard Sequence the New Sequence Wizard will pop up and prompt you with a few configurable options. The first major thing you will need to set up is the Event Period. This value determines the period of time that each LED will stay lit. You can adjust this time down to 25-miliseconds and up as high as 1 second. For the purpose of this tutorial, we are going to keep it simple at 100-miliseconds, giving us 10 events per channel, per second.

 

4.jpg

 

Up next is where most of the configuration happens. To make things simple, we are going to create a profile that we can save and re-use in the future.  Click Profile Manager and then click the Add icon that is highlighted in the image above.

 

5.jpg

 

Give the new profile a name and then click OK. At this point the Edit Profile screen will pop up, and you need to add six channels.

 

6.jpg

 

Once the six channels have been added click the Output Plugins button and you will see the Sequence Plugin Mapping configuration window pop up. Under Available Plugins, select Generic Serial, and click the Use button. Set the channels from 1 to 6, and click the Plugin Setup button.

 

7.jpg

 

Set the Com Port to 4 (also make sure your Arduino is set to Com Port 4) and set the Baud Rate to 9600 and then click OK.

 

8.jpg

 

The Profile window will once again pop up, and you will need to select the profile you just created, and then click next. Since we are not adding any audio to this sequence, click next on the Audio and Event Patterns window.

 

9.jpg

 

Finally we are presented with the Sequence Time configuration window. For this tutorial I have set it to 1-minute, but you can set this to any length you desire. Once you have your time set, click the Create It button and you will be prompted to save this sequence. Give it a name, and click Save.

 

16.jpg

 

The PC will take a few moments to process and create your sequence, but when finished, a sequence configuration window will open and the sequence will be represented in a timeline that is sectioned into a grid-like pattern. Each one of these little blocks represents a single event period, and can be used to turn that channel on, off, or set a brightness value.

 

17.jpg

 

To keep things organized and easy to configure we need to assign a color to each channel. To do this we must right click on the channel list, and select Channel Properties.

 

18.jpg19.jpg

 

When you click Channel Properties, a small window will pop up and will have several configurable options. For the purpose of this tutorial, we will just be changing each channels color. Set the first one to red, and then click the channel dropdown and select channel two.

20.jpg


Continue doing this until each channel has a unique color. I color coded the channels in my sequence to reflect the LED colors on my breadboard.

 

21.jpg

 

So let’s begin building the sequence. Click and highlight the event periods you wish to enable, and then click the solid square button in the control bar as seen highlighted in the image above. You can also enable the event periods by pressing the spacebar. Play around with the rest of the buttons on that row for some cool effects. I don’t want to dive too deep into building advanced sequences as that is an entire article on its own, and this tutorial is already long enough.

 

 

Now we can run the sequence. Make sure the Arduino is plugged in and is set to Com Port 4 in the Device Manager. If everything is correct, click the play button located at the top left of the Vixen Sequence. You should see the LEDs begin to light up and follow the sequence you just built. If you get a router / com port error, simply save your sequence, close Vixen and Arduino and reopen Vixen and load your sequence. Things should work now.

 

You can adapt this same setup to trigger relays to control 110v circuits that can activate LED Christmas Lights, Halloween Lighting, or pretty much anything that runs on mains voltage. Below is a video of a 4-christmas tree setup I built with my Makerspace that sequenced 32 channels of LED Christmas Lights.

 

 

Next Guides:

Getting to Know Arduino : Part 2 : Hello, Again!

Getting to Know Arduino : Part 3 : Taking your Temperature

 

I recorded a video to introduce the Arduino UnoArduino Uno and how to get started with it. The premise was that you didn't need to add anything extra, except for an A to B USB cableA to B USB cable (always check the type you need for the Arduino you have) because although you can connect an external power supply it can be powered purely from the USB, and you could get code running with a few simple steps on Microsoft Windows to make an LED (Light Emitting Diode) start to flash on your board.

arduino_uno_components.jpg

The Arduino I showed in the video was a revision 3 board, there have been a few versions so far, in the image (from zenbike.co.uk) you can see an earlier version, but it nicely maps out the connectors on the board. I think in the recent version the reset button has moved, but that makes little difference overall. What it doesn't note on the image is that any socket with the ~ (tilde) symbol next to it can be used as a Pulse Width Modulation output. This is a way of having a digital signal pretend that it's analogue but typically you don't need to worry about this until you've got some hardware that you need to output to which needs it.

 

The first instruction we can make the Arduino perform is to flash an LED, which is often considered the "Hello, World!" of getting started. The example code 'Blink' will do this for you, it flashes the LED marked 'L' on the board. This LED is also linked up with the breakout pin '13' like many connections on the board, some go through components and others do not, but they ultimately connect to the ATMega328 micro-controller processor on the board, which is the brains of it all.

 

We'll need to tell the Arduino what we want it to do and for that we can use the Arduino Integrated Development Environment (IDE), this environment contains a text editor and a console window which shows you any error messages and how successful the software has been when communicating with the Arduino. You can get the IDE for more than just Microsoft Windows, there are Mac OS and Linux variants. You might want to check your package manager and software repository for whether or not there is a version pre-packaged for your version of Linux. For example you can use apt-get on Ubuntu to "apt-get install arduino" from a terminal.

 

It's often best to get the latest non-beta version of the Arduino IDE, but if you have a board that is newer then usually this isn't supported in the 'stable' builds and a beta or nightly build is required.

 

After installing the Arduino IDE in Microsoft Windows, you'll need to connect your Arduino Uno if you haven't already. It may help to reconnect it so that it re-detects the device and installs the driver. Then you can run the IDE. To be able to upload code to the device you will need to know what COM port it is running on.

 

To do this, open your Start menu, navigate to Control Panel, once the window appears, open System and then navigate around the tabs/options until you find Device Manager. With this window open, click the + symbol next to "Ports (COM & LPT)" and the Arduino should be listed along with its COM and a number.

 

In the IDE, go to the Tools menu and then expand Board and choose your Arduino, then do the same, but go to Serial Port and choose the one that it stated in Device Manager.

 

Now to get the LED flashing, choose the File menu, go to Examples and then 01.Basics, under this menu navigate to Blink. To get this running on your Arduino you can now either click on the arrow next to the tick icon or choose the Sketch menu and click Verify/Compile. Now the 'L' LED on your board should be blinking!

 

Feel free to change the code, copy and paste bits to see what works and what doesn't.

 

This will open a new window with the following code in it:

 

/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.

  This example code is in the public domain.
*/

// Pin 13 has an LED connected on most Arduino boards.
// give it a name:
int led = 13;

// the setup routine runs once when you press reset:
void setup() {        
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}
        

 

This is what is referred to as a 'sketch' in IDE terms, however it is actually using a low level programming language called C++ which has been around for a notable amount of time, most of the software you use is written with C++ including Microsoft Windows and parts of Linux.

 

Line 01 and 06 in the code uses text that the IDE recognises as a special arrangement so that it knows to ignore anything typed between them (it denotes that whatever is between them is a comment. On line 08 it shows the line starting with a similar arrangement that means to ignore that entire line as a comment.

 

int led = 13;
        

 

This line is literally mathematical, it could be said that programming is inherently mathematical because processors are just doing calculations and moving numbers around. So this line in particular is declaring that the english word, led is a certain type of variable (kinda like a bucket that can only contain something of a particular thing and its contents can vary) and that is called an integer, which means a whole number. As opposed to a number with a decimal (or a real number). We're then making the contents of the variable (or bucket) equal to the number 13. What then terminates the line is a semicolon and this is required by the IDE to know that we're finished putting commands on the line.

 

The IDE, or specifically the part of it that changes our near-english (sketch/programming) into a language that the Arduino can understand typically operates on a line by line basis, which is like how old typewriters used to work where by you normally couldn't go back and change what you had just created/read and had to continue (probably a bad analogy).

 

void setup() { }
       

 

The setup declaration is called a function, anything within { } is processed by the IDE, 'setup' is a reserved name for the function and it means that it is ran before anything else within the sketch. Like the variable led is of a type int, the setup function is of a type void. We don't have to worry about that for now. pinMode() is another function that is referred to and you can read up about it.

 

void loop() { }
       

 

The loop function is another reserved name that means anything within { } is ran again from the first { when it reaches the last line or instruction before the final }. The speed of this is governed by how fast the microprocessor, for example the ATMega328 can get through the instructions per second. The digitalWrite() and delay() functions can also be read up about on the Reference section of the Arduino site.

 

Hopefully you have found this useful to get started with your Arduino and it has introduced you to some new concepts for programming for micro-controllers. The best way to learn is trial and error, so don't be afraid to mess around with the code or read up about it.

 

If you have any questions, problems or otherwise please leave a comment! You can also find more information in Arduino community group!

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