Posts with «color» label

Color-Coded Key Opens Doors, Opportunities

Of all the ways to open up a lock, there are some tried and true methods. Keys, combinations, RFIDs, picks, and explosives have all had their time and place, but now someone else wants to try something new. [Erik] has come up with a lock that opens when it is shown a pattern of colors.

The lock in question uses a set of color coded cards as the “keys”. When the cards are inserted in the lock, a TCS230 color sensor interprets the pattern on the cards and sends the information over to an Arduino Uno. From there, the Arduino can command the physical lock to open if the pattern is a match, although [Erik] is still waiting on the locking mechanism to arrive while he continues to prototype the device.

This is a fairly unique idea with a number of upsides. First, the code can’t be “stolen” from inside a wallet like RFID cards can. (Although if you can take a picture of the card all bets are off.) If you lose your key, you can simply print another one, and the device is able to handle multiple different keys and log the usage of each one. Additionally, no specialized equipment is needed to create the cards, unlike technologies that rely on magnetic strips. Of course, there’s always this classic way of opening doors if you’d rather go old school with your home locks.

Hack a Day 10 Mar 00:00

Tutorial – Arduino and Color LCD

Learn how to use an inexpensive colour LCD shield with your Arduino. This is chapter twenty-eight of our huge Arduino tutorial series.

Updated 03/02/2014

There are many colour LCDs on the market that can be used with an Arduino, and for this tutorial we’re using a relatively simple model available that is available from suppliers such as Tronixlabs, based on a small LCD originally used in Nokia 6100 mobile phones:

These are a convenient and inexpensive way of displaying data, or for monitoring variables when debugging a sketch. Before getting started, a small amount of work is required.

From the two examples we have seen, neither of them arrive fitted with stacking headers (or in Sparkfun’s case – not included) or pins, so before doing anything you’ll need to fit your choice of connector. Although the LCD shield arrived with stacking headers, we used in-line pins as another shield would never be placed on top:

Which can easily be soldered to the shield in a few minutes:

 While we’re on the subject of pins – this shield uses D3~D5 for the three buttons, and D8, 9, 11 and 13 for the LCD interface. The shield takes 5V and doesn’t require any external power for the backlight. The LCD module has a resolution of 128 x 128 pixels, with nine defined colours (red, green, blue, cyan, magenta, yellow, brown, orange, pink) as well as black and white.

So let’s get started. From a software perspective, the first thing to do is download and install the library for the LCD shield. Visit the library page here. Then download the .zip file, extract and copy the resulting folder into your ..\arduino-1.0.x\libraries folder. Be sure to rename the folder to “ColorLCDShield“. Then restart the Arduino IDE if it was already open.

At this point let’s check the shield is working before moving forward. Once fitted to your Arduino, upload the ChronoLCD_Color sketch that’s included with the library, from the IDE Examples menu:

This will result with a neat analogue clock you can adjust with the buttons on the shield, as shown in this video.

It’s difficult to photograph the LCD – (some of them have very bright backlights), so the image may not be a true reflection of reality. Nevertheless this shield is easy to use and we will prove this in the following examples. So how do you control the color LCD shield in your sketches?

At the start of every sketch, you will need the following lines:

#include "ColorLCDShield.h"
LCDShield lcd;

as well as the following in void setup():

lcd.init(PHILIPS); 
lcd.contrast(63); // sets LCD contrast (value between 0~63)

With regards to lcd.init(), try it first without a parameter. If the screen doesn’t work, try EPSON instead. There are two versions of the LCD shield floating about each with a different controller chip. The contrast parameter is subjective, however 63 looks good – but test for yourself.

Now let’s move on to examine each function with a small example, then use the LCD shield in more complex applications.

The LCD can display 8 rows of 16 characters of text. The function to display text is:

lcd.setStr("text", y,x, foreground colour, background colour);

where x and y are the coordinates of the top left pixel of the first character in the string. Another necessary function is:

lcd.clear(colour);

Which clears the screen and sets the background colour to the parameter colour.  Please note – when referring to the X- and Y-axis in this article, they are relative to the LCD in the position shown below. Now for an example – to recreate the following display:

… use the following sketch:

// Example 28.1
#include "ColorLCDShield.h"
LCDShield lcd;

void setup()
{
 // following two required for LCD
 lcd.init(PHILIPS); 
 lcd.contrast(63); // sets LCD contrast (value between 0~63)
}

void loop()
{
 lcd.clear(BLACK);
 lcd.setStr("ABCDefghiJKLMNOP", 0,2, WHITE, BLACK);
 lcd.setStr("0123456789012345", 15,2, WHITE, BLACK);
 lcd.setStr("ABCDefghiJKLMNOP", 30,2, WHITE, BLACK);
 lcd.setStr("0123456789012345", 45,2, WHITE, BLACK);
 lcd.setStr("ABCDefghiJKLMNOP", 60,2, WHITE, BLACK);
 lcd.setStr("0123456789012345", 75,2, WHITE, BLACK);
 lcd.setStr("ABCDefghiJKLMNOP", 90,2, WHITE, BLACK);
 lcd.setStr("0123456789012345", 105,2, WHITE, BLACK);
 do {} while (1>0);
}

In example 28.1 we used the function lcd.clear(), which unsurprisingly cleared the screen and set the background a certain colour.

Let’s have a look at the various background colours in the following example. The lcd.clear()  function is helpful as it can set the entire screen area to a particular colour. As mentioned earlier, there are the predefined colours red, green, blue, cyan, magenta, yellow, brown, orange, pink, as well as black and white. Here they are in the following example:

// Example 28.2

int del = 1000;
#include "ColorLCDShield.h"
LCDShield lcd; 
void setup() 
{ 
  // following two required for LCD 
  lcd.init(PHILIPS); 
  lcd.contrast(63); // sets LCD contrast (value between 0~63) 
}

void loop()
{
 lcd.clear(WHITE);
 lcd.setStr("White", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(BLACK);
 lcd.setStr("Black", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(YELLOW);
 lcd.setStr("Yellow", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(PINK);
 lcd.setStr("Pink", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(MAGENTA);
 lcd.setStr("Magenta", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(CYAN);
 lcd.setStr("Cyan", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(BROWN);
 lcd.setStr("Brown", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(ORANGE);
 lcd.setStr("Orange", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(BLUE);
 lcd.setStr("Blue", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(RED);
 lcd.setStr("Red", 39,40, WHITE, BLACK);
 delay(del);
 lcd.clear(GREEN);
 lcd.setStr("Green", 39,40, WHITE, BLACK);
 delay(del);
}

And now to see it in action. In this demonstration video the colours are more livid in real life, unfortunately the camera does not capture them so well.

 

Now that we have had some experience with the LCD library’s functions, we can move on to drawing some graphical objects. Recall that the screen has a resolution of 128 by 128 pixels. We have four functions to make use of this LCD real estate, so let’s see how they work. The first is:

lcd.setPixel(int colour, Y, X);

This function places a pixel (one LCD dot) at location x, y with the colour of colour.

Note – in this (and all the functions that have a colour parameter) you can substitute the colour (e.g. BLACK) for a 12-bit RGB value representing the colour required. Next is:

lcd.setLine(x0, y0, x1, y1, COLOUR);

Which draws a line of colour COLOUR, from position x0, y0 to x1, y1. Our next function is:

lcd.setRect(x0, y0, x1, y1, fill, COLOUR);

This function draws an oblong or square of colour COLOUR with the top-left point at x0, y0 and the bottom right at x1, y1. Fill is set to 0 for an outline, and 1 for a filled oblong. It would be convenient for drawing bar graphs for data representation. And finally, we can also create circles, using:

lcd.setCircle(x, y, radius, COLOUR);

X and Y is the location for the centre of the circle, radius and COLOUR are self-explanatory. We will now use these graphical functions in the following demonstration sketch:
// Example 28.3

#include "ColorLCDShield.h"
LCDShield lcd;
int del = 1000;
int xx, yy = 0;

void setup()
{
  lcd.init(PHILIPS); 
  lcd.contrast(63); // sets LCD contrast (value between 0~63)
  lcd.clear(BLACK);
  randomSeed(analogRead(0));
}

void loop()
{
  lcd.setStr("Graphic Function", 40,3, WHITE, BLACK);
  lcd.setStr("Test Sketch", 55, 20, WHITE, BLACK); 
  delay(5000);
  lcd.clear(BLACK);
  lcd.setStr("lcd.setPixel", 40,20, WHITE, BLACK);
  delay(del);
  lcd.clear(BLACK);
  for (int a=0; a<500; a++)
  {
    xx=random(160);
    yy=random(160);
    lcd.setPixel(WHITE, yy, xx);
    delay(10);
  }
  delay(del);
  lcd.clear(BLACK);
  lcd.setStr("LCDDrawCircle", 40,10, WHITE, BLACK);
  delay(del);
  lcd.clear(BLACK); 
  for (int a=0; a<2; a++)
  {
    for (int b=1; b<6; b++)
    {
      xx=b*5;
      lcd.setCircle(32, 32, xx, WHITE);
      delay(200);
      lcd.setCircle(32, 32, xx, BLACK);
      delay(200);
    }
  }
  lcd.clear(BLACK); 
  for (int a=0; a<3; a++)
  {
    for (int b=1; b<12; b++)
    {
      xx=b*5;
      lcd.setCircle(32, 32, xx, WHITE);
      delay(100);
    }
    lcd.clear(BLACK);
  }
  lcd.clear(BLACK); 
  for (int a=0; a<3; a++)
  {
    for (int b=1; b<12; b++)
    {
      xx=b*5;
      lcd.setCircle(32, 32, xx, WHITE);
      delay(100);
    }
    lcd.clear(BLACK);
  }
  delay(del);
  lcd.clear(BLACK);
  lcd.setStr("LCDSetLine", 40,10, WHITE, BLACK);
  delay(del);
  lcd.clear(BLACK); 
  for (int a=0; a<160; a++)
  {
    xx=random(160);
    lcd.setLine(a, 1, xx, a, WHITE);
    delay(10);
  }
  lcd.clear(BLACK);
  lcd.setStr("LCDSetRect", 40,10, WHITE, BLACK);
  delay(del);
  lcd.clear(BLACK); 
  for (int a=0; a<10; a++)
  {
    lcd.setRect(32,32,64,64,0,WHITE);
    delay(200);
    lcd.clear(BLACK);
    lcd.setRect(32,32,64,64,1,WHITE);
    delay(200);
    lcd.clear(BLACK); 
  }
  lcd.clear(BLACK); 
}

The results of this sketch are shown in this video. For photographic reasons, I will stick with white on black for the colours.

So now you have an explanation of the functions to drive the screen – and only your imagination is holding you back.

Conclusion

Hopefully this tutorial is of use to you. and you’re no longer wondering “how to use a color LCD with Arduino”. They’re available from our tronixlabs store. And if you enjoyed this article, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop”.

Have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column, or join our forum – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

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Review – Freetronics 128×128 Pixel Colour OLED Module

Introduction

Time for another review, and in this instalment we have the new 128×128 Pixel OLED Module from Freetronics. It’s been a while since we’ve had a full-colour graphic display to experiment with, and this one doesn’t disappoint. Unlike other displays such as LCD, this one uses OLED – “Organic Light-Emitting Diode” technology.

OLEDs allow for a faster refresh rate, and to the naked eye has a great amount of colour contrast. Furthermore the viewing angles are excellent, you can clearly read the display from almost any angle, for example:

However they can suffer from burn-in from extended display of the same thing so that does need to be taken into account. Nevertheless they provide an inexpensive and easy-to-use method of displaying colour text, graphics and even video from a variety of development boards. Finally – there is also a microSD socket for data logging, image storage or other uses. However back to the review unit. It arrives in typical retail packaging:

and includes the OLED display itself, a nifty reusable parts tray/storage box, and two buttons. The display has a resolution of 128 x 128 pixels and has a square display area with a diagonal size of 38.1 mm. The unit itself is quite compact:

The display is easily mounted using the holes on the left and right-hand side of the display. The designers have also allowed space for an LED, current-limiting resistor and button on each side, for user input or gaming – perfect for the  included buttons. However this section of the PCB is also scored-off so you can remove them if required. Using the OLED isn’t difficult, and tutorials have been provided for both Arduino and Raspberry Pi users.

Using with Arduino

After installing the Arduino library, it’s a simple matter of running some jumper wires from the Arduino or compatible board to the display – explained in detail with the “Quickstart” guide. Normally I would would explain how to use the display myself, however in this instance a full guide has been published which explains how to display text of various colours, graphics, displaying images stored on a microSD card and more. Finally there’s some interesting demonstration sketches included with the library. For example, displaying large amounts of text:

… the variety of fonts available:

… and for those interested in monitoring changing data types, a very neat ECG-style of sketch:

… and the mandatory rotating cube from a Freetronics forum member:

Using with Raspberry Pi

For users of this popular single-board computer, there’s a great tutorial and some example videos available on the Freetronics website for your consideration, such as the following video clip playback:

Support

Along with the Arduino and Raspberry Pi tutorials, there’s also the Freetronics support forum where members have been experimenting with accelerated drivers, demonstrations and more.

Competition!

For a chance to win your own OLED display, send a postcard with your email address clearly printed on the back to:

OLED Competition, PO Box 5435 Clayton 3168 Australia. 

Cards must be received by 24/10/2013. One card will then be selected at random and the winner will be sent one Freetronics OLED Display. Prize will be delivered by Australia Post standard air mail. We’re not responsible for customs or import duties, VAT, GST, import duty, postage delays, non-delivery or whatever walls your country puts up against receiving inbound mail.

Conclusion

Compared to previous colour LCD units used in the past, OLED technology is a great improvement – and demonstrated very well with this unit. Furthermore you get the whole package – anyone call sell you a display, however Freetronics also have the support, tutorials, drivers and backup missing from other retailers. So if you need a colour display, check it out.

And for more detail, full-sized images from this article can be found on flickr. And if you’re interested in learning more about Arduino, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a third printing!) “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

[Note – OLED display was a promotional consideration from Freetronics]

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