Tag Archive | "graphic"

Review – adafruit industries Mini 8×8 LED Matrix with I2C backpack

Introduction

In this review we have a look at the mini 8×8 LED matrix with I2C backpack from adafruit industries. It looked like a small yet versatile display unit for a couple of project ideas, so as part of the evaluation we’ll run through it with you here. As you can see below, it’s quite small with a 20mm square matrix:

contents

The matrix and the controller are seperate which gives you the option of ordering different colours of matrix. Using LED matrices can be a pain, however these units use the Holtek 16K33 controller IC (data sheet) which has an I2C interface – much easier than the usual mess of shift registers and I/O pins:

holtek

 Furthermore you can change the I2C address using the solder pads on the PCB, giving you four possible options. And as it’s I2C, you can use it with other microcontrollers with a little detective work. Moving forward, we’ll assemble the display then explain how to use it with an Arduino, and show a few demonstrations.

Assembly

There really isn’t anything major to do, just solder the matrix to the backpack and some header pins if you need them. adafruit include some however I’m using the 90-degree ones for my own use:

solderingpins

The soldering should take about one minute tops, and then you’re done:

finished

Using the matrix

From a hardware perspective you only have four wires – 5V, GND, SDA and SCL. Yes – it’s a 5V part, so all you Raspberry Pi fans will need a level shifter, which you can get from adafruit as well. Anyhow once you’ve got it connected to your Arduino, a couple of libraries are required – the matrix and GFX libraries. Be sure to install them in your sketchbook/libraries folder and not the usual location. When saving the library files, call the first folder Adafruit_LEDBackpack and the second Adafruit_GFX as they don’t arrive in that format.

Now for a quick demonstration, it’s simply one from the included library. The display is very bright, so I had to reduce the exposure on the camera which makes the background a little dark – but you get the idea:

A pair of those fitted to a dummy or doll would be quite interesting, or make good eyes for a 21st century “Metal Mickey”. Well that’s quite interesting, so how do you in fact display things on the matrix? I’ve deconstructed a few examples to show you how it’s done.

No matter what, you need to include the libraries, define the matrix object in the sketch and then start it with the matching I2C address – for example:

To scroll text across the display, modify the following chunk of code:

First, the setRotation() value is 0~3 and determines which way the text scrolls across the screen. This is useful if you mount the matrix in different positions, as you can still keep the text scrolling in a readable manner. Next, matrix.setTextWrap() – leave this as false,  as true displays each character and then just scrolls it in turn – looking rather odd. Now multiply the number of characters you want to display by 8, and replace the number -96 with negative your value and of course “Hello, world”. Finally follow with rest of the code. There’s a quick demonstration of this code in the sketch and video below:

 

Now for some graphics. You can define your own images (!) and store them in an array. Each arrays consists of eight bytes, each representing a row of the matrix. You can use binary to help visualise the results, for example:

and then to display that on the matrix, use the following:

… which resulted with:

crosshatch

To control individual pixels, send one or more of the following:

where x and y are the pixel’s coordinates (that fall between zero and seven), followed by:

Here’s a neat example sketch and video of a single pixel “running around the border”:

By this point you should be getting the hang of things now, so we’ll finish up with the last three graphic functions at once. To draw a line between x1, y1 and x2, y2 – use:

To draw a rectangle with corners at x1, y2, x2, y2 – use:

To draw a filled rectangle with corners at x1, y2, x2, y2 – use:

And to draw a circle with axis at x,y and a radius of r pixels – use:

Now we’ll put those functions into the following sketch and video:

 

If you want to get someone’s attention, you can blink whatever’s on the matrix at various frequencies – and of course turn it off. In the following function, use 0 for off, and 1~3 for different rates:

Finally, you can also adjust the brightness to one of sixteen levels (0~15) using:

That’s enough blinkiness for now. Remember the library is just shielding you from the raw I2C commands, so if you want to create your own functions or use a non-Arduino board – examine the library and the data sheet.

Conclusion

The backpack makes using the matrix an absolute breeze, and the library saves a lot of time and effort – leaving you to get on with creating your ideas into projects. You can get the matrix from adafruit and their distributors.

Full-sized images available on flickr.  And if you made it this far – check out my new book “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 – item purchased without notifying the supplier]

Posted in 16K33, adafruit, arduino, holtek, I2C, LED matrix, review, tutorialComments (0)

Tutorial: Arduino and the MSGEQ7 Spectrum Analyzer

This is a tutorial on using the MSGEQ7 Spectrum Analyser with Arduino, and chapter forty-eight of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 10/11/2014

In this article we’re going to explain how to make simple spectrum analysers with an Arduino-style board. (Analyser? Analyzer? Take your pick).

First of all, what is a spectrum analyser? Good question. Do you remember what  this is?

It’s a mixed graphic equaliser/spectrum analyser deck for a hi-fi system. The display in the middle is the spectrum analyser, and roughly-speaking it shows the strength of  different frequencies in the music being listened to – and looked pretty awesome doing it. We can recreate displays similar to this for entertainment and also as a base for creative lighting effects. By working through this tutorial you’ll have the base knowledge to recreate these yourself.

We’ll be using the MSGEQ7 “seven band graphic equaliser IC” from Mixed Signal Integration. Here’s the MSGEQ7 data sheet (.pdf).  This little IC can accept a single audio source, analyse seven frequency bands of the audio, and output a DC representation of each frequency band. This isn’t super-accurate or calibrated in any way, but it works. You can get the IC separately, for example:


and then build your own circuit around it… or like most things in the Arduino world – get a shield. In this case, a derivative of the original Bliptronics shield by Sparkfun. It’s designed to pass through stereo audio via 3.5mm audio sockets and contains two MSGEQ7s, so we can do a stereo analyser:

As usual Sparkfun have saved a few cents by not including the stackable header sockets, so you’ll need to buy and solder those in yourself. There is also space for three header pins for direct audio input (left, right and common), which are useful – so if you can add those as well.

So now you have a shield that’s ready for use. Before moving forward let’s examine how the MSGEQ7 works for us. As mentioned earlier, it analyses seven frequency bands. These are illustrated in the following graph from the data sheet:

freqresponse

It will return the strengths of the audio at seven points – 63 Hz, 160 Hz, 400 Hz, 1 kHz, 2.5 kHz, 6.25 kHz and 16 kHz – and as you can see there is some overlap between the bands. The strength is returned as a DC voltage – which we can then simply measure with the Arduino’s analogue input and create a display of some sort. At this point audio purists, Sheldonites and RF people might get a little cranky, so once again – this is more for visual indication than any sort of calibration device.

However as an 8-pin IC a different approach is required to get the different levels. The IC will sequentially give out the levels for each band on pin 3- e.g. 63 Hz then 160 Hz then 400 Hz then 1 kHz then 2.5 kHz then 6.25 kHz  then 16 kHz then back to 63 Hz and so on. To start this sequence we first reset the IC by pulsing the RESET pin HIGH then low. This tells the IC to start at the first band. Next, we set the STROBE pin to LOW, take the DC reading from pin 3 with analogue input, store the value in a variable (an array), then set the STROBE pin HIGH. We repeat the strobe-measure sequence six more times to get the rest of the data, then RESET the IC and start all over again. For the visual learners consider the diagram below from the data sheet:

strobing1

To demonstrate this process, consider the function

in the following example sketch:

If you follow through the sketch, you can see that it reads both left- and right-channel values from the two MSGEQ7s on the shield, then stores each value in the arrays left[] and right[]. These values are then sent to the serial monitor for display – for example:

If you have a function generator, connect the output to one of the channels and GND – then adjust the frequency and amplitude to see how the values change. The following video clip is a short demonstration of this – we set the generator to 1 kHz and adjust the amplitude of the signal. To make things easier to read we only measure and display the left channel:


Keep an eye on the fourth column of data – this is the analogRead() value returned by the Arduino when reading the 1khz frequency band. You can also see the affect on the other bands around 1 kHz as we increase and decrease the frequency. However that wasn’t really visually appealing – so now we’ll create a small and large graphical version.

First we’ll use an inexpensive LCD, the I2C model from akafugu reviewed previously. To save repeating myself, also review how to create custom LCD characters from here.

With the LCD with have two rows of sixteen characters. The plan is to use the top row for the levels, the left-channel’s on … the left, and the right on the right. Each character will be a little bar graph for the level. The bottom row can be for a label. We don’t have too many pixels to work with, but it’s a compact example:

lcdfullon

We have eight rows for each character, and the results from an analogueRead() fall between 0 and 1023. So that’s 1024 possible values spread over eight sections. Thus each row of pixels in each character will represent 128 “units of analogue read” or around 0.63 V if the Arduino is running from true 5 V (remember your AREF notes?). The sketch will again read the values from the MSGEQ7, feed them into two arrays – then display the required character in each band space  on the LCD.

Here’s the resulting sketch:

If you’ve been reading through my tutorials there isn’t anything new to worry about. And now for the demo, with sound –

That would look great on the side of a Walkman, however it’s a bit small. Let’s scale it up by using a Freetronics Dot Matrix Display – you may recall these from Clock One. For some background knowledge check the review here.  Don’t forget to use a suitable power supply for the DMD – 5 V at 4 A will do nicely. The DMD contains 16 rows of 32 LEDs. This gives us twice the “resolution” to display each band level if desired. The display style is subjective, so for this example we’ll use a single column of LEDs for each frequency band, with a blank column between each one.

We use a lot of line-drawing statements to display the levels, and clear the DMD after each display. With this and the previous sketches, there could be room for efficiency – however I write these with the beginner in mind. Here’s the sketch:

… and here it is in action:

Conclusion

At this point you have the knowledge to use the MSGEQ7 ICs to create some interesting spectrum analysers for entertainment and visual appeal – now you just choose the type of display enjoy the results. 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 fourth printing!) “Arduino Workshop”.

visit tronixlabs.com

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.

Posted in analyser, analyzer, arduino, BLIPTRONICS, com-10468, dev-10306, education, graphic, lesson, MSGEQ7, sparkfun, spectrum, tutorial

Tutorial: Arduino and TFT LCD

Old and now unsupported tutorial for 4D Systems 1.44″ TFT serial interface LCD.

Update 20/04/2013 

The Arduino library for this module hasn’t been updated to work with Arduino v1.0.1+ – so you need to use Arduino IDE v22 or v23. And the module itself has been discontinued. For the time being I’m leaving the tutorial here until a more suitable item can be used. We can’t help you with the 4D module

Nevertheless – if you have one – here’s the subject of the tutorial- the 4D Systems 1.44″ TFT serial interface LCD:

The LCD is an LED-backlit thin-film transistor type, resolution is 128 x 128 pixels, with an RGB colour range of 65536.

As an aside, this is a very powerful piece of hardware. The module not only contains a 1.44″ square TFT LCD, there is also a dedicated graphics processor and a microSD card interface. One can program the display processor in the same manner as another microcontroller platform for incredibly interesting results. For more information, please visit:

http://www.4dsystems.com.au/prod.php?id=120

However in the spirit of keeping things simple, this article will focus on driving the LCD directly using our Arduino or compatible boards. There are two firmware versions of this module – the GFX and the SGC. We need to have the SGC firmware, as this allows control via the serial TX/RX pins from our Arduno board. If you have purchased the SGC module, you’re ready to go. Scroll down until you see “And we’re back…”. However if you have the GFX version, please read the following instructions on how to change your LCD’s firmware from GFX to SGC…

Changing the firmware from GFX to SGC

  • At the moment this process only seems available to users of Microsoft Windows. All complaints to 4D Systems.
  • Unfortunately this process may not work with an Arduino Mega board.
  • First of all, remove the ATmega328 from your Arduino board. Please be careful, use a chip puller if possible. We are going to use the board as a simple serial-USB converter;
  • Insert your LCD module into a solderless breadboard;
  • Connect Arduino pin 0 (RX) to display pin 7 (RX); connect Arduino pin 1 (TX) to display pin 8 (TX). [Yes – TX>TX, RX>RX];
  • Connect Arduino 5V to display pin 9; connect Arduino GND to display pin 6; your LCD should display the following:

beforesgc

  • Visit http://www.4dsystems.com.au/prod.php?id=46, download and open the PmmC Loader application; visit http://www.4dsystems.com.au/prod.php?id=120 and download the .pmmc file to your local drive;
  • Connect your Arduino board via USB to the computer; then run the PmmC loader application;
  • Select the appropriate COM: port, load in the .pmmc file, then click Load. The firmware update should take less than sixty seconds;
  • When finished, you will be presented with the following on the computer:

progfinish

… and the following on your LCD:

aftersgcss

  • At this point unplug the USB lead from your Arduino board and all leads into the Arduino board;
  • Re-insert the ATmega328 back into your Arduino board;
  • Reconnect the wires from the LCD module to the Arduino, but this time connect Arduino TX to LCD RX; and LCD TX to Arduino RX.
  • Now you have  the serial-interface SGC firmware model LCD.

And we’re back…

To control this LCD, it requires commands to be sent via Serial.write(), and such commands are in the form of hexadecimal numbers. (You see something new every day). You can download the reference book with all the commands:

http://tronixstuff.com/wp-content/uploads/2011/02/goldelox-sgc-commands-sis-rev3.pdf

and bypass the library by directly writing the hexadecimal numbers directly to the module.

However, to get up to speed as fast as possible we can use a library with more of the popular functions included. Kudos and thanks to Oscar Gonzalez for writing a very useful library. Download the library from:

http://code.google.com/p/displayshield4d/downloads/list

and install into your ../Arduino-002x/libraries folder, then re-start the Arduino IDE if you had it running. You may be wondering why the library is named displayshield4d – the LCD manufacturer sells this LCD on an Arduino shield. Although that would be great for experimenting, one would need to purchase another standalone LCD if their project moved forward – myself included. So that’s why we’re using the bare LCD board.

To connect the LCD to our Arduino is very simple:

  • LCD pin 5 to Arduino RST;
  • LCD pin 6 to Arduino GND;
  • LCD pin 7 to Arduino D1;
  • LCD pin 8 to Arduino D0;
  • LCD pin 9 to Arduino 5V.

In the following examples we will demonstrate the various functions available in the library. As this is chapter 29, I will no longer explain the more basic functions or ideas that you should know by now, instead relying on comments within the sketch if it feels necessary. It can take a short moment for the LCD controller to process, so always put a short delay between functions.

When uploading a sketch to your Arduino you may need to disconnect the LCD from Arduino D0/D1 as it can interfere with the serial process.

Firstly we will demonstrate text display. Initialising the display requires a few functions:

The second line creates an instance of lcd to be used with the relevant functions. Next, within void setup():

To write text to the LCD, the following function is required:

This line sets the font transparency. If we use the parameter OLED_FONT_TRANSPARENT the unused pixels in the character area will be transparent and continue to show what they were set to before the text was over-written with. You can also use OLED_FONT_OPAQUE, which blocks the item displayed “behind” the text.

Whenever a function requires a colour parameter, we use:

where x, y and z are numerical values (between 0 and 255) for the red, green and blue components of the required colour. If you need an RGB numerical reference, download this handy chart. Finally, to display some text we use the following:

The parameters required are:

  • a – the x-position of the first character. E.g. if this was a zero, the top-left pixel of the first character would be on the left-most pixel column of the LCD;
  • b – the y-position of the first character. e.g. if both a and b were zero, the text would start from the top-left of the LCD;
  • c – numerical code for the font to use: 1 is for 5×7 pixel characters, 2 for 8×8 and 3 for 8×12;
  • the three values within the lcd.RGB() function determine the colour of the text;
  • d – x-axis resolution multiplier. E.g. if you double this and use the 5×7 font, the characters will be double-width;
  • e – y-axis resolution multiplier.

Now let’s see this in action with the following sketch:

And a short video clip of the example in action: – http://www.youtube.com/watch?v=t3yypXL022w

As you can see the display update speed is much better than the LCD from the previous chapter. Although this example was short, don’t be afraid to try out your own parameters in the example sketch.

Next we will demonstrate the various graphics functions in the library. Creating graphics isn’t rocket science, it just takes some imagination (something I admit to lacking) and following the parameters for each function. Our first is

which places a pixel on the screen at location x,y of colour described using lcd.RGB(). Next we have

which draws a line from x1, y1 to x2, y2 of colour rgb. One can also create rectangles and so on using

This will create a rectangle with the top-left point at x,y; width is l pixels, height is h pixels, and a new parameter z. If z is 0, the function will draw a solid shape, if z is 1, it will display only a wire-frame rectangle with a pixel width of one. Circles are created using

where x and y are the coordinates for the centre of the circle, r is the radius, and z is the solid/wireframe parameter. And finally – triangles:

This will draw a triangle with the corners at the coordinate parameters; z again is the solid/wireframe parameter. However you need to order the corners in an anti-clockwise order. This will become evident in the example sketch below. In this example we run through the graphical functions described above. By following through the sketch you should gain an idea of how the graphical functions are used, in order to create your own displays.

And here is the video of example 29.2 in action … brought to you by Mr Blurrycam: – http://www.youtube.com/watch?v=BKy-GuKWGZ8

 

Posted in 4d systems, arduino, education, LCD, learning electronics, lesson, microcontrollers, TFT, tutorial

Tutorial: Arduino and monochrome LCDs

Please note that the tutorials are not currently compatible with Arduino IDE v1.0. Please continue to use v22 or v23 until further notice. 

This is chapter twenty-four of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe.

The first chapter is here, the complete series is detailed here.

Welcome back fellow arduidans!

The purpose of this article is to summarise a range of affordable monochrome liquid-crystal display units that are available to work with our Arduino; and to replace the section about LCDs in chapter two of this series. We will first examine some fixed-character and then graphical LCD units in this article. So let’s go!

Fixed-character LCD modules

When shopping around for LCD modules, these will usually be the the most common found in retail outlets. Their size is normally measured by the number of columns and rows of characters in the display. For example, the three LCDs below are 8×2, 16×2 and 20×4 characters in size:

lcdtypesss

Currently, most LCDs should have a backlight of some sort, however you may come across some heavily-discounted models on (for example) eBay that are not. Character, background and backlight colours can vary, for example:

backlitsss

Interfacing these screens with our Arduino boards is very easy, and there are several ways to do so. These interface types can include four- and eight-bit parallel, three-wire,  serial, I2C and SPI interfaces; and the LCD price is usually inversely proportional to the ease of interface (that is, parallel are usually the cheapest).

Four-bit parallel interface

This is the cheapest method of interface, and our first example for this article. Your LCD will need a certain type of controller IC called a Hitachi HD44780 or compatible such as the KS0066. From a hardware perspective, there are sixteen pins on the LCD. These are usually in one row:

16pinsss

… or two rows of eight:

2by8pinsss

The pin labels for our example are the following:

  1. GND
  2. 5V (careful! Some LCDs use 3.3 volts – adjust according to LCD data sheet from supplier)
  3. Contrast
  4. RS
  5. RW
  6. Enable
  7. DB0 (pins DB0~DB7 are the data lines)
  8. DB1
  9. DB2
  10. DB3
  11. DB4
  12. DB5
  13. DB6
  14. DB7
  15. backlight + (unused on non-backlit LCDs) – again, check your LCD data sheet as backlight voltages can vary.
  16. backlight GND (unused on non-backlit LCDs)

As always, check your LCD’s data sheet before wiring it up.

Some LCDs may also have the pinout details on their PCB if you are lucky, however it can be hard to decipher:

Now let’s connect our example 16×2 screen to our Arduino using the following diagram.

Our LCD runs from 5V and also has a 5V backlight – yours may differ, so check the datasheet:

4bitparallel2

(Circuit layout created using Fritzing)

Notice how we have used six digital output pins on the Arduino, plus ground and 5V. The 10k ohm potentiometer connected between LCD pins 2, 3 and 5 is used to adjust the display contrast. You can use any digital out pins on your Arduino, just remember to take note of which ones are connected to the LCD as you will need to alter a function in your sketch. If your backlight is 3.3V, you can use the 3.3V pin on the Arduino.

From a software perspective, we need to use the LiquidCrystal() library. This library should be pre-installed with the Arduino IDE. So in the start of your sketch, add the following line:

Next, you need to create a variable for our LCD module, and tell the sketch which pins are connected to which digital output pins. This is done with the following function:

The parameters in the brackets define which digital output pins connect to (in order) LCD pins: RS, enable, D4, D5, D6, and D7.

Finally, in your void setup(), add the line:

This tells the sketch the dimensions in characters (columns, rows) of our LCD module defined as the variable lcd. In the following example we will get started with out LCD by using the basic setup and functions. To save space the explanation of each function will be in the sketch itself. Please note that you do not have to use an Arduino Mega – it is used in this article as my usual Arduino boards are occupied elsewhere.

And here is a quick video of the example 24.1 sketch in action:

There are also a some special effects that we can take advantage of with out display units – in that we can actually define our own characters (up to eight per sketch). That is, control the individual dots (or pixels) that make up each character. With the our character displays, each character is made up of five columns of eight rows of pixels, as illustrated in the close-up below:

pixels

In order to create our characters, we need to define which pixels are on and which are off. This is easily done with the use of an array (array? see chapter four). For example, to create a solid block character as shown in the image above, our array would look like:

Notice how we have eight elements, each representing a row (from top to bottom), and each element has five bits – representing the pixel column for each row. The next step is to reference the custom character’s array to a reference number (0~7) using the following function within void setup():

Now when you want to display the custom character, use the following function:

where 0 is the memory position of the character to display.

To help make things easier, there is a small website that does the array element creation for you. Now let’s display a couple of custom characters to get a feel for how they work. In the following sketch there are three defined characters:

And here is a quick video of the example 24.2 sketch in action:

So there you have it – a summary of the standard parallel method of connecting an LCD to your Arduino. Now let’s look at the next type:

Three-wire LCD interface

If you cannot spare many digital output pins on your Arduino, only need basic text display and don’t want to pay for a serial or I2C LCD, this could be an option for you. A 4094 shift register IC allows use of the example HD44780 LCD with only three digital output pins from your Arduino. The hardware is connected as such:

twilcd

And in real life:

exam24p3ss

From a software perspective, we need to use the LCD3Wire library, which you can download from here. To install the library, copy the folder within the .zip file to your system’s \Arduino-2x\hardware\libraries folder and restart the Arduino IDE. Then, in the start of your sketch, add the following line:

Next, you need to create a variable for our LCD module, and tell the sketch which of the 4094’s pins are connected to which digital output pins as well as define how many physical lines are in the LCD module. This is done with the following function:

Finally, in your void setup(), add the line:

The number of available LCD functions in the LCD3wire library are few – that is the current trade-off with using this method of LCD connection … you lose LCD functions but gain Arduino output pins. In the following example, we will demonstrate all of the available functions within the LCD3Wire library:

And as always, let’s see it in action. The LCD update speed is somewhat slower than using the parallel interface, this is due to the extra handling of the data by the 4094 IC:

Now for some real fun with:

Graphic LCD modules

(Un)fortunately there are many graphic LCD modules on the market. To keep things relatively simple, we will examine two – one with a parallel data interface and one with a serial data interface.

Parallel interface

Our example in this case is a 128 by 64 pixel unit with a KS0108B parallel interface:

glcdparallelss

For the more technically-minded here is the data sheet. From a hardware perspective there are twenty interface pins, and we’re going to use all of them. For breadboard use, solder in a row of header pins to save your sanity!

This particular unit runs from 5V and also has a 5V backlight. Yours may vary, so check and reduce backlight voltage if different.

You will again need a 10k ohm potentiometer to adjust the display contrast. Looking at the image above, the pin numbering runs from left to right. For our examples, please connect the LCD pins to the following Arduino Uno/Duemilanove sockets:

  1. 5V
  2. GND
  3. centre pin of 10k ohm potentiometer
  4. D8
  5. D9
  6. D10
  7. D11
  8. D4
  9. D5
  10. D6
  11. D7
  12. A0
  13. A1
  14. RST
  15. A2
  16. A3
  17. A4
  18. outer leg of potentiometer; connect other leg to GND
  19. 5V
  20. GND

A quick measurement of current shows my TwentyTen board and LCD uses 20mA with the backlight off and 160mA with it on. The display is certainly readable with the backlight off, but it looks a lot better with it on.

From a software perspective we have another library to install. By now you should be able to install a library, so download this KS0108 library and install it as usual. Once again, there are several functions that need to be called in order to activate our LCD. The first of these being:

which is placed within void setup(); The parameter sets the default pixel status. That is, with NON_INVERTED, the default display is as you would expect, pixels off unless activated; whereas INVERTED causes all pixels to be on by default, and turned off when activated. Unlike the character LCDs we don’t have to create an instance of the LCD in software, nor tell the sketch which pins to use – this is already done automatically. Also please remember that whenever coordinates are involved with the display, the X-axis is 0~127 and the Y-axis is 0~63.

There are many functions available to use with the KS0108 library, so let’s try a few of them out in this first example. Once again, we will leave the explanation in the sketch, or refer to the library’s page in the Arduino website. My creative levels are not that high, so the goal is to show you how to use the functions, then you can be creative on your own time. This example demonstrate a simpler variety of graphic display functions:

Now let’s see all of that in action:

You can also send normal characters to your KS0108 LCD. Doing so allows you to display much more information in a smaller physical size than using a character  LCD. Furthermore you can mix graphical functions with character text functions – with some careful display planning you can create quite professional installations. With a standard 5×7 pixel font, you can have eight rows of twenty-one characters each. Doing so is quite easy, we need to use another two #include statements which are detailed in the following example. You don’t need to install any more library files to use this example. Once again, function descriptions are in the sketch:

Again,  let’s see all of that in action:

If you’re looking for a very simple way of using character LCD modules, check this out.

LEDborder

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Posted in arduino, education, LCD, LCD-00710, learning electronics, lesson, microcontrollers, tutorialComments (52)


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