Led Grid Display
The feeling of gratification you get when your project finally started working and calls its daddy 😛
Keep scrolling, there’s something special for you at the end of the blog!
Umm let me start this in this way…
We all picked engineering for a reason and among most of us the main driving factor to become an engineer is that we love to innovate and we love to tinker with technology. I bet you that you’ve tinkered with almost each and every electronic toy you had in your childhood. And to be honest, Tony Stark👻 plays a major role in the creation of this innovative mindset for the current generation. This innovation and recreation instinct is what makes us an engineer and I’m sure so many of you are very enthusiastic to know more about Electronics culture in the campus.
So, if you’re Looking for a quick and easy weekend craft project, I’ve got you covered! Today I’ll show you how to make a Display! Calm down I’m not giving you an alternate display to watch movies when you’re free from your “gripping lectures”(IYKWIM 😜 ). I’m just taking you back to the good old days when solid state devices came into existence and replaced old high power consumption devices like vacuum tube diode, which were used for display purposes before the semiconductor devices came into existence. So, if you want to know more about the history of evolution of Display, I would love to tell you about it in brief and if you’re not in mood to go through the history, you can skip the history part and start learning about the project.
HISTORY of DISPLAYS:
With all of the advancements being made in display technology, it’s hard to believe that the knowledge used to create and develop this technology is over a hundred years old. In fact, the first baby steps into the field of display technology began as far back as 1897 when Karl Ferdinand Braun, a physicist and inventor, built the first Cathode-Ray Tube. This small tube would enable the very first televisions to be built and create an industry that has advanced in leaps and bounds from its humble beginnings.
The second major break in display technology came ten years after Karl Ferdinand Braun in 1907 with the discovery of Electroluminescence. This naturally occurring phenomenon would provide the first breakthrough for LED technology. 1952 saw the development of the very first curved screen display, and was installed in only a handful of movie theaters across the country. That technology would not be available to consumers for over fifty years.
The next big step forward in display history was the invention of the first LED bulb in 1961. Robert Biard and Gary Pittman patented the first infrared LED light for Texas Instruments. The very next year Nick Holonyack produced the first visible light LED. Two years later, in 1964, display technology took another leap with the invention of LCD and Plasma screens by American inventor James Fergason.
Even though touchscreen smartphone displays are relatively new technology, the first of these displays was invented as early as 1965 and was first used for air traffic controllers. Similarly HDTV really gets its start in Japan during the 1960s and 1970s, even though HDTVs don’t reach the U.S. until 1998. By the time you get to displays in the 90s, OLEDs have been invented by Kodak and we have the first full color plasma displays.
Incredibly, the display industry has rapidly expanded and will continue to do so. Displays of various sizes, forms and technology will be developed for diverse applications.
With it the necessity for accurate display testing systems will grow considerably as well. Konica Minolta has a number of display measurement systems available to meet the ever-changing needs in the display industry.
I think it’s enough about the history lets move to our project…
What The Hell You’re Talking About?
Er… the best example of the project which you’re about to build is Railway Station display board, Airport Displays, Sensex display board etc. and it is widely used as a cheap Display board around the world.
So, here we go….
Okay! Nice… So how it works?
What we are trying to build is a matrix made up of LEDs in which each Led will act as a working pixel(a minute area of illumination on a display screen, one of many from which an image is composed). By the help of this matrix we can display some basic characters. As the pixel spacing is not dense in our project, we can display only some basic characters.
The trick behind the display is multiplexing(I’m not explaining the details right here in the blog, you can contact me if you want to know more). It is basically a way to split information into little pieces and send it one by one. In this way you can save a lot of pins on the Arduino and keep your program quite simple. In a dot matrix display, multiple LEDs are wired together in rows and columns. This is done to minimize the number of pins required to drive them. We have 3 shift registers which multiply the number of outputs and save lots of Arduino pins.
Each shift register has 8 outputs and you only need 3 Arduino pins to control these shift registers.
I also used the 4017 decade counter to scan the rows, and you can scan up to 10 rows with it because you have only 10 outputs but to control it you need only 2 Arduino pins.
Required Circuit Elements:
- 144 LEDs
- 24 resistors( The value is determent by the type of LEDs, in my case 100 ohm)
- 4017 decade counter (It is an IC package commercially available in market)
- 1K Ohm resistors * 6
- 2N3904 transistors * 6 (Commonly used BJT for current amplification)
- A long Perfboard
- Arduino
- 3 x 74HC595 shift register
Now, let me explain you the requirement and use of each end every component in brief:
1) LEDs- we are using through hole leds as they are easy to handle, preferably use clear lens led, although my led grid was made up of diffused lens Leds.
2) Resistors-To limit voltage and current through Led, rating of led used is Forward voltage 2V, forward current= 20mA.
3) Decade counter - It is a serial digital counter that counts ten digits. The 4017 is a very useful chip and it’s a good idea to know how to work with it.
4) Arduino- It is an open-source platform used for building electronics projects. If you’re not familiar with Arduino I would suggest to follow the blog
5) Shift Registers- This is a memory storage device which is used in various way to reduce complexation of the hardware but increases complexation in coding. We are using it to reduce number of pins of microcontroller used.
Now enough theory you might get bored till now, so lets move on to the hardware implementation.
HOW TO MAKE LED MATRIX :
Soldering 144 LEDs in a matrix formation can be a little tricky if you don’t have a general idea how. You need to bend the positive lead of the LED down towards the other ones and make a column, and snip off the leads you didn’t use and try to make the connections as low as you can get, and you do this to all of the positive leads.
Negative leads are connected in a column and that’s make soldering tricky because the positive rows are in the way, so you will need to make a 90 degrees bend with the negative lead and make a bridge over the positive row to the next negative lead, and so on to the next LEDs.
NOW WE’LL MAKE THE CONTROL BOARD:
Follow this schematic to make the control board.
ARDUINO CODE:
Finally we’re about to use our display but before doing that we have to define characters to be displayed in a matrix and have to do a little bit of complex programming in Arduino . You can try it on your own and if you need any kind of help check out my Github account.
Future Extension of the project:
Now its high time to build something to show off. See you soon @ ArIES- Shivanshu Raj Shrivastava.
Contact Details:
Shivanshu Raj Shrivastava
ECE 2nd year
facebook.com/shivanshu1333
https://github.com/shivanshuIITR/LED-GRID
+91-9425646127
