Presentation 40x16 LED SCROLL (1)

7/31/2019 Presentation 40x16 LED SCROLL (1)

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Bad driver Feedback display

40x16 LED matrix display

https://docs.google.com/?pli=1#folders/0B5vWPuxrsdbDZjMyNjI0YWItZTg0OC00NzZjLTllZDItNDUyNjc2NTQ5ZDk5

Documentation and Project files @
https://docs.google.com/?pli=1#folders/0B5vWPuxrsdbDZjMyNjI0YWItZTg0OC00NzZjLTllZDItNDUyNjc2NTQ5ZDk5https://docs.google.com/?pli=1#folders/0B5vWPuxrsdbDZjMyNjI0YWItZTg0OC00NzZjLTllZDItNDUyNjc2NTQ5ZDk5https://docs.google.com/?pli=1#folders/0B5vWPuxrsdbDZjMyNjI0YWItZTg0OC00NzZjLTllZDItNDUyNjc2NTQ5ZDk5https://docs.google.com/?pli=1#folders/0B5vWPuxrsdbDZjMyNjI0YWItZTg0OC00NzZjLTllZDItNDUyNjc2NTQ5ZDk5


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Idea

How it came into my mindThe project was made fordisplaying it on the rear glassshield of the car. It is designed insuch a way that it will not obstruct

the view for rear viewing mirrorand also could display text andimages to the following car.the idea came to my mind as oftendriving on highway it was required

to give feedback to other (BAD)drivers, who does not followhighway rules...( Grrrrrrr )


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Introduction

Intro:LED matrix display has many variants, in terms of row andcolumns, types of LEDs, packing and the way they are driven.

and application also.


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Step 1 : Making of LED Matrix

Dimensions:the rear wind shield of my car ( volkswagonpolo )is approx 104x38 cm. So I decided togrid to 2 cm by 2cm. this will make it aalmost cover whole that are of sheild and

also grid is enough big so that it will notobstruct the view.


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Rows and Columns:Looking into the way to drive these ledsand how to handle the program I concludedthat it should be multiple of 8 ( as 74hc595was decided )

I tried to get free sample from TI forMAX6952 and MAX6953 5x7 LED Driversbut vain. So i decided to make my owndrivers.

so the final grid was of 40x16 leds. thismeans 5 chips on col and 2 chips on rows.


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Dye for matrix:Since I wanted the spacing between LED tobe perfect so i created a holder for the ledand soldered them. This gave a goodresults in terms of spacing consistency. It

was a waste piece of wood. Made slots in itas per led dimensions and theninserted leds in it bending there legs andthen soldering it. step by step I madeit modular process and it took two full daysto make full matrix. It may sound large time

but believe me it will take that....


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Step 2 : LED Driver Circuit

Driver for LED:Since I did some research on how to drive led and matrix.. so the easy and cheap way come

to me was 74HC595 8-bit serial-in, serial or parallel-out shift register withoutput latches; 3-state. In above diagram there is a example of driving 8 rows.Similar it was extended for 16 rows.


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since I wanted it to havemaximum transparency so I decided toomit the PCB for this and solder thecomponents directly to the LED's.though it is not such a good option but i

am happy with the result.. once done idont need to move it alot..


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attaching all the components and dongwiring to it. the output was not as great iexpected. but it was good for testingand prototyping.. the wires were lookingvery messy and not neat. may be

should use thinner wires that may givesome neat results... but still i go ahaeadwith this and created a program fordriving this.


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Finally I run a test program to test allthe LED . the output was thrilling andwas happy to see the results


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Step 3 : Programming

Programming was done in assemblylanguage and AT89C51 was used.Since it has limited RAM and ROM,managing resources became difficultwith time as I was proceeding with

code.

I used Scratch pad ram for static Imageof led. Timers for polling rowsdata. Interrupt for changing staticimages images. Data base in ROM forcharacter generation and images...


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Step 3 : Programming

To run all the led was easy but to display some patterns required lots ofTRICKS and special techniques for performance. Since I was using lowspeed processor. So it took lots of performance tuning was done.


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Final output

I was able to do lots of pattern and animations. text scrolling and smoothscrolling. etc etc.. there is a small video to show you results.

https://picasaweb.google.com/lh/photo/BZinW0J5OGr8WPkTF3-

wcg?feat=directlink

https://picasaweb.google.com/lh/photo/_yIWMwC6DRjNl4BuxLqHtg?feat=directlink

Video 1

Video 2


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Final output

Then it was installed on the back of car. currently it is showing hard code text but ihave plans to update it from mobile via bluetooth, so that i can provide feedbackto the following cars

https://picasaweb.google.com/104475112007830201673/LEDScroll#5664

874113381340482

https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306

Video 3

Video 4
https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874298273614306https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482https://picasaweb.google.com/104475112007830201673/LEDScroll#5664874113381340482

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Presentation 40x16 LED SCROLL (1)