Projects (USIU)/ledmatrixdisplay
CONTRIBUTING MEMBERS:
KALPAVRIKSHIKA SELVAKUMAR
ID: 640631
& SAMUEL NJUGUNA
ID: 640613
ASSIGNMENT:
LED MATRIX DISPLAY
INSTRUCTOR:
DR.SILVESTER NAMUYE
COURSE:
APT 2030
Figure 1: Raspberry Pi model B+. 1
Requirements to do the work/Apparatus. 2
Figure 2: Simulated setup of LED matrix. 3
Contents
Abstract
This project was issued by the instructor to help the participants apply digital circuitry with the raspberry pi. The raspberry pi is a versatile micro-computer. With the raspberry pi as a controller, a digital display was to be assembled using an array of single LEDs – an LED matrix. This LED matrix would then be controlled by the raspberry pi. Control instructions were written in python programming language. The first setup of the circuit was connected on a standard breadboard for testing purposes. The circuit was then transferred onto an empty PCB and soldered on.
The project yielded positive results and the students were able to create patterns of their choice on the LED matrix display.
In the future, the project will be expanded for commercial use as well as implemented on campus for short-term announcements.
Introduction
The Raspberry Pi is a low cost computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. It’s capable of doing everything that a desktop computer can do, from browsing the internet and playing high-definition video, to making spreadsheets, word-processing, and playing games. (What is a Raspberry Pi?, 2015)
The Raspberry Pi has the ability to interact with the outside world, and has been used in a wide array of digital maker projects, from music machines and parent detectors to weather stations and tweeting birdhouses with infra-red cameras.The raspberry pi runs on a software called the “Raspbian” and its native language is python.
Figure 1: Raspberry Pi model B+
In a matrix format LEDs are arranged in rows and columns. You can also think of them as y and x coordinates. Let’s assume we have 4×4 matrix. Rows would be marked from A to D and columns from 1 to 4. Now we can address each LED by row and column. Top left led would be (A,1). Bottom down led would be (D, 4).
Objective
The objective of this experiment was to demonstrate how the Raspberry Pi can be used to control a digital circuit, specifically an LED matrix. This control was to be used to display patterns on the LED matrix with the use of python as the programming language.
Requirements to do the work/Apparatus
Apparatus
- Raspberry Pi
- T-cobbler
- Connecting wires
- Bread-board
- Empty PCB
- 12 ohm resistors
- LEDs
Tools
- Soldering Kit
- Multi-meter
- Wire-cutter
Figure 2: Simulated setup of LED matrix
Experimental setup
Figure 3: Experimental setup
Procedure
- The circuit was connected as shown above
- The T-Cobbler was then connected to the raspberry pi
- The observations of the patterns were then noted
Observations and results
Figure 4: Display of the letter ‘C’.
Figure 5: Display of the letter 'H'
Figure 6: Display of the letter 'A'
Figure 7: Display of the letter 'K'
The above demonstrated displays where intended to spell out the word “HACK” using the LED matrix. It was successful.
Discussion
The concept vital to the success of this project was “persistence of vision”.Persistence of vision is a commonly-accepted although somewhat controversial theory which states that the human eye always retains images for a fraction of a second (around 0.04 second). This means that everything we see is a subtle blend of what is happening now and what happened a fraction of a second ago(Media, 2015). To make a pattern, each row is lit at a time and this done at a delay of 0.001seconds and this causes persistence of vision to occur. With persistence of vision all rows are perceived to be lighting at the same time.
Conclusion
The Project was a success in displaying patterns on a LED matrix controlled by the Raspberry Pi. However, there was some issues with the soldering onto the PCB which will be dealt with in future.
Recommendation
- In future, the LED matrix would be enlarged for more clear patterns.
- Input improvements like wireless input among other will be developed.
- Use of RGB LEDs for a variety colors for better effect
- Use of shift registers give a better effect as the message would move horizontally.
References
What is a Raspberry Pi? (2015). (R. P. Foundation, Producer) Retrieved from What is a Raspberry Pi?: https://www.raspberrypi.org/help/what-is-a-raspberry-pi/
Media, W. (2015). Persistence of Vision. Retrieved 2015, from http://www.mediacollege.com: http://www.mediacollege.com/glossary/p/persistence-of-vision.html
