Present Psm

CAPACITIVE SENSING AND LED MESSAGING SYSTEM

AHMAD LUTFI BIN SELAMATAE070144

Content• Introduction• Problem Background• Research Question• Objective• Scope of the study• Literature Review• Research Methodology• Gantt Chart• Current Progress and Expected Result• Conclusion• References

Introduction• Concept of capacitor• PCB• LED messaging system

Problem Background• The production line.• On the convey.

Research Question• Making capacitive touch sensor panel on PCB• LED as the output

Research ObjectiveThe objective of the project as follow:• To construct a planar capacitive sensor on

printed circuit board (PCB)• To design and simulate the capacitive sensing

and LED messaging system circuit.• To construct a LED messaging system based a

panel of LED matrix.

Scope of the study• Making the capacitive touch sensor. Act as

switch.• Use PIC16F84A as main controller.• LED messaging as output or sign of alert to

user.

Literature ReviewTheory• The capacitive sensor detect capacitance

change. human’s touch give result value of 100 to 250 pF with body resistance from 1000 to 2000 ohms

• Basic formula for calculating capacitance

• Capacitive sensing using frequency change

the

• The oscillator will oscillate a frequency.

• The frequency changes when touched by finger

• When capacitance increased, the frequency will decrease

Basic Construction of the capacitive sensor

• Concept is same as the normal capacitor.

Related product on the market

• Touch Lamp

Hardware• PIC16F84A

Research methodology• Block diagram of system

Capacitive Sensor

Frequency changes

Microcontroller system:

PIC16F84A

LED Messaging display

Sensor Development• The size of sensor which is suitable to user.• The design of the sensor (square and circle)• The capacitance of the sensor

• Diameter of the circle is 1cm.

The layout of the sensor that will be printed on the PCB

Hardware and Circuit design• Designing the circuit using Proteus– PIC circuit– LED circuit– Sensor circuit

• Programming software: MPLab software

System• Capacitive sensor pad 1 is

a switch fo LED 1• Capacitive sensor pad 2 is

a switch fo LED 2• Capacitive sensor pad 3 is

a switch fo LED 3

Gantt Chart

Current Progress• Modeling the concept design of capacitive

sensor in Google SketchUp.

• Find a capacitive sensor on the market for reference

Expected Result

D

Conclusion• The capacitive sensing is the other alternative

to the mechanical switch

References• Bellis, M. (n.d.). Who Invented Touch Screen

Technology? Retrieved October 21, 2011, from About.com Inventors: http://inventors.about.com/od/tstartinventions/a/Touch-Screen.htm

• Kunen, S. M. (1987). Patent No. 4,668,877. United States of America.

• M.A. Kelly, G. S. (1993, November 15-19). An Investigation of Human Body Electrostatic Discharge. Retrieved November 15, 2011, from Automotive Electronics Council : www.aecouncil.com/Papers/aec1.pdf

• Pillow, C. (n.d.). Where Was the Touch Lamp Invented? Retrieved October 2011, 15, from eHow: http://www.ehow.com/facts_5997950_touch-lamp-invented_.html

• R.Tschaggelar, I. (2003). PCB Design. Retrieved November 7, 2011, from IBRT Scientific and Engineering Solitions: http://www.ibrtses.com/software/pcbdesign.html

• Technology, M. (2004, May 17). PIC16F84A Data Sheet. Retrieved September 3, 2011, from Microchip Technology Inc. : ww1.microchip.com/downloads/en/devicedoc/35007b.pdf

• Tom Perme, M. T. (2007, July 12). AN1102, Layout and Physical Design Guidelines for Capacitive Sensing. Retrieved September 3, 2011, from Microchip Technology Inc.: ww1.microchip.com/downloads/en/AppNotes/01102a.pdf

• Baxter, L. K. (2000, June 26). Capacitive Sensors. Retrieved September 5, 2011, from Capsense: www.capsense.com/capsense-wp.pdf

• SEMTECH. (2010, April 1). Capacitive Touch Sensing Layout Guidelines. Retrieved Sepetember 13, 2011, from SEMTECH: http://www.semtech.com/images/datasheet/capacitive-touch-sensing-layout-guidelines-an.pdf