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Present PSM year 2012


PSM 1 Seminar

CAPACITIVE SENSING AND LED MESSAGING SYSTEMAHMAD LUTFI BIN SELAMATAE0701441Projek Sarjana Muda 1ContentIntroductionProblem BackgroundResearch QuestionObjectiveScope of the studyLiterature ReviewResearch MethodologyGantt ChartCurrent Progress and Expected ResultConclusionReferences

IntroductionConcept of capacitorPCBLED messaging systemProblem BackgroundThe production line.On the convey.

Research QuestionMaking capacitive touch sensor panel on PCBLED as the outputResearch 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 studyMaking the capacitive touch sensor. Act as switch.Use PIC16F84A as main controller.LED messaging as output or sign of alert to user.Literature ReviewTheoryThe capacitive sensor detect capacitance change.

humans touch give result value of 100 to 250 pF with body resistance from 1000 to 2000 ohmsBasic formula for calculating capacitance

Capacitive sensing using frequency change

theThe oscillator will oscillate a frequency.

The frequency changes when touched by finger

When capacitance increased, the frequency will decrease

Basic Construction of the capacitive sensorConcept is same as the normal capacitor.

Related product on the marketTouch Lamp


Research methodologyBlock diagram of systemCapacitive SensorFrequency changesMicrocontroller system: PIC16F84ALED Messaging displaySensor DevelopmentThe 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 PCBHardware and Circuit designDesigning the circuit using ProteusPIC circuitLED circuitSensor circuitProgramming software: MPLab softwareSystemCapacitive sensor pad 1 is a switch fo LED 1Capacitive sensor pad 2 is a switch fo LED 2Capacitive sensor pad 3 is a switch fo LED 3

Gantt Chart

Current ProgressModeling the concept design of capacitive sensor in Google SketchUp.

Find a capacitive sensor on the market for reference

Expected Result

DConclusionThe capacitive sensing is the other alternative to the mechanical switch

ReferencesBellis, M. (n.d.). Who Invented Touch Screen Technology? Retrieved October 21, 2011, from Inventors:, 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 :, C. (n.d.). Where Was the Touch Lamp Invented? Retrieved October 2011, 15, from eHow:, I. (2003). PCB Design. Retrieved November 7, 2011, from IBRT Scientific and Engineering Solitions:

Technology, M. (2004, May 17). PIC16F84A Data Sheet. Retrieved September 3, 2011, from Microchip Technology Inc. : Perme, M. T. (2007, July 12). AN1102, Layout and Physical Design Guidelines for Capacitive Sensing. Retrieved September 3, 2011, from Microchip Technology Inc.:, L. K. (2000, June 26). Capacitive Sensors. Retrieved September 5, 2011, from Capsense: (2010, April 1). Capacitive Touch Sensing Layout Guidelines. Retrieved Sepetember 13, 2011, from SEMTECH: