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Keypads are small keyboards that are used to enter numeric, alphanumeric or select configuration data to microcontroller systems. Keypads are available in a variety of sizes. The common sizes are 3x3, 4x3 and 4x4 keypads. A matrix keypad is basically a combination of push-buttons in a way to form rows and columns. In this way the number of input/output pins necessary for their connection to a microcontroller is reduced. A 4x3 keypad requires 7 input/output pins instead of 12 and a 4x4 will require 8 input/output pins instead of 16 pins. Keypad is a widely used input device with lots of application in our everyday life: Telephone, ATM, electronic lock, Calculator, Industrial process, Timers etc. In this article, we are going to learn how to interface a matrix keypad with an LCD display using MikroC Pro for PIC compiler.
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