Interfacing of Matrix Keyboard with 8051

Keyboards , LCDs most widely used input/output devices of the 8051

Contents to be covered: keyboard fundamentals key press and key detection mechanisms Details of keyboard interfacing to 8051.

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Key closure detection

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C1

R1P2.0

P2.4 805

1

Key not pressed

1

C1

R1P2.0

P2.4

8051

Key pressed

Keyboard interfacing with 8051

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Interfacing the Keyboard with 8051 Keyboards organized in a matrix of rows and

columns. The CPU accesses both rows and column through

ports When a key pressed, a row and column make a

connect; otherwise, there is no connection between row and column.

Microcontroller scans the keys continuously to identify which one has been activated

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