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Input Devices

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Input Devices

• Keypad

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Input Devices

• Keypad

PT0 PT1 PT2 PT3

PT4

PT5

PT6

PT7

Port[0:3] = InputsVdd

Port[7:4] = OutputsPull one of

PT4, PT5, PT6, PT7 low

If a key is pressedThe associated PT[3:0] inputwill be pulled low

Scanning:Cycle through the outputs, check the inputs

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Input Devices

• Keypad

PT0 PT1 PT2 PT3

PT4

PT5

PT6

PT7

Port[0:3] = Inputs with pull-up turned on

Port[7:4] = OutputsPull one of

PT4, PT5, PT6, PT7 low

If a key is pressedThe associated PT[3:0] inputwill be pulled low

Scanning:Cycle through the outputs, check the inputs

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Input Devices

• Keyboard

• N x M matrix of switches

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Input Devices

• Keyboard

• N x M matrix of switches

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Input Devices

• Keyboard

• Mechanical Switches

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Input Devices

• Keyboard

• Mechanical Switches

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Input Devices

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Input Devices

• Keyboard• Controller

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Input Devices

• Keyboard

• Controller

• Performs debounce – 1-5ms typical

• Polling rate - < 200Hz

• Interface – USB, wireless, SPI, TWI

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Input Devices

• Mouse

• Opto-Mechanical

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Input Devices

• Mouse

• Opto-Mechanical

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Input Devices

• Mouse

• Opto-Mechanical

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Input Devices

• Mouse

• Opto-Mechanical

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Input Devices

• Mouse

• Optical Mouse

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Input Devices

• Mouse

• Optical Mouse

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Input Devices

• Mouse

• Optical Mouse Sensor

• By comparing images – direction and distance can be calculated

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Input Devices

• Mouse

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Input Devices

• Mouse

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Input Devices

• Mouse

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Input Devices

• Mouse

• Optical Mouse Sensor

• Output is a quadrature signal - just like a mechanical mouse

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Input Devices

• Mouse

• Optical Mouse Sensor

• Frame Rate: 1500 frames/sec

• Typical resolution: 400-800 cpi (counts/inch)

• Speed: 14ips (inches per second)

• Typical sensor dimension: 16x16 to 32x32

• Typical Path error: 0.5%

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Input Devices

• Mouse

• Optical Mouse Sensor

• Limited focal range