EM83053DH Ver la hoja de datos (PDF) - ELAN Microelectronics

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EM83053DH

PC Microcontroller

ELAN Microelectronics 

EM83053DH

PC Micro-controller

the clock lines before the leading edge of the 10th clock, the keyboard should stop

sending, then buffer the data and return clock and data lines to high state.

6.4 Keyboard Data Input

When the system is ready to send data to the keyboard, it first checks clock line to see

if keyboard is sending data. If keyboard is not sending data or it is sending data but has

not reached the 10th clock, the system can inhibit the interface by forcing the clock line

low for more than 60 microseconds and prepares to send data. The keyboard checks

clock line status at least every 5 milliseconds. If a system Request to Send(RTS) is

detected, the keyboard clocks 11 bits in. After the 10th bit, the keyboard checks for a

high state in data line then pulls it low and clocks one more bit to signal the system that

data has been received. If data is low after the 10th bit, it indicates a frame error. The

keyboard should continue to count until data line goes high, then pulls it low and issues

a RESEND to the system.

6.5 Command from the System

The system can send commands to the keyboard at any time. The keyboard needs to

respond within 20 milliseconds, unless the system prevents keyboard output, when

doing self test or executing a RESET. The following are the keyboard input commands

and the actions that keyboard needs to take.

Set /Reset Status indicators ( Hex ED )

- Responds ACK.

- Receives option byte.

- Responds ACK.

- Updates status indicators.

- Returns to previous scanning state.

Echo ( Hex EEH )

- Responds with EE hex.

- Returns to previous scanning state.

Invalid commands ( Hex EF and F1 )

- Returns a RESEND command.

- Returns to previous scanning state.

4•

Product Specification (V1.0) 03.28.2003

(This specification is subject to change without further notice)

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