eKK8011
USB & PS/2 Keyboard Encoder
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.
6.1.5 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.
Select Alternate Scan Codes ( Hex F0 )
- Responds ACK.
- Clears output buffer.
- Sets the default typematic rate/delay.
- Clears last typematic key.
- Receives option byte.
Product Specification (V1.0) 06.10.2003
(This specification is subject to change without further notice)
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ELAN [ ELAN MICROELECTRONICS CORP ]
