VR4102 datasheet(428/701 Pages) NEC

428 / 701 page

CHAPTER 21 KIU (KEYBOARD INTERFACE UNIT)

428

Details of the status of the KIU sequencer are described below.

• Scanning:

This is the state where the scan sequencer performs key scan to load key data.

• Interval next scan:

This is the state where the scan of a set of key data

Note has completed and waiting for

the start of the next key scan. The interval after the completion of the scan of a set of

key data until the start of the next scan is set on the KIUWKIREG.

Note The number of data bits depends on the number of KSCAN pins used as below.

The number of KSCAN pins is set in SCANLINE register.

KSCAN pins

Number of data bits

64 bits

80 bits

96 bits

• Wait Key in:

This is the state of waiting for key input in the key auto scan mode. When the scan

sequencer is enabled while ATSCAN bit of KIUSCANREP register is set to 1, the

VR4102 waits for key input in this state. In this case, all outputs of the KSCAN pins

Note

are in high level.

When shifting the CPU to Suspend mode (or Standby mode with

TClock masked), be sure to set the KIU to the auto scan mode before the shift and

confirm that the sequencer in the Wait key in state.

Note The number of pins is set in LINE[1..0] bits of SCANLINE register as below.

LINE[1..0]

Number of KSCAN pins

• Stopped:

This is the state where the sequencer is disabled.

VR4102 Datasheet(PDF) 428 Page - NEC