HD64F2149 Datasheet, PDF (568/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

17.2 Register Descriptions
17.2.1 Keyboard Control Register H (KBCRH)
Bit
7
6
5
KBIOE KCLKI KDI
Initial value 0
1
1
Read/Write R/W
R
R
Note: * Only 0 can be written, to clear the flags.
4
KBFSEL
1
R/W
3
KBIE
0
R/W
2
KBF
0
R/(W)*
1
PER
0
R/(W)*
0
KBS
0
R
KBCRH is an 8-bit readable/writable register that indicates the operating status of the keyboard
buffer controller.
KBCRH is initialized to H'70 by a reset, and in standby mode, watch mode, subactive mode,
subsleep mode, and module stop mode. Bits 6, 5, and 2 to 0 are also initialized when KBIOE is
cleared to 0.
Bit 7—Keyboard In/Out Enable (KBIOE): Selects whether or not the keyboard buffer
controller is used. When KBIOE is set to 1, the keyboard buffer controller is enabled for
transmission and reception and the port pins function as KCLK and KD I/O pins. When KBIOE is
cleared to 0, the keyboard buffer controller stops functioning and the port pins go to the high-
impedance state.
Bit 7
KBIOE
0
1
Description
The keyboard buffer controller is non-operational (KCLK and KD signal pins have
port functions)
(Initial value)
The keyboard buffer controller is enabled for transmission and reception (KCLK
and KD signal pins are in the bus drive state)
Bit 6—Keyboard Clock In (KCLKI): Monitors the KCLK I/O pin. This bit cannot be modified.
Bit 6
KCLKI
0
1
Description
KCLK I/O pin is low
KCLK I/O pin is high
(Initial value)
534