King Billion Electronics Co., Ltd

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HE847701

HE80000 SERIES

March 26, 2004

Page 16 of 29

V1.03

This specification is subject to change without notice. Please contact sales person for the latest version before use.

OP1

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Field

DRDY

STOP

SLOW

INTE

T2E

T1E

Z

C

Mode

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

Reset

1

0

0

0

0

0

-

-

OP2

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Field

IDLE

PNWK

TCWK

TBE

TBS[3..0]

Mode

R/W

R

R

R/W

W

W

W

W

Reset

0

-

-

0

-

-

-

-

If the dual clock mode is used, the LCD display, Timer1 and Timer Base will derive its clock source from

slow clock while the other blocks will operate with the fast clock.

9. General Purpose I/O

There are three dedicated general purpose I/O port, PRTC, PRTD and PRT10, while PRT14, PRT15 and

PRT17 are multiplexed with LCD segment driver pins. All the I/O Ports are bi-directional and of non-

tri-state output structure. The output has weak sourcing (50 µA) and stronger sinking (1 mA) capability

and each can be configured as push-pull or open-drain output structure individually by mask option.

When the I/O port is used as input, the weakly high sourcing can be used as weakly pull-up. Open drain

can be used if the pull-up is not required and let the external driver to drive the pin. Please note that a

floating pad could cause more power consumption since the noise could interfere with the circuit and

cause the input to toggle. A ‘1’ needs to be written to port first before reading the input data from the I/O

pin. If the PMOS is used as pull-up, care should be taken to avoid the constant power drain by DC path

between pull-up and external circuit.

The input port has built-in Schmidt trigger to prevent it from chattering. Hysteresis level of Schmidt

trigger is 1/3*VDD.

VDD

VDD

Q

Q'

LATCH

MO_?PP

SCHMIDT Trigger input

DOUT

PAD

DIN