HMS87C1808B Datasheet, PDF(44/99 Page) List of Unclassifed Manufacturers

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HMS87C1808B Datasheet, PDF (44/99 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

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HMS87C1X04B/08B/16B

9.4 RD and RDIO registers

RD is an 8-bit bidirectional I/O port (address C6H). Each pin can

be set individually as input and output through the RDIO register

(address C7H).

RD Data Register

ADDRESS : C6H

RESET VALUE : Undefined

RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0

Pull-up Selection Register

PUPSEL

ADDRESS : CCH

RESET VALUE : ----_0000

PUP3 PUP2 PUP1 PUP0

INPUT / OUTPUT DATA

RD Direction Register

RDIO

ADDRESS : C7H

RESET VALUE : 0000_0000

DIRECTION SELECT

0 : INPUT PORT

1 : OUTPUT PORT

RD Function Selection Register

RDFUNC

RD1 / INT3 Pull-up

0 : No Pull-up

1 : With Pull-up

RD0 / INT2 Pull-up

0 : No Pull-up

1 : With Pull-up

Interrupt Edge Selection Register

IEDS

ADDRESS : E6H

RESET VALUE : 0000_0000

IED3H IED3L IED2H IED2L IED1H IED1L IED0H IED0L

INT3

INT2

INT1

INT0

ADDRESS : CDH

RESET VALUE : 0000_0000

External Interrupt Edge Select

00 : Normal I/O port

01 : Falling (1-to-0 transition)

10 : Rising (0-to-1 transition)

1 1: Both (Rising & Falling)

INT3I

INT2I

0 : RD0

1 : INT2

0 : RD1

1 : INT3

Figure 9-5 Registers of Port RD

In addition, Port RD is multiplexed with external interrupt input

function. The control register RDFUNC (address CDH) controls

to select alternate function. After reset, this value is â0â, port may

be used as general I/O ports. To select alternate function, write

â1â to the corresponding bit of RDFUNC.

Regardless of the direction register RDIO, RDFUNC is selected

to use as external interrupt input function, port pin can be used as

a interrupt input feature.

9.5 RE and REIO registers

RE is a 7-bit bidirectional I/O port (address C8H). Each pin can

be set individually as input and output through the REIO register

(address C9H).

RE Data Register

ADDRESS : C8H

RESET VALUE : Undefined

- RE6 RE5 RE4 RE3 RE2 RE1 RE0

RE Direction Register

REIO

ADDRESS : C9H

RESET VALUE : -000_0000

INPUT / OUTPUT DATA

DIRECTION SELECT

0 : INPUT PORT

1 : OUTPUT PORT

Figure 9-6 Registers of Port RE

SEP. 2004 Ver 1.03

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