GMS87C1102 datasheet(41/89 Pages) HYNIX

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GMS81C1102 / GMS81C1202

Jan. 2002 ver 2.0

13. I/O PORTS

The GMS81C1202 has three ports, RA, RB and RC. These

ports pins may be multiplexed with an alternate function

for the peripheral features on the device. In general, when

a initial reset state, all ports are used as a general purpose

input port.

All pins have data direction registers which can set these

ports as output or input. A “1” in the port direction register

defines the corresponding port pin as output. Conversely,

write “0” to the corresponding bit to specify as an input

pin. For example, to use the even numbered bit of RA as

output ports and the odd numbered bits as input ports, write

“55H” to address C1H (RA direction register) during initial

setting as shown in Figure 13-1.

Reading data register reads the status of the pins whereas

writing to it will write to the port latch.

Figure 13-1 Example of port I/O assignment

13.1 RA and RAIO registers

RA is an 8-bit bidirectional I/O port (address C0H). Each

port can be set individually as input and output through the

RAIO register (address C1H).

RA7~RA1 ports are multiplexed with Analog Input Port

( AN7~AN1 ) and RA0 port is multiplexed with Event

Counter Input Port ( EC0 ).

Figure 13-2 Registers of Port RA

The control register RAFUNC (address CAH) controls to

select alternate function. After reset, this value is "0", port

may be used as general I/O ports. To select alternate func-

tion such as Analog Input or External Event Counter Input,

write "1" to the corresponding bit of RAFUNC.Regardless

of the direction register RAIO, RAFUNC is selected to use

as alternate functions, port pin can be used as a correspond-

ing alternate features ( RA0/EC0 is controlled by RB-

FUNC )

I : INPUT PORT

WRITE "55H" TO PORT RA DIRECTION REGISTER

RA DATA

RB DATA

RA DIRECTION

RB DIRECTION

C0H

C1H

C2H

C3H

76543210

BIT

76543210 PORT

O : OUTPUT PORT

RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0

INPUT / OUTPUT DATA

RA Data Register

ADDRESS : C0H

RESET VALUE : Undefined

ANSEL0

RA Function Selection Register

RAFUNC

ADDRESS : CAH

RESET VALUE : 00000000

ANSEL7

ANSEL1

ANSEL2

ANSEL3

ANSEL4

ANSEL5

ANSEL6

0 : RB0

1 : AN0

0 : RA1

1 : AN1

0 : RA2

1 : AN2

0 : RA3

1 : AN3

0 : RA4

1 : AN4

0 : RA5

1 : AN5

0 : RA6

1 : AN6

0 : RA7

1 : AN7

0 : INPUT PORT

1 : OUTPUT PORT

DIRECTION SELECT

RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0

RA Direction Register

RAIO

ADDRESS : C1H

RESET VALUE : 00000000

PORT

RAFUNC.7~0

Description

RA7/AN7

RA7 ( Normal I/O Port )

AN7 ( ADS2~0=111 )

RA6/AN6

RA6 ( Normal I/O Port )

AN6 ( ADS2~0=110 )

RA5/AN5

RA5 ( Normal I/O Port )

AN5 ( ADS2~0=101 )

RA4/AN4

RA4 ( Normal I/O Port )

AN4 ( ADS2~0=100 )

RA3/AN3

RA3 ( Normal I/O Port )

AN3 ( ADS2~0=011 )

RA2/AN2

RA2 ( Normal I/O Port )

AN2 ( ADS2~0=010 )

RA1/AN1

RA1 ( Normal I/O Port )

AN1 ( ADS2~0=001 )

RA0/EC01

1. This port is not an Analog Input port, but Event Counter

clock source input port. ECO is controlled by setting

TOCK2~0 = 111.

The bit RAFUNC.0 (ANSEL0) controls the RB0/AN0/AVref

port ( Refer to Port RB).

RA0 ( Normal I/O Port )

EC0 ( T0CK2~0=111 )

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