HMS87C1304A Datasheet, PDF (29/70 Pages) Hynix Semiconductor – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

HYUNDAI MicroElectronics
HMS87C1304A/HMS87C1302A
9. I/O PORTS
The HMS87C1304A and HMS87C1302A has four ports,
RA, RB, RC and RD. 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
“55_H” to address C1_H (RA direction register) during initial
setting as shown in Figure 9-1 .
Reading data register reads the status of the pins whereas
writing to it will write to the port latch.
WRITE “55H” TO PORT RA DIRECTION REGISTER
C0H
C1H
C2H
C3H
RA DATA
RA DIRECTION
RB DATA
RB DIRECTION
01010101
7 6 5 4 3 2 1 0 BIT
IOIOIOIO
7 6 5 4 3 2 1 0 PORT
I: INPUT PORT
O: OUTPUT PORT
Figure 9-1 Example of port I/O assignment
9.1 RA and RAIO registers
RA is an 8-bit bidirectional I/O port (address C0_H). Each
port can be set individually as input and output through the
RAIO register (address C1_H).
y _{RA7~RA1 ports are multiplexed with Analog Input Port}
r _{(AN7~AN1) and RA0 port is multiplexed with Event}
a _{Counter Input Port (EC0).}
in ^{RA Data Register}
ADDRESS : C0H
RESET VALUE : Undefined
RA
RA7 RA6 RA5 RA4 RA3 RA2 RA1 RA0
lim _{RA Direction Register}
Pre ^RAIO
INPUT / OUTPUT DATA
ADDRESS : C1H
RESET VALUE : 00000000
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)
PORT
RA7/AN7
RA6/AN6
RAFUNC.7~0
Description
0
RA7 (Normal I/O Port)
1
AN7 (ADS2~0=111)
0
RA6 (Normal I/O Port)
1
AN6 (ADS2~0=110)
0
RA5 (Normal I/O Port)
DIRECTION SELECT
0 : INPUT PORT
RA5/AN5
1
AN5 (ADS2~0=101)
1 : OUTPUT PORT
0
RA4 (Normal I/O Port)
RA4/AN4
RA Function Selection Register
ADDRESS : CAH
1
AN4 (ADS2~0=100)
RAFUNC
RESET VALUE : 00000000
0
RA3 (Normal I/O Port)
ANSEL7 ANSEL6 ANSEL5 ANSEL4 ANSEL3 ANSEL2 ANSEL1 ANSEL0
RA3/AN3
1
AN3 (ADS2~0=011)
0 : RA4
1 : AN4
0 : RA5
1 : AN5
0 : RA6
1 : AN6
0 : RA7
1 : AN7
0 : RB0
1 : AN0
0 : RA1
1 : AN1
0 : RA2
1 : AN2
0 : RA3
1 : AN3
RA2/AN2
RA1/AN1
RA0/EC0¹
0
RA2 (Normal I/O Port)
1
AN2 (ADS2~0=010)
0
RA1 (Normal I/O Port)
1
AN1 (ADS2~0=001)
RA0 (Normal I/O Port)
EC0 (T0CK2~0=111)
Figure 9-2 Registers of Port RA
The control register RAFUNC (address CA_H) controls to
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).
Jan. 2001
Preliminary
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