HD404318 Datasheet, PDF (24/66 Pages) Hitachi Semiconductor – 4-bit HMCS400-series microcomputer

HD404318 Series
I/O Ports
The MCU has 33 input/output pins (D₀–D₈, R0–R4, R8) and one input-only pin (RA₁). The following
describes the features of the I/O ports.
• The 21 pins consisting of D₀–D₈, R1, R2, and R8 are all high-voltage I/O pins. RA₁ is a high-voltage
input-only pin. These high-voltage pins can be equipped with or without pull-down resistance, as
selected by the mask option.
• All standard output pins are CMOS output pins. However, the R0₂/SO pin can be programmed for
NMOS open-drain output.
• In stop mode, input/output pins go to the high-impedance state
• All standard input/output pins have pull-up MOS built in, which can be individually turned on or off by
software
Table 5 Control of Standard I/O Pins by Program
MIS3 (bit 3 of MIS)
DCR
PDR
CMOS buffer PMOS
NMOS
Pull-up MOS
Note: — indicates off.
0
1
0
1
0
1
0
1
0
1
0
1
0
1
—
—
—
On
—
—
—
On
—
—
On
—
—
—
On
—
—
—
—
—
—
On
—
On
Data control register (DCR0: $030, DCR3: $033, DCR4: $034)
DCR0, DCR3,
DCR4
Bit
3
2
1
0
Initial value
0
0
0
0
Read/Write
W
W
W
W
Bit name
DCR03, DCR02, DCR01, DCR00,
DCR33, DCR32, DCR31, DCR30,
DCR43, DCR42, DCR41, DCR40
Bits 0 to 3 CMOS Buffer Control
0
CMOS buffer off
(high impedance)
1
CMOS buffer on
Correspondence between ports and DCR bits
Register Bit 3 Bit 2 Bit 1 Bit 0
DCR0
DCR3
DCR4
R0₃
R0₂
R0₁
R0₀
R3₃
R3₂
R3₁
R3₀
R4₃
R4₂
R4₁
R4₀
Figure 17 Data Control Register (DCR)
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