HD404618 Datasheet, PDF (37/89 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
Input/Output
The MCU provides 26 input/output pins and 4 input pins, including 10 high-current pins (15 mA, max.). A
program-controlled pull-up MOS transistor is provided for each input/output pin.
The output buffer is turned on and off by the data control register (DCR) during input through an
input/output pin.
I/O pin circuit types are shown in table 19.
D Ports (D₀–D₁₃): Consist of ten 1-bit input/output pins and four input pins. Pins D₀–D₉ are high-current
I/O pins (15 mA, max.). The sum current of the pins can go up to 100 mA. These pins are set by the SED
and SEDD instructions, reset by the RED and REDD instructions, and tested by the TD and TDD
instructions. Output data is stored in the port data register.
The on/off status of the output buffer is controlled by D port data control registers (DCRB, DCRC, and
DCRD) that are mapped to the memory address area. Pins D₁₀–D₁₃ are input-only pins.
Two operating modes are available to pins D₁₂ and D₁₃: digital input mode and analog input mode. The
operating modes are set by bits 0 and 1 of port mode register B (PMRB). In the digital input mode, these
pins can be used as input pins with the same input characteristics as the I/O pins. In the analog input mode,
the result of a comparison with the reference voltage can be read as input data. The reference voltage is
input by the D₁₁/VC_ref pin.
R Ports: Consist of sixteen 4-bit I/O ports. Data is input to these ports by the LAR and LBR instructions
and output from them by the LRA and LRB instructions.
The on/off status of the output buffers of the R ports are controlled by R port data control registers (DCR0–
DCR3) that are mapped to memory addresses.
Pins R0₀, R0₁, and R0₂ are multiplexed with pins SCK, SI, and SO, respectively.
Pins R3₁, R3₂, and R3₃ are multiplexed with TIMO, INT₀, and INT₁, respectively. Refer to figure 24.
Pull-Up MOS Transistor Control: A program-controlled pull-up MOS transistor is provided for each
input/output pin.
The on/off status of all these transistors is controlled by bit 3 of port mode register B (PMRB), and the
on/off status of an individual transistor can also be controlled by the port data register (PDR) of the
corresponding pin. This enables on/off control of each individual pin. Refer to table 20.
The on/off status of each transistor and the peripheral function mode of each pin can be set independently.
How to Deal with Unused I/O Pins: I/O pins that are not needed by the user system must be connected to
V_CC to prevent LSI malfunctions due to noise. These pins must either be pulled up to V_CC by their pull-up
transistors or by resistors of about 100 kΩ.
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