HD6433308 Datasheet, PDF (98/349 Pages) Hitachi Semiconductor – Hitachi Single-Chip MicroComputer

MOS Pull-Ups: Are available for input pins in modes 2 and 3. Software can turn on the MOS
pull-up by writing a “1” in P2DR, and turn it off by writing a “0.” The pull-ups are automatically
turned off for output pins in modes 2 and 3, and for all pins in mode 1.
Mode 1: In mode 1 (expanded mode without on-chip ROM), port 2 is automatically used for
address output. The port 2 data direction register is unwritable. All bits in P2DDR are
automatically set to "1" and cannot be cleared to "0."
Mode 2: In mode 2 (expanded mode with on-chip ROM), the usage of port 2 can be selected on a
pin-by-pin basis. A pin is used for general-purpose input if its data direction bit is cleared to "0,"
or for address output if its data direction bit is set to “1.”
Mode 3: In the single-chip mode port 2 is a general-purpose input/output port.
Reset: A reset clears P2DDR and P2DR to all “0,” placing all pins in the input state with the MOS
pull-ups off. In mode 1, when the chip comes out of reset, P2DDR is set to all "1."
Hardware Standby Mode: All pins are placed in the high-impedance state with the MOS pull-ups
off.
Software Standby Mode: In the software standby mode, both P2DDR and P2DR remain in their
previous state. Address output pins are Low. General-purpose output pins continue to output the
data in P2DR.
Figure 5-2 shows a schematic diagram of port 2.
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