• Use byte access to access the ports.
When ports 0 to A (excluding bit 3 of port 9) are being used as external bus pins, the external bus
functions have priority. Therefore, when the ports operate as external bus pins, I/O switching will
not occur even though the DDR register is rewritten. The value of the DDR register is valid when
the PFR register is switched and the pins are used as general-purpose pins.
• In stop mode (HIZ = 0), the setting of the pull-up resistor control register has priority.
• In stop mode (HIZ = 1), the setting of the pull-up resistor control register is disabled.
• When a pin is being used as an external bus pin, use of a pull-up resistor is not allowed. Set so
that "1" is not written to the relevant bit of the pull-up control register (PCR).
• When the registers are used in single-chip mode, the external bus functions of PFR6, 8, 9, A, B1,
B2, and C cannot be used. Do not rewrite these registers. In addition, in single-chip mode,
external bus function output is disabled for the functions (A23 to A16, WR1, SYSCLK, and CS3 to
CS0) that result from the initial values set to "1" in PFR6, 8, 9, and A. (Use these registers as