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6.3 Port Function Control Registers
The following four types of registers control the ports.
• Port mode registers (PM0, PM1, PM2, PM3, PM5, PM6)
• Pull-up resistor option register (PUO)
• Memory expansion mode register (MM)
• Key return mode register (KRM)
(1) Port mode registers (PM0, PM1, PM2, PM3, PM5, PM6)
These registers are used to set port input/output bit-wise.
PM0, PM1, PM2, PM3, PM5, and PM6 are independently set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PM0 to 1FH and other registers to FFH.
When a port pin is used as its alternate function pin, set the port mode register and the output latch according
to Table 6-5.
Cautions 1. P00 and P04 pins are input-only pins.
2. Input/output of P40 to P47 pins are specifiable with a memory expansion mode register (MM).
3. As port 0 is also used for external interrupt request input, when the port function output mode
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CHAPTER 6 PORT FUNCTIONS
is specified and the output level is changed, the interrupt request flag is set. When the output
mode is used, therefore, the interrupt mask flag should be set to 1 beforehand.
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