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CHAPTER 6 PORT FUNCTIONS
6.3 Port Function Control Registers
The following four types of registers control the ports.
• Port mode registers (PM0 to PM3, PM5 to PM10, PM12, PM13)
• Pull-up resistor option register (PUOH, PUOL)
• Memory expansion mode register (MM)
• Key return mode register (KRM)
(1) Port mode registers (PM0 to PM3, PM5 to PM10, PM12, PM13)
These registers are used to set port input/output in 1-bit units.
PM0 to PM3, PM5 to PM10, PM12, and PM13 are independently set with a 1-bit or 8-bit memory manipulation
instruction
RESET input sets registers to FFH.
When port pins are used as alternate-function pins, set the port mode register and output latch according
to Table 6-6.
Cautions 1. Pins P00 and P07 are input-only pins.
2. As port 0 has an alternate function as external interrupt request input, when the port
function output mode 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.
3. The memory expansion mode register specifies P40 to P47 as input/output pins.