
CHAPTER 2 PIN FUNCTIONS
User’s Manual U12768EJ4V1UD
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(7) P60 to P65 (Port 6) 3-state I/O
P60 to P65 constitute a 6-bit I/O port that can be set to input or output in 1-bit units.
P60 to P65 can also function as an address bus (A16 to A21) when memory is expanded externally. When the
port 6 is accessed in 8-bit units, the higher 2 bits of port 6 are ignored when they are written to and 00 is read
when they are read.
The I/O signal level uses the bus interface power supply pins BVDD and BVSS as reference.
(a) Port function
P60 to P65 can be set to input or output in 1-bit units using the port 6 mode register (PM6).
(b) Alternate functions (External expansion function)
P60 to P65 can be set as A16 to A21 using the memory expansion mode register (MM).
(i)
A16 to A21 (Address 16 to 21) output
These comprise an address bus that is used for external access. These pins operate as the higher 6-bit
address output pins within a 22-bit address. The output changes in synchronization with the rising edge
of the clock in the T1 state of the bus cycle. When the timing sets the bus cycle to inactive, the previous
bus cycle’s address is retained.
(8) P70 to P77 (Port 7), P80 to P83 (Port 8) input
P70 to P77 constitute an 8-bit input-only port in which all the pins are fixed to input mode. P80 to P83 constitute a
4-bit input-only port in which all the pins are fixed to input.
P70 to P77 and P80 to P83 can also function as analog input pins for the A/D converter.
(a) Port function
P70 to P77 and P80 to P83 are input-only pins.
(b) Alternate functions
P70 to P77 also function as ANI0 to ANI7 and P80 to P83 also function as ANI8 to ANI11, but these alternate
functions are not switchable.
(i)
ANI0 to ANI11 (Analog input 0 to 11) input
These are analog input pins for the A/D converter.
Connect a capacitor between these pins and AVSS to prevent noise-related operation faults. Also, do
not apply voltage that is outside the range for AVSS and AVREF to pins that are being used as inputs for
the A/D converter. If it is possible for noise above the AVREF range or below the AVSS to enter, clamp
these pins using a diode that has a small VF value.