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CHAPTER 2 PIN FUNCTIONS
(8) P70 to P77 (Port 7) ... input
Port 7 is an 8-bit input-only port whose pins are all fixed to input.
P70 to P77 function as input ports, as well as A/D converter analog inputs in the control mode. However, the
input port and analog input pin cannot be switched.
(a) Port mode
P70 to P77 are dedicated input ports.
(b) Control mode
P70 to P77 also function as AN10 to AN17 pins and cannot be switched.
(i)
ANI0 to ANI7 (Analog Input) ... input
These pins are analog input pins to A/D converter.
To prevent malfunction due to noise, connect a capacitor between these pins and AV
SS
.
Make sure that voltage other than the range of AV
SS
and AV
REF
is not applied to the input pin used
for A/D converter input. If there is the possibility that noise whose voltage is AV
REF
or more or noise
whose voltage is AV
SS
or less may be generated, clamp the voltage using a diode with small V
F
.
(9) P90 to P96 (Port 9) ... 3-state I/O
These pins constitute a 7-bit I/O port, port 9, and are also used to output control signals.
P90 to P96 function not only as I/O port pins, but also as control signal output pins and bus hold control signal
input/output pins when an external memory is used in the control mode (external expansion mode).
If port 9 is accessed in 8-bit units, the higher 1-bit is ignored if the access is write, and undefined if the access
is read.
This port can be set in the port or control mode in 1-bit units by using mode specification pin (MODE) and
memory expansion mode register (MM).
(a) Port mode
P90 to P96 can be set in the input or output port mode in 1-bit units by using port 9 mode register (PM9).
(b) Control mode (External Expansion Mode)
P90 to P96 can be used to output control signals when so specified by the MODE pin and MM register
when an external memory is used.
(i)
LBEN (Lower Byte Enable) ... output
This is the lower byte enable signal of the 16-bit external data bus.
This signal changes in synchronization with the rising edge of the clock in the T1 state of the bus
cycle. The status of the bus signal remains unchanged in the idle state (TI).
(ii)
UBEN (Upper Byte Enable) ... output
This is the upper byte enable signal of the 16-bit external data bus. It becomes inactive (high) during
byte access to an even address and becomes active (low) during byte access to an odd address.
This signal changes in synchronization with the rising of the clock in the T1 state of the bus cycle.
The status of the bus signal remains unchanged in the idle state (TI).
Access
UBEN
LBEN
A0
Word Access
0
0
0
Half-word Access
0
0
0
Byte Access
Even address
1
0
0
Odd address
0
1
1