NEC PD78214 - Manual (Page 117)

88
µ
PD78214 Sub-Series
Fig. 5-37 Block Diagram of P67 (Port 6)
5.7.2 Setting the I/O Mode and Control Mode
The port 6 mode register (PM6) can put port 6 in either the input or output mode as shown in Fig. 5-38. Table 5-
8 lists the operations needed to make port 6 function as control pins.
P66 and P67 can always receive analog signals.
The ADM of the A/D converter specifies the mode of the A/D converter operation. (See Chapter 8.) To use port
6 as AN6 and AN7, however, it is necessary to specify the input mode using the port 6 mode register (PM6) and
disconnection of a pull-up resistor using the PUO6 bit (= 0) of the pull-up-resistor-option register (PUO).
For the
µPD78213, P64 and P65 function only as output pins for RD and WR, respectively.
Table 5-8 Port 6 Control Pin Functions and the Required Operations
P60
P61
P62
P63
P64
P65
P66
P67
Pin I/O Function
A16
A17
A18
A19
RD
WR
WAIT
REFRQ
Operation needed to make port 6 function as control pins
Output
Output
Output
Output
Output
Output
Input
Output
Set the MM6 bit of the MM register to 1.
For the µPD78213, no special operation is needed. For the other models, specify
the memory expansion mode by the MM2 through MM0 bits of the MM register.
Specify insertion of external wait using the PW register or the PWn1 and PWn0
bits (n = 2 or 3) of the MM register or by putting P66 in the input mode.
Set the RFEN bit of the RFM register to 1.
Internal bus
RD IN
RD OUT
A/D converter
P67
V DD
RD
PUO
WR PUO Pull-up resistor option register
PUO6
Port 6 mode register
PM67
WR PM67
Output latch
P67
WR
P67
Selector
Refresh signal
Refresh mode