NEC 78K0 Series User Manual page 124

5.2.11 Port 14
Port 14 is a 6-bit I/O port with an output latch. Port 14 can be set to the input mode or output mode in 1-bit units
using port mode register 14 (PM14). When the P140 and P141 pins are used as an input port, use of an on-chip pull-
up resistor can be specified in 1-bit units by pull-up resistor option register 14 (PU14).
This port can also be used for external interrupt request input, buzzer output, clock output, serial interface data I/O,
clock I/O, busy input, and strobe output.
Reset signal generation sets port 14 to input mode.
Figures 5-25 shows a block diagram of port 14.
WR
PU
PU140, PU141
RD
WR
PORT
Output latch
(P140, P141)
WR
PM
PM140, PM141
P14: Port register 14
PU14: Pull-up resistor option register 14
PM14: Port mode register 14
RD: Read signal
WR××: Write signal
124
CHAPTER 5 PORT FUNCTIONS
Figure 5-25. Block Diagram of P140 and P141
PU14
Alternate
function
P14
PM14
Alternate
function
Preliminary User's Manual U17260EJ3V1UD
EV
DD
P-ch
P140/PCL/INTP6,
P141/BUZ/INTP7