Port 14 - NEC 78K0 User Manual

4.2.11 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 to P145 pins are used as an input port, use of an on-chip pull-up
resistor can be specified by pull-up resistor option register 14 (PU14).
This port can also be used for external interrupt request input, serial interface data I/O, clock I/O, busy input,
buzzer output, and clock output.
RESET input sets port 14 to input mode.
Figures 4-22 to 4-25 show block diagrams of port 14.
WR
PU
PU140, PU141
Alternate
function
RD
WR
PORT
Output latch
(P140, P141)
WR
PM
PM140, PM141
Alternate
function
PU14: Pull-up resistor option register 14
PM14: Port mode register 14
RD: Read signal
WR××: Write signal
CHAPTER 4 PORT FUNCTIONS
Figure 4-22. Block Diagram of P140 and P141
PU14
PM14
User's Manual U15947EJ2V0UD
*
EV
DD
P-ch
P140/PCL/INTP6,
P141/BUZ/BUSY0/INTP7
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