Port 6 - NEC 78K0 User Manual

4.2.7

Port 6

Port 6 is an 8-bit I/O port with an output latch. Port 6 can be set to the input mode or output mode in 1-bit units
using port mode register 6 (PM6).
This port has the following functions for pull-up resistors. These functions differ depending on the higher 4
bits/lower 4 bits of the port, and whether the product is a mask ROM version or a flash memory version.
Mask ROM version
Flash memory version
PU6: Pull-up resistor option register 6
The P60 to P63 pins are N-ch open-drain pins.
The P64 to P67 pins can also be used for the control signal output function in external memory expansion mode.
RESET input sets port 6 to input mode.
Figures 4-16 to 4-18 show block diagrams of port 6.
Caution P66 can be used as an I/O port when an external wait is not used in external memory expansion
mode.
RD
WR
PORT
WR
PM
PM6: Port mode register 6
RD: Read signal
WR××: Write signal
CHAPTER 4 PORT FUNCTIONS
Table 4-4. Pull-up Resistor of Port 6
Higher 4 Bits (Pins P64 to P67)
An on-chip pull-up resistor can be
connected in 1-bit units by PU6
Figure 4-16. Block Diagram of P60 to P63
Output latch
(P60 to P63)
PM6
PM60 to PM63
User's Manual U15947EJ2V0UD
Lower 4 Bits (Pins P60 to P63)
An on-chip pull-up resistor can be
specified in 1-bit units by mask option
On-chip pull-up resistors are not provided
*
Selector
EV
DD
Mask option resistor

Mask ROM versions only


No pull-up resistor for

flash memory versions

P60 to P63





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