UPD784938 Datasheet, PDF (119/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.2 Port 0
Port 0 is an 8-bit input/output port with an output latch, and has direct transistor drive capability. Input/output can be specified
in 1-bit units by means of the port 0 mode register (PM0). Each pin incorporates a software programmable pull-up resistor.
P00 to P03 and P04 to P07 can output the buffer register (P0L, P0H) contents at any time interval as 4-bit real-time output
ports or one 8-bit real-time output port. The real-time output port control register (RTPC) is used to select whether this port is
used as a normal output port or a real-time output port.
When RESET is input, port 0 is set as an input port (output high-impedance state), and the output latch contents are undefined.
6.2.1 Hardware configuration
The port 0 hardware configuration is shown in Figure 6-2.
Figure 6-2. Port 0 Block Diagram
VDD
WRPUOL ^{Pull-up resistor option register L}
RDPUOL
PUOL0
Internal
bus
WRRTPC
RDRTPC
Real-time output port control register
P0LM
(P0HM)
WRPM0
RDPM0
Port 0 mode register
PM0n
(PM0m)
WRP0L
RDP0L
WROUT
RDP0
Buffer register
P0Ln
(P0Hm)
Trigger
Selector
Output latch
P0n
(P0m)
P0n
(P0m)
n=0,1,2,3
m=4,5,6,7
Preliminary User’s Manual U13987EJ1V0UM00
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