Port 0; Hardware Configuration - NEC uPD784038 Series User Manual

5.2 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
bit-wise 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.

5.2.1 Hardware Configuration

The port 0 hardware configuration is shown in Figure 5-2.
WR
PUO
WR
RTPC
WR
RTPC
WR
PM0
RD
PM0
WR
P0L
Internal
Bus
RD
P0L
WR
OUT
RD
P0
CHAPTER 5 PORT FUNCTIONS
Figure 5-2 Port 0 Block Diagram
Pull-Up Resistor Option Register
PUO0
Real-Time Output Port Control Register
P0ML
(P0MH)
Port 0 Mode Register
PM0n
(PM0m)
Trigger
Buffer Register
P0Ln
(P0Hm)
User's Manual U11316EJ4V1UD
Output Latch
P0n
Selector
(P0m)
V
DD0
P0n
(P0m)
n = 0, 1, 2, 3
m = 4, 5, 6, 7
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