UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 165

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

5.6 PORT 4
register (PM4). Each pin incorporates a software programmable pull-up resistor. This port has direct LED drive capability.
external memory or I/Os are extended.
5.6.1 Hardware Configuration
Port 4 is an 8-bit input/output port with an output latch. Input/output can be specified bit-wise by means of the port 4 mode
Port 4 also functions as the time division address/data bus (AD0 to AD7) by the memory extension mode register (MM) when
In the PD784021, this port only functions as the time division address/data bus (AD0 to AD7).
When RESET is input, port 4 is set as an input port (output high-impedance state), and the output latch contents are undefined.
The port 4 hardware configuration is shown in Figure 5-38.
Internal
Data
Bus
WR
WR
RD
WR
RD
Internal
Address
Bus
PUO
PM4n
P4n
PUO
P4n
Pull-Up Resistor Option Register
PUO4
Port 4 Mode Register
Output Latch
PM4n
P4n
Figure 5-38 Port 4 Block Diagram
CHAPTER 5 PORT FUNCTIONS
MM0-MM3
Input/
Output
Control
Circuit
V
DD
P4n
n = 0-7
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