uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
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CHAPTER 4 PORT FUNCTIONS<br />
4.2.4 Port 8<br />
This is an 8-bit P-ch open-drain I/O port with output latches. For mask ROM versions, use of a pull-down resistor<br />
for VLOAD can be specified by a mask option.<br />
RESET input sets port 8 to input mode.<br />
Figures 4-7 and 4-8 show block diagrams of port 8.<br />
Internal bus<br />
Internal bus<br />
WRPORT<br />
RDPORT<br />
PM: Port mode register<br />
RD: Port 8 read signal<br />
WR: Port 8 write signal<br />
WRPORT<br />
RDPORT<br />
PM: Port mode register<br />
RD: Port 8 read signal<br />
WR: Port 8 write signal<br />
Figure 4-7. Block Diagram of P80 to P87 (µPD789870, 789871)<br />
Output latch<br />
(P80 to P87)<br />
Alternate<br />
function<br />
Output latch<br />
(P80 to P87)<br />
Alternate<br />
function<br />
Mask option<br />
switch<br />
Figure 4-8. Block Diagram of P80 to P87 (µPD78F9872)<br />
P-ch<br />
P80/FIP24 to<br />
P87/FIP17<br />
Preliminary User’s Manual U14938EJ1V0UM 61<br />
VDD1<br />
VDD1<br />
P-ch<br />
P-ch<br />
VLOAD<br />
P80/FIP24 to<br />
P87/FIP17
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