CHAPTER 4 PORT FUNCTIONS
90
User’s Manual U11302EJ4V0UM
4.2.6 Port 8
Port 8 is an 8-bit output-only port. In mask ROM versions, use of pull-down resistors can be specified in 1-bit
units with the mask option. Pull-down resistor connection to V
LOAD
or V
SS
can be specified in 4-bit units. The
µ
PD78P0208 does not contain pull-down resistors.
Port 8 can drive LEDs directly.
Alternate functions include VFD controller/driver display output.
RESET input sets port 8 to output mode.
Figure 4-9 shows a block diagram of port 8.
Caution Adjust the number of pull-down resistors so that the total power dissipation (refer to 15.10
Calculating Total Power Dissipation) is not exceeded.
Figure 4-9. Block Diagram of P80 to P87
WR: Port 8 write signal
Internal bus
Output latch
(P80 to P87)
WR
PORT
Alternate function
Mask option
P80/FIP13
to
P87/FIP20
V
LOAD
P-ch open-drain
Only mask ROM versions.
The PD78P0208 has
no pull-down resistors.
µ
Содержание mPD780204
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