CHAPTER 4 PORT FUNCTIONS
89
User’s Manual U11302EJ4V0UM
4.2.5 Port 7
Port 7 is a 5-bit I/O port with an output latch. The P70 to P74 pins can be set to input mode/output mode in 1-
bit units using port mode register 7 (PM7). In mask ROM versions, use of pull-up resistors can be specified in 1-
bit units with the mask option. The
µ
PD78P0208 does not contain pull-up resistors.
Port 7 can drive LEDs directly.
RESET input sets port 7 to input mode.
Figure 4-8 shows a block diagram of port 7.
Caution The low-level input leak current flowing to the P70 to P74 pins varies depending on the following
conditions.
[For mask ROM version]
• When a pull-up resistor is connected:
• –3
µ
A (max.) regardless of operational conditions
• When a pull-up resistor is not connected:
• –200
µ
A (max.) during 1.5 clock cycles after read instruction execution to port 7 (P7)
or port mode register 7 (PM7)
• –3
µ
A (max.) under other conditions
[For PROM version]
• –200
µ
A (max.) during 1.5 clock cycles after read instruction execution to port 7 (P7)
or port mode register 7 (PM7)
• –3
µ
A (max.) under other conditions
Figure 4-8. Block Diagram of P70 to P74
PM: Port mode register
RD: Port 7 read signal
WR: Port 7 write signal
Internal bus
Output latch
(P70 to P74)
WR
PORT
PM70 to PM74
WR
PM
Selector
RD
V
DD
Only mask ROM
versions. The
PD78P0208 has
no pull-up resistors.
Mask option
P70 to P74
µ