Datasheet

CHAPTER 4 PORT FUNCTIONS
User’s Manual U18172EJ3V0UD
65
Figure 4-9. Block Diagram of P34 ( μ PD78F920x)
RD
P34/RESET
Option
byte
Reset
Internal bus
RD: Read signal
Caution Because the P34 pin functions alternately as the RESET pin, if it is used as an input port pin, the
function to input an external reset signal to the RESET pin cannot be used. The function of the
port is selected by the option byte. For details, refer to CHAPTER 15 OPTION BYTE.
Also, since the option byte is referenced after the reset release, if low level is input to the RESET
pin before the referencing, then the reset state is not released. When it is used as an input port
pin, connect the pull-up resistor.
Figure 4-10. Block Diagram of P34 (
μ PD78F950x)
RD
P34/RESET
Reset
WR PU
PU34
PU3
P-ch
Internal bus
Option byte
V
DD
RD: Read signal
Caution Because the P34 pin functions alternately as the RESET pin, if it is used as an input port pin, the
function to input an external reset signal to the RESET pin cannot be used. The function of the
port is selected by the option byte. For details, refer to CHAPTER 15 OPTION BYTE.
Also, since the option byte is referenced after the reset release, if low level is input to the RESET
pin before the referencing, then the reset state is not released. When it is used as an input port
pin, connect an on-chip pull-up resistor by using bit 4 (PU34) of pull-up resistor option register 3
(PU3).
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