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2.4 CAUTIONS
(1) When connecting unused pins, if the input/output mode is undefined for an input/output alternate-function pin, it should be
connected to V
with a resistor of several tens of kΩ (especially when the reset input pin becomes the low-level input
DD0
voltage or over upon powering on, and when input/output is switched by software.)
(2) P60 to P63 of the µ PD784031 are in the output high-impedance state while the RESET signal is input, but output a low level
after the RESET signal has been cleared. Therefore, design the external circuit so that the low level may be output as the
initial status.
(3) In the µ PD78233 and 78237, the TEST pin is the MODE pin and is fixed high. When changing over from the µ PD78233/
78237, the circuitry must be modified so that this pin is directly connected to V
Modification as shown below is needed if the µ PD78234/78238 was used with switching between the on-chip ROM mode
and ROM-less mode performed by MODE pin switching (the TEST pin must be directly connected to V
Modifications examples:
•
Incorporate all programs in ROM
•
Store all programs in external ROM
•
Change the location address of a program previously held in external ROM, shift the address to avoid overlapping on-
chip ROM, and execute this program from the program in on-chip ROM
CHAPTER 2 PIN FUNCTIONS
User's Manual U11316EJ4V1UD
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SS0
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SS0
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