7477 datasheet(64/354 Pages) RENESAS

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7470/7471/7477/7478 GROUP USER’S MANUAL

HARDWARE

1.10 I/O pins

1-47

Port

P10 to P13

P15, P17

P2 (7470/7471 group)

P14, P16

P2 (7477/7478 group)

P30 to P33

(Note 7)

VREF

AVSS

Terminations

(Note 1)

(Note 3)

(Note 1)

Pull down (connect to

VSS) ports through a

resistor (Note 2)

(Note 5)

(Note 6)

(Note 8)

Connect

VCC

(Note 6)

(4) Termination of unused pins

Table 1.10.2 shows a termination of unused pins.

Table 1.10.2 Termination of unused pins

Notes 1: A pin that can be opened at the unused time has a circuit that does not allow a current to flow

into itself unless any read signal is internally input even if a medium-level input is applied at the

open state.

2: For programmable I/O ports, do not connect two or more ports together through a resistor to VCC

or VSS.

3: Note the following when setting them to the output mode and making the pins open.

• The ports function as input ports in the period from reset release till switching the ports to the

output mode by software. Accordingly, the power source current may be increased depending

on the input levels of the pins.

• If the Port direction register has been changed into the input mode by runaway or noise, re-set

the Port direction register to the output mode periodically by software.

4: To pull up a pin, set the Port direction register and the Port latch so that this pin may be into the

input mode or “H” output state.

5: To pull down a pin, set the Port direction register, the Port pull-up control register and the Port

latch so that this pin may be put in the no pull-up transistor state in the input mode or in the “L”

output state.

6: These pins are connect to the VCC or VSS without a resistor when the wiring is the shortest.

However, they are connect to the VCC or VSS through a resistor. In addition, the P33 pin of the

built-in programmable ROM version is used in common with the VPP pin, insert a resistor of about

5 k in series and connect by the shortest wiring.

7: When using neither the P50 pin nor the P51 pin (used in common with the XCIN and XCOUT pin),

set bit 4 of the CPU mode register to “0” (P50 and P51 functions).

8: To pull down a pin, set the port pull-up control register so that a pull-up transistor will not be

provided for this pin.

Pull-up (connect to VCC)

ports through a resistor

(Note 2)

(Note 4)

(Note 6)

Connect

VSS

(Note 6)

Open

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