7702 datasheet(57/217 Pages) RENESAS

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7702/7703 Group User’s Manual

3–3

INPUT/OUTPUT PINS

3.1.1 Direction register

This register determines the input/output direction of the programmable I/O port. Each bit of this register

corresponds one for one to each pin of the microcomputer.

Figure 3.1.2 shows the structure of port Pi (i = 0 to 8) direction register.

3.1 Programmable I/O ports

Bit

Bit name

Functions

Port Pi0 direction bit

Port Pi2 direction bit

Port Pi3 direction bit

Port Pi4 direction bit

Port Pi6 direction bit

0 : Input mode

(Functions as an input port)

1 : Output mode

(Functions as an output port)

Port Pi5 direction bit

Port Pi direction register (i = 0 to 8)

(Addresses 416, 516, 816, 916, C16, D16, 1016, 1116, 1416)

Port Pi1 direction bit

Port Pi7 direction bit

At reset

Notes 1: Bits 7 to 4 of the port P3 direction register cannot be written (they may be either “0” or “1”) and are

fixed to “0” at reading.

2: In the memory expansion mode or the microprocessor mode, fix bits 0 and 1 of the port P4 direction

7703 Group

Fix the following bits which do not have the corresponding pin to “1”.

• Bit 3 of port P3 direction register

• Bits 3 to 6 of port P4 direction register

• Bits 0, 1, 6, and 7 of port P6 direction register

• Bits 3 to 6 of port P7 direction register

• Bits 4 and 5 of port P8 direction register

Bit

Corresponding

Pi7

Pi6

Pi5

Pi4

Pi3

Pi2

Pi1

Pi0

Fig. 3.1.2 Structure of port Pi (i = 0 to 8) direction register

7702 Datasheet(PDF) 57 Page - Renesas Technology Corp

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