7477 datasheet(55/354 Pages) RENESAS

55 / 354 page

HARDWARE

1.10 I/O pins

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

1-38

(3) Pull-up control

When input has been selected by the Port direction register, pull-up control can be exerted in bit units

shown in Table 1.10.1 by the Port P0 pull-up control register (address 00D016) or the Port P1–P5

pull-up control register* (address 00D116). At this time, control is exerted by turning on and off the

pull-up transistor.

*: The Port P1–P4 pull-up control register is arranged in the 7470/7477 group.

Note: Ports other than P0 cannot be controlled in one-bit units. For example, when P10 is pulled up

at P1 (pull-up control in units of 4 bits), P11 to P13 are also pulled up.

Figure 1.10.3 shows a structure of Port P0 pull-up control register, and Figure 1.10.4 shows a

structure of Port P1–P5 pull-up control register.

Fig. 1.10.3 Structure of Port P0 pull-up control register

b7 b6 b5 b4 b3 b2 b1 b0

Name

Function

At reset RW

Port P0 pull-up control register

Port P00 pull-up

control bit

Port P01 pull-up

control bit

Port P02 pull-up

control bit

Port P03 pull-up

control bit

Port P04 pull-up

control bit

Port P05 pull-up

control bit

Port P06 pull-up

control bit

Port P07 pull-up

control bit

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

0 : No pull-up

1 : Pull-up

[Address 00D016]

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