Renesas PROM Programming Adapter PCA7435FPG02 Uživatelský manuál stáhnout pdf (Strana 16)

7540 Group

Rev.4.00 Jun 21, 2004 page 16 of 82

REJ03B0011-0400Z

I/O Ports

[Direction registers] PiD

The I/O ports have direction registers which determine the input/

output direction of each pin. Each bit in a direction register corre-

sponds to one pin, and each pin can be set to be input or output.

When “1” is set to the bit corresponding to a pin, this pin becomes

an output port. When “0” is set to the bit, the pin becomes an in-

put port.

When data is read from a pin set to output, not the value of the pin

itself but the value of port latch is read. Pins set to input are float-

ing, and permit reading pin values.

If a pin set to input is written to, only the port latch is written to and

the pin remains floating.

[Pull-up control register] PULL

By setting the pull-up control register (address 001616), ports P0

and P3 can exert pull-up control by program. However, pins set to

output are disconnected from this control and cannot exert pull-up

control.

Note: P26/AN6, P27/AN7, P35 and P36 do not exist for the 32-pin

version.

Accordingly, the following settings are required;

. Set direction registers of ports P26 and P27 to output.

. Set direction registers of ports P35 and P36 to output.

[Port P1P3 control register] P1P3C

By setting the port P1P3 control register (address 001716), a

CMOS input level or a TTL input level can be selected for ports

P10, P12, P13, P36, and P37 by program.

Fig. 16 Structure of port P1P3 control register

Fig. 15 Structure of pull-up control register

Port P1P3 control register

(P1P3C: address 0017

, initial value: 00

)

b7 b0

P37/INT0 input level selection bit

0 : CMOS level

1 : TTL level

6/INT1 input level selection bit

0 : CMOS level

1 : TTL level

0,P12,P13 input level selection bit

0 : CMOS level

1 : TTL level

Not used

Note: Keep setting the P3

/INT

input level selection bit

to “0” (initial value) for 32-pin version.

Pull-up control register

(PULL: address 0016

, initial value: 00

)

pull-up control bit

b7 b0

0 : Pull-up Off

1 : Pull-up On

Note : Pins set to out

orts are disconnected from

ull-u

control.

pull-up control bit

, P3

pull-up control bit

– P3

pull-up control bit

– P0

pull-up control bit

, P0

pull-up control bit

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 87 88

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