Renesas PCA7401 Bedienungsanleitung PDF herunterladen (Seite 31)

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER

and ON-SCREEN DISPLAY CONTROLLER

M37281MAH–XXXSP,M37281MFH–XXXSP

M37281MKH–XXXSP,M37281EKSP

MITSUBISHI MICROCOMPUTERS

Rev. 1.0

8.5 SERIAL I/O

This microcomputer has a built-in serial I/O which can either transmit

or receive 8-bit data serially in the clock synchronous mode.

The serial I/O block diagram is shown in Figure 8.5.1. The synchro-

nous clock I/O pin (SCLK), and data output pin (SOUT) also function

as port P4, data input pin (SIN) also functions as ports P1 and P7.

Bit 2 of the serial I/O mode register (address 021316) selects whether

the synchronous clock is supplied internally or externally (from the

SCLK pin). When an internal clock is selected, bits 1 and 0 select

whether f(XIN) or f(XCIN) is divided by 8, 16, 32, or 64. To use the

pin for servial I/O, set the bit corresponding to SCLK pin of thr port

P4 direction register (address 00C916) and the bit corresponding

to SIN pin of the port P1 direction register (address 00C316) to “0”.

Fig. 8.5.1 Serial I/O Block Diagram

Serial I/O shift register (8)

Data bus

Serial I/O

interrupt request

Selection

ate: Connect to

black side at

reset.

Synchronous

circuit

Frequency divider

1/81/4 1/16

SM1

SM0

Serial I/O counter (8)

SM5 : LSB

MSB

SM2

1/2

OUT

CLK

1/2

(Address 0214

)

CIN

1/2

CM7

1/2

Note : When the data is set in the serial I/O register (address 0214

), the register functions as the serial I/O shift register.

(Note)

CM : CPU mode register

SM : Serial I/O mode register

More over, set the bit corresponding to SOUT of rhe port P4 direction

set the corresponding bits of the port P4 direction register (address

00C916) to “1.”

The operation of the serial I/O is described below. The operation of

the serial I/O differs depending on the clock source; external clock or

internal clock.

1 2 ... 26 27 28 29 30 31 32 33 34 35 36 ... 158 159

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