M37280MF Datasheet, PDF (30/178 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER

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MITSUBISHI MICROCOMPUTERS
M37280MF–XXXSP, M37280MK–XXXSP
M37280EKSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
12.5 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 12.5.1. 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 SOUT
and SCLK pins for serial I/O, set the corresponding bits of the port P4
direction register (address 00C916) to “0.” To use SIN pin for serial
I/O, set the corresponding bit of the port P1 direction register (ad-
dress 00C316) to “0.”
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.
XCIN
XIN
SCLK
SOUT
SIN
1/2
1/2
1/2
CM7
Synchronous
circuit
Data bus
SM2
Frequency divider
1/2 1/4 1/8 1/16
SM1
SM0
Serial I/O counter (8)
Selection gate: Connect to
black side at
reset.
CM : CPU mode register
SM : Serial I/O mode register
Serial I/O
interrupt request
SM5 : LSB
MSB
(Note)
Serial I/O shift register (8)
8 ^{(Address 021416)}
Note : When the data is set in the serial I/O register (address 021416), the register functions as the serial I/O shift register.
Fig. 12.5.1 Serial I/O Block Diagram
Rev. 1.0
30