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CHAPTER 17 EXTENDED I/O SERIAL INTERFACE
17.1 Outline of Extended I/O Serial Interface
17.1
Outline of Extended I/O Serial Interface
The extended I/O serial interface is a serial I/O interface that can transfer data through
the adoption of 8-bit x 1 channel configured clock synchronization scheme. LSB first/
MSB first can be selected in data transfer.
■ Outline of Extended I/O Serial Interface
The following two operation modes are available for the extended I/O serial interface.
• Internal shift clock mode: Transfers data in sync with the internal clock.
• External shift clock mode: Transfers data in sync with the clock input through an external pin (SCK).
■ Block Diagram in Extended I/O Serial Interface
Figure 17.1-1 shows the block diagram of extended I/O serial interface.
(MSB first) D0 to D7
SIN
SOT
SCK
Internal clock
SMD2 SMD1 SMD0 SIE
368
In this mode, transfer operation performed by the CPU instruction is also
available by operating the general-use port sharing an external pin (SCK).
Figure 17.1-1 Block Diagram of Extended I/O Serial Interface
Internal data bus
SDR (Serial data register)
Control circuit
1
0
2
SIR BUSY STOP STRT MODE BDS SOE SCOE
Internal data bus
FUJITSU MICROELECTRONICS LIMITED
D7 to D0 (LSB first)
Transfer direction selection
Shift clock counter
Interrupt
request
#38
MB90335 Series
Initial value
Read
Write
SMCS
CM44-10137-6E
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