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MB90335 Series
17.3
Operation of Extended I/O Serial Interface
Extended I/O interface consists of a serial mode control status register (SMCS) and a
serial data register (SDR) and is used to input and output 8-bit serial data.
Operation of extended I/O serial interface is described.
■ Outline of Operation of Extended I/O Serial Interface
When serial data is input or output, each of input and output operations is performed as described below.
●
Input of Serial data
The content of the serial data register is output in a bit serial fashion to the serial output pin (SOT pin) in
synchronization with the falling edge of the serial shift clock (external clock, internal clock).
●
Output of Serial data
Input from the serial input pin (SIN pin) into SDR (serial data register) in a bit serial fashion in
synchronization with the rising edge of the serial shift clock (external clock, internal clock).
The direction of shift (transfer from MSB or LSB) can be specified by the bit of direction specification
(BDS) of SMCS (serial mode control status register).
Once the transfer completes, the state goes into STOP or into data register R/W wait (or SDR R/W WAIT)
by MODE bit of the serial mode control status register (SMCS). To change state into TRANSFER from
each of the states, you should do each of the following steps.
• To return from HALT, write "0" in STOP bit, and "1" in STRT bit (STOP and STRT can be set
concurrently).
• To return from serial data register R/W wait (SDR R/W WAIT), read or write the data register.
CM44-10137-6E
FUJITSU MICROELECTRONICS LIMITED
CHAPTER 17 EXTENDED I/O SERIAL INTERFACE
17.3 Operation of Extended I/O Serial Interface
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