Outline Of Serial I/O - Fujitsu MB90390 Series Hardware Manual

CHAPTER 22 SERIAL I/O
22.1

Outline of Serial I/O

The serial I/O interface operates in two modes:
• Internal shift clock mode: Data is transferred in synchronization with the internal
• External shift clock mode: Data is transferred in synchronization with the clock
■ Serial I/O Block Diagram
This block is a serial I/O interface that allows data transfer using clock synchronization. The interface
consists of a single eight-bit channel. Data can be transferred from the LSB first or MSB first.
(MSB first) D7 to D0
SIN3
SIN4
SOT4
SOT3
SCK3
SCK4
Internal clock
438
clock.
supplied via the external pin (SCK4). By manipulating the
general-purpose port sharing the external pin (SCK4), data
can also be transferred by a CPU instruction in this mode.
Figure 22.1-1 Extended Serial I/O Interface Block Diagram
SDR (Serial data register)
2 1 0
SMD2 SMD1 SMD0 SIE
Internal data bus
D7 to D0 (LSB first)
Transfer direction selection
Control circuit
SIR BUSY STOP STRT MODE
Interrupt
request
Internal data bus
Read
Write
Shift clock counter
BDS SOE SCOE