HD404654 Datasheet, PDF (67/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

SO₁
SCK₁
SI₁
Idle control
logic
I/O control
logic
Octal counter
(OC)
Clock
1/2
1/2
HD404654 Series
Serial interrupt
request flag
(IFS1)
Serial data
register
(SR1L/U)
Transfer
control
Selector
3
Serial mode register
1A (SM1A)
System ^øPER
clock
Prescaler S (PSS)
Serial mode register
1B (SM1B)
Figure 52 Block Diagram of Serial Interface 1
Serial Interface Operation
Selecting and Changing the Operating Mode: Table 24 lists the serial interfaces’ operating modes. To
select an operating mode, use one of these combinations of port mode register A (PMRA: $004), and serial
mode register 1A (SM1A: $005) settings; to change the operating mode of serial interface 1, always
initialize the serial interface internally by writing data to serial mode register 1A. Note that serial interface
1 is initialized by writing data to serial mode register 1A. Refer to the following section Registers for
Serial Interface for details.
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