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2.4 Serial I/O
2-41
4513/4514 Group User’s Manual
2.4.2 Related registers
(1) Serial I/O register SI
Serial I/O register SI is the 8-bit data transfer serial/parallel conversion register. Data can be set to
register SI through registers A and B with the TSIAB instruction.
(2) Serial I/O mode register J1
Serial I/O synchronous clock selection bit is assigned to bit 0, serial I/O port selection bit is assigned
to bit 1 and serial I/O internal clock dividing ratio selection bit is assigned to bit 2.
Set the contents of this register through register A with the TJ1A instruction. The TAJ1 instruction
can be used to transfer the contents of register J1 to register A.
Table 2.4.1 shows the serial I/O mode register J1.
Table 2.4.1 Serial I/O mode register J1
Note: “R” represents read enabled, and “W” represents write enabled.
(3) Serial I/O transmission/reception completion flag (SIOF)
Serial I/O transmission/reception completion flag (SIOF) is set to “1” when serial data transmission
or reception completes. The state of SIOF flag can be examined with the skip instruction (SNZSI).
Serial I/O mode register J1 at reset : 00002 at RAM back-up : state retained
R/W
This bit has no function, but read/write is enabled.
Instruction clock signal divided by 8
Instruction clock signal divided by 4
Input ports P20, P21, P22 selected
Serial I/O ports S
CK
, S
OUT
, S
IN
/input ports P2
0
, P2
1
, P2
2
selected
External clock
Internal clock (instruction clock divided by 4 or 8)
Not used
Serial I/O internal clock dividing
ratio selection bit
Serial I/O port selection bit
Serial I/O synchronous clock
selection bit
J13
J12
J11
J10
0
1
0
1
0
1
0
1