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CHAPTER 16 SERIAL INTERFACE CHANNEL 0 (
m
PD78064Y Subseries)
16.4.2 3-wire serial I/O mode operation
The 3-wire serial I/O mode is valid for connection of peripheral I/O units and display controllers which incorporate
a conventional synchronous clocked serial interface as is the case with the 75X, 78K, and 17K series.
Communication is carried out with three lines of serial clock (SCK0), serial output (SO0), and serial input (SI0).
(1) Register setting
The 3-wire serial I/O mode is set with the serial operating mode register 0 (CSIM0) and serial bus interface
control register (SBIC).
(a) Serial operating mode register 0 (CSIM0)
CSIM0 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM0 to 00H.
The shaded area is used in the 3-wire serial I/O mode.
Notes 1.
Bit 6 (COI) is a read-only bit.
2.
Can be used as P25 (CMOS input/output) when used only for transmission.
3.
Be sure to set WUP to 0 when the 3-wire serial I/O mode is selected.
Remark
¥
: don’t care
6
5
4
3
2
1
0
7
Symbol
CSIM0
CSIE0
COI
WUP
CSIM04 CSIM03 CSIM02 CSIM01 CSIM00
CSIM01
0
1
Serial Interface Channel 0 Clock Selection
Input Clock to SCK0 pin from off-chip
8-bit timer register 2 (TM2) output
0
2-wire serial I/O mode (See section 16.4.3, “2-wire serial I/O mode operation”.)
or
R/W
1
Clock specified with bits 0 to 3 of timer clock select register 3 (TCL3)
CSIM
04
0
CSIM00
×
0
1
FF60H 00H R/W
Note 1
Address After Reset R/W
R/W
CSIM
03
CSIM
02
PM25 P25 PM26 P26 PM27 P27
Operation
Mode
Start Bit
SIO/SB0/SDA0
/P25 Pin Function
SO0/SB1/SDA1
/P26 Pin Function
SCK0/SCL/P27
Pin Function
×
1
1
WUP
0
1
Wake-up Function Control
Interrupt request signal generation with each serial transfer in any mode
Interrupt request signal generation when the address received after detecting start condition
(when CMDD=1) matches the slave address register data in I
2
C bus mode
R/W
1
MSB
LSB
1
×
0
0
0
1
Note 2
3-wire serial
l/O mode
SI0
(Input)
SO0
(CMOS output)
SCK0 (CMOS
input/output)
I
2
C bus mode (See section 16.4.4, “I
2
C bus mode operation”.)
Note 2
Note 3
Note 2
CSIE0
0
Serial Interface Channel 0 Operation Control
Operation stopped
Operation enabled
R/W
1