MB90480/485 Series
3. Expanded I/O Serial Interface
The expanded I/O serial interface is an 8-bit × 1-channel serial I/O interface for clock synchronized data
transfer. A selection of LSB-first or MSB-first data transfer is provided.
There are two serial I/O operation modes.
• Internal shift clock mode : Data transfer is synchronized with the internal clock signal.
• External shift clock mode : Data transfer is synchronized with a clock signal input from the external clock
signal pin (SCK) . In this mode the general-purpose port that shares the external
clock signal pin (SCK) can be used for transfer according to CPU instructions.
(1) Register List
Serial mode control status register 0/1 (SMCS0, SMCS1)
Initial value
15
14
13
12
11
10
9
8
Address : 000027H
00002BH
00000010B
SMD2 SMD1 SMD0
SIE
SIR
BUSY STOP
STRT
R/W
R/W
R/W
R/W
R/W
R
R/W
R/W
7
6
5
4
3
2
1
0
Address : 000026H
00002AH
----0000B
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
MODE
BDS
SOE
SCOE
R/W
R/W
R/W
R/W
Serial data register 0/1 (SDR0, SDR1)
7
6
5
4
3
2
1
0
Address : 000028H
00002CH
XXXXXXXXB
0---0000B
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Communication prescaler control register 0/1 (SDCR0, SDCR1)
15
14
13
12
11
10
9
8
Address : 000029H
00002DH
MD
⎯
⎯
⎯
DIV3
DIV2
DIV1
DIV0
R/W
⎯
⎯
⎯
R/W
R/W
R/W
R/W
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