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5.1.1
System Control Registers
The operation mode is selected using the system control registers described in table 5.3.
Table 5.3
System Control Registers
Name
System control register 1
System control register 2
1. System control register 1 (SYSCR1)
Bit
SSBY
Initial value
Read/Write
R/W
SYSCR1 is an 8-bit read/write register for control of the power-down modes.
Upon reset, SYSCR1 is initialized to H'07.
Bit 7: Software standby (SSBY)
This bit designates transition to standby mode or watch mode.
Bit 7
SSBY
Description
•
0
When a SLEEP instruction is executed in active mode,
a transition is made to sleep mode
•
When a SLEEP instruction is executed in subactive mode, a transition is made to
subsleep mode
•
1
When a SLEEP instruction is executed in active mode, a transition is made to
standby mode or watch mode
•
When a SLEEP instruction is executed in subactive mode, a transition is made to
watch mode
98
Abbreviation
SYSCR1
SYSCR2
7
6
5
STS2
STS1
0
0
0
R/W
R/W
R/W
R/W
R/W
4
3
STS0
LSON
0
0
R/W
R/W
Initial Value
Address
H'07
H'FFF0
H'F0
H'FFF1
2
1
0
—
MA1
MA0
1
1
1
—
R/W
R/W
(initial value)
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