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
Abbreviation
SYSCR1
R/W
R/W
R/W
Initial Value
H'07
Address
H'FFF0
H'FFF1
System control register 1
System control register 2
SYSCR2
H'F0
1. System control register 1 (SYSCR1)
Bit
7
SSBY
0
6
STS2
0
5
STS1
0
4
STS0
0
3
2
—
1
1
0
LSON
0
MA1
1
MA0
1
Initial value
Read/Write
R/W
R/W
R/W
R/W
R/W
—
R/W
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
Description
SSBY
0
(initial value)
•
•
•
•
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
99
ETC [ ETC ]
