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
R/W
Initial Value
Address
System control register 1
SYSCR1
R/W
H'07
H'FFF0
System control register 2
SYSCR2
R/W
H'F0
H'FFF1
1.
System control register 1 (SYSCR1)
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
(initial value)
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
Bit
Initial value
Read/Write
7
SSBY
0
R/W
6
STS2
0
R/W
5
STS1
0
R/W
4
STS0
0
R/W
3
LSON
0
R/W
0
MA0
1
R/W
2
—
1
—
1
MA1
1
R/W
98