System Control Registers - Hitachi H8/3937 Series Hardware Manual

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 Description
SSBY
•
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 Initial Value
R/W H'07
R/W H'F0
4 3
STS0 LSON
0 0
R/W R/W
Address
H'FFF0
H'FFF1
2 1 0
— MA1 MA0
1 1 1
— R/W R/W
(initial value)