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3.2.2
System Control Register (SYSCR)
7
—
0
R/W
6
—
0
—
5
INTM1
0
R/W
4
INTM0
0
R/W
3
NMIEG
0
R/W
0
RAME
1
R/W
2
MRESE
0
R/W
1
—
0
—
Bit
Initial value
R/W
:
SYSCR is an 8-bit readable/writable register that selects the interrupt control mode, the detected
edge for NMI, and enables or disables
MRES pin input and on-chip RAM.
SYSCR is initialized to H'01 by a power-on reset and in hardware standby mode. In a manual
reset, the INTM1, INTM0, NMIEG, and RAME bits are initialized, but the MRESE bit is not.
SYSCR is not initialized in software standby mode.
Bit 7—Reserved: Only 0 should be written to this bit.
Bit 6—Reserved: Read-only bit, always read as 0.
Bits 5 and 4—Interrupt Control Mode 1 and 0 (INTM1, INTM0): These bits select the control
mode of the interrupt controller. For details of the interrupt control modes, see section 5.4.1,
Interrupt Control Modes and Interrupt Operation.
Bit 5
Bit 4
Interrupt
INTM1
INTM0
Control Mode
Description
0
Control of interrupts by I bit
(Initial value)
1
—
Setting prohibited
1
0
2
Control of interrupts by I2 to I0 bits and IPR
1
—
Setting prohibited
Bit 3—NMI Edge Select (NMIEG): Selects the valid edge of the NMI interrupt input.
Bit 3
NMIEG
Description
0
An interrupt is requested at the falling edge of NMI input
(Initial value)
1
An interrupt is requested at the rising edge of NMI input