100
Bits 1 and 0: Active (medium-speed) mode clock select (MA1, MA0)
Bits 1 and 0 choose ø
osc
/128, ø
osc
/64, ø
osc
/32, or ø
osc
/16 as the operating clock in active (medium-
speed) mode and sleep (medium-speed) mode. MA1 and MA0 should be written in active (high-
speed) mode or subactive mode.
Bit 1
MA1
Bit 0
MA0
Description
0
0
ø
osc
/16
0
1
ø
osc
/32
1
0
ø
osc
/64
1
1
ø
osc
/128
(initial value)
2. System control register 2 (SYSCR2)
Bit
Initial value
Read/Write
7
—
1
—
6
—
1
—
5
—
1
—
4
NESEL
1
R/W
3
DTON
0
R/W
0
SA0
0
R/W
2
MSON
0
R/W
1
SA1
0
R/W
SYSCR2 is an 8-bit read/write register for power-down mode control.
Bits 7 to 5: Reserved bits
These bits are reserved; they are always read as 1, and cannot be modified.
Bit 4: Noise elimination sampling frequency select (NESEL)
This bit selects the frequency at which the watch clock signal (ø
W
) generated by the subclock
pulse generator is sampled, in relation to the oscillator clock (ø
OSC
) generated by the system clock
pulse generator. When ø
OSC
= 2 to 16 MHz, clear NESEL to 0.
Bit 4
NESEL
Description
0
Sampling rate is ø
OSC
/16
1
Sampling rate is ø
OSC
/4
(initial value)