Samsung KS57C2308 Manual page 178

OSCILLATOR CIRCUITS
Mode Condition
Main Main oscillator runs.
Oscillation Sub oscillator runs
STOP Mode (stops).
System clock is the
main oscillation clock.
Main oscillator runs.
Sub oscillator runs.
System clock is the
sub oscillation clock.
Sub Main oscillator runs.
oscillation Sub oscillator runs.
STOP Mode System clock is the
main oscillation clock.
Main oscillator runs
(stops).
Sub oscillator runs.
System clock is the
sub oscillation clock.
NOTES:
1. This mode must not be used.
2. Oscillation stabilization time by interrupt is 1 / (256 x BT clocks). Oscillation stabilization time by a reset is 31.3 ms at
4.19 MHz, main oscillation clock.
6-8
Table 6-4. Main/Sub Oscillation Stop Mode
Method to issue Osc Stop
STOP instruction:
Main oscillator stops.
CPU is in idle mode.
Sub oscillator still runs
(stops).
Set SCMOD.3 to "1"
Main oscillator stops, halting
the CPU operation.
Sub oscillator still runs
(stops).
STOP instruction:
Main oscillator stops.
CPU is in idle mode.
Sub oscillator still runs.
Set SCMOD.3 to "1"
Main oscillator stops.
CPU still operates.
Sub oscillator still runs.
Set SCMOD.2 to "1"
Main oscillator still runs.
CPU operates.
Sub oscillator stops.
Set SCMOD.2 to "1"
Main oscillator still runs
(stops).
Sub oscillator stops, halting
the CPU operation.
Osc Stop Release Source
Interrupt and reset:
After releasing stop mode, main
oscillation starts and oscillation
stabilization time is elapsed. And then
the CPU operates.
Oscillation stabilization time is
1 / {256 x BT clock (fx)}.
(1)
Reset:
Interrupt can't start the main oscillation.
Therefore, the CPU operation can never
be restarted.
(1)
BToverflow and reset:
After the overflow of basic timer [1 /
{256 x BT clock (fxt)}], CPU operation
and main oscillation automatically start.
Set SCMOD.3 to "0" or reset
Set SCMOD.2 to "0" or reset
Reset
KS57C2308/P2308/C2316/P2316
(2)