Samsung KS57C2308 - page 178

OSCILLATOR CIRCUITS KS57C2308/P2308/C2316/P2316
6-8
Table 6-4. Main/Sub Oscillation Stop Mode
Mode Condition Method to issue Osc Stop Osc Stop Release Source (2)
Main
Oscillation
STOP Mode
Main oscillator runs.
Sub oscillator runs
(stops).
System clock is the
main oscillation clock.
STOP instruction:
Main oscillator stops.
CPU is in idle mode.
Sub oscillator still runs
(stops).
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)}.
Set SCMOD.3 to “1” (1)
Main oscillator stops, halting
the CPU operation.
Sub oscillator still runs
(stops).
Reset:
Interrupt can’t start the main oscillation.
Therefore, the CPU operation can never
be restarted.
Main oscillator runs.
Sub oscillator runs.
System clock is the
sub oscillation clock.
STOP instruction: (1)
Main oscillator stops.
CPU is in idle mode.
Sub oscillator still runs.
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 “1”
Main oscillator stops.
CPU still operates.
Sub oscillator still runs.
Set SCMOD.3 to “0” or reset
Sub
oscillation
STOP Mode
Main oscillator runs.
Sub oscillator runs.
System clock is the
main oscillation clock.
Set SCMOD.2 to “1”
Main oscillator still runs.
CPU operates.
Sub oscillator stops.
Set SCMOD.2 to “0” or reset
Main oscillator runs
(stops).
Sub oscillator runs.
System clock is the
sub oscillation clock.
Set SCMOD.2 to “1”
Main oscillator still runs
(stops).
Sub oscillator stops, halting
the CPU operation.
Reset
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.