
NON-DISCLOSURE
AGREEMENT
REQUIRED
Low-Power Modes
General Release Specification
MC68HC05C12A — Rev. 3.0
46
Low-Power Modes
MOTOROLA
Figure 6-1. Stop/Wait Mode Flowchart
6.3 Stop Mode
The STOP instruction places the MCU in its lowest-power consumption
mode. In stop mode, the internal oscillator is turned off, halting all
internal processing, including timer operation.
During stop mode, the TCR bits are altered to remove any pending timer
interrupt request and to disable any further timer interrupts. The timer
prescaler is cleared. The I bit in the condition code register is cleared to
enable external interrupts. All other registers and memory remain
1. FETCH RESET VECTOR
OR
2. SERVICE INTERRUPT
A. STACK
B. SET I BIT
C. VECTOR TO
INTERRUPT
ROUTINE
1. FETCH RESET VECTOR
OR
2. SERVICE INTERRUPT
A. STACK
B. SET I BIT
C. VECTOR TO
INTERRUPT
ROUTINE
Y
STOP
OSCILLATOR ACTIVE
TIMER CLOCK ACTIVE
PROCESSOR CLOCKS STOPPED
CLEAR I BIT
(IRQ)
EXTERNAL
RESET
TURN ON OSCILLATOR
WAIT FOR TIME
DELAY TO STABILIZE
RESTART
PROCESSOR CLOCK
WAIT
STOP OSCILLATOR
AND ALL CLOCKS
CLEAR I BIT
INTERRUPT
TIMER
INTERRUPT
(IRQ)
EXTERNAL
Y
N
INTERRUPT
SCI
Y
N
INTERRUPT
SPI
N
INTERRUPT