
Modes of Operation and Pin Descriptions
MC68HC05E6 — Rev. 1.0
22
Modes of Operation and Pin Descriptions
MOTOROLA
Low power modes
STOP
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 (and COP watchdog timer) operation.
The I-bit in the CCR is cleared to enable external interrupts. All other
registers, the remaining bits in the CTCSR, and memory contents
remain unaltered. All input/output lines remain unchanged. The
processor can be brought out of STOP mode only by an external
interrupt, a keyboard interrupt (if enabled), an LVI interrupt (if enabled),
or a reset (see
Figure 6). On the MC68HC05E6, the STOP instruction
can be disabled using a mask option, in which case it is executed as a
no operation (NOP).
NOTE:
When exiting STOP mode there is a 4064 cycle delay before normal
operation resumes.
WAIT
The WAIT instruction places the MCU in a low power consumption
mode, but WAIT mode consumes more power than STOP mode. All
CPU action is suspended, but the core timer, the 16-bit timer and the A/D
converter remain active. An external, keyboard or LVI interrupt or an
interrupt from the core timer or 16-bit timer, if enabled, will cause the
MCU to exit WAIT mode.
During WAIT mode, the I-bit in the CCR is cleared to enable interrupts.
All other registers, memory and input/output lines remain in their
previous state. The core timer interrupts may be enabled to allow a
10-pin