
GENERAL RELEASE SPECIFICATION
July 7, 1997
MOTOROLA
LOW POWER MODES
MC68HC05PD6
6-2
REV 1.1
6.3.1 STOP Instruction
The STOP instruction places the MCU in its lowest power consumption mode. In
STOP mode, the internal main oscillator OSC is turned off, halting all internal
processing, including timer operations (Timer1, Timer2, and COP Watchdog
timer). Sub oscillator XOSC does not stop oscillating. Therefore if XOSC is used
as the clock source for COP, COP is still functional in STOP mode. See Section 8 on Clock Distribution.
During the 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 CCR is cleared to enable external interrupts. All other
registers and memory remain unaltered. All input/output lines remain unchanged.
The processor can be brought out of the STOP mode only by RESET or interrupt
from IRQ1, IRQ2, KWI, PDI, or RTC.
6.3.2 WAIT Instruction
The WAIT instruction places the MCU in a low-power consumption mode, but the
WAIT mode consumes more power than the STOP mode. All CPU action is
suspended, but on-chip peripherals and oscillators remain active. Any interrupt or
reset (including a COP reset) will cause the MCU to exit the WAIT mode.
During the 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
timers may be enabled to allow a periodic exit from the WAIT mode. WAIT mode
must be exited and the COP must be reset to prevent a COP time-out.
The reduction of power in the WAIT mode depends on how many of the on-chip
peripheral's clock can be shut down. Therefore the amount of power that will be
consumed is very dependent on the application and that it would be prohibitive to
test all parts for all variations. For these reasons the data sheet will include values
for a limited number of variations. These variations and the corresponding MAX
power consumptions will be decided upon after initial characterization of silicon.