Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION
SECTION 6
LOW POWER MODES
The MC68HC05P4A is capable of running in a low-power mode in each of its
configurations. The WAIT and STOP instructions provide two modes that reduce
the power required for the MCU by stopping various internal clocks and/or the on-
chip oscillator. The STOP and WAIT instructions are not normally used if the COP
watchdog timer is enabled. The stop conversion mask option is used to modify the
behavior of the STOP instruction from stop mode to halt mode. The flow of the
stop, halt, and wait modes is shown in Figure 6-1.
6.1
STOP Instruction
The STOP instruction can result in one of two modes of operation, depending on
the stop conversion mask option. If the stop conversion is not chosen, the STOP
instruction will behave like a normal STOP instruction in the MC68HC05 Family
and place the MCU in the stop mode. If the stop conversion is chosen, the STOP
instruction will behave like a WAIT instruction (with the exception of a variable
delay at startup) and place the MCU in the halt mode.
6.1.1 Stop Mode
Execution of the STOP instruction without conversion to halt places the MCU in its
lowest power consumption mode. In the stop mode the internal oscillator is turned
off, halting all internal processing, including the COP watchdog timer. Execution
of the STOP instruction automatically clears the I bit in the condition code register
Rev. 2.0
6-1
For More Information On This Product,
Go to: www.freescale.com
FREESCALE [ Freescale ]
