MC68HC08GP32A Datasheet, PDF (93/258 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 9
Low-Power Modes
9.1 Introduction
The MCU may enter two low-power modes: wait mode and stop mode. They are common to all HC08
MCUs and are entered through instruction execution. This section describes how each module acts in the
low-power modes.
9.1.1 Wait Mode
The WAIT instruction puts the MCU in a low-power standby mode in which the CPU clock is disabled but
the bus clock continues to run. Power consumption can be further reduced by disabling the LVI module
and/or the timebase module through bits in the mask option (MOR) register. See Chapter 11 Mask Option
Registers (MOR2 and MOR1).
9.1.2 Stop Mode
Stop mode is entered when a STOP instruction is executed. The CPU clock is disabled and the bus clock
is disabled if the OSCSTOPENB bit in the MOR register is 0. See Chapter 11 Mask Option Registers
(MOR2 and MOR1).
9.2 Analog-to-Digital Converter (ADC)
9.2.1 Wait Mode
The ADC continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC
can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power
down the ADC by setting ADCH4–ADCH0 bits in the ADC status and control register before executing the
WAIT instruction.
9.2.2 Stop Mode
The ADC module is inactive after the execution of a STOP instruction. Any pending conversion is aborted.
ADC conversions resume when the MCU exits stop mode after an external interrupt. Allow one
conversion cycle to stabilize the analog circuitry.
MC68HC08GP32A • MC68HC08GP16A Data Sheet, Rev. 1.0
Freescale Semiconductor
93