MC908QT4MPE datasheet(95/184 Pages) FREESCALE

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Low Power Modes

MC68HC908QY/QT Family Data Sheet, Rev. 5

Freescale Semiconductor

again in the SIM and results in the internal bus frequency being one fourth of either the XTALCLK,

RCCLK, or INTCLK frequency.

11.5 Low Power Modes

The WAIT and STOP instructions put the MCU in low-power consumption standby modes.

11.5.1 Wait Mode

The WAIT instruction has no effect on the oscillator logic. BUSCLKX2 and BUSCLKX4 continue to drive

to the SIM module.

11.5.2 Stop Mode

The STOP instruction disables either the XTALCLK, the RCCLK, or INTCLK output, hence BUSCLKX2

and BUSCLKX4.

11.6 Oscillator During Break Mode

The oscillator continues to drive BUSCLKX2 and BUSCLKX4 when the device enters the break state.

11.7 CONFIG2 Options

Two CONFIG2 register options affect the operation of the oscillator module: OSCOPT1 and OSCOPT0.

All CONFIG2 register bits will have a default configuration. Refer to Chapter 5 Configuration Register

(CONFIG) for more information on how the CONFIG2 register is used.

Table 11-2 shows how the OSCOPT bits are used to select the oscillator clock source.

11.8 Input/Output (I/O) Registers

The oscillator module contains these two registers:

Oscillator status register (OSCSTAT)

Oscillator trim register (OSCTRIM)

Table 11-2. Oscillator Modes

OSCOPT1

OSCOPT0

Oscillator Modes

Internal oscillator

External oscillator

External RC

External crystal

MC908QT4MPE Datasheet(PDF) 95 Page - Freescale Semiconductor, Inc