MC68HC908QY4CDW Datasheet, PDF (95/184 Pages) Freescale Semiconductor, Inc – Microcontrollers

Low Power Modes
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.
.
Table 11-2. Oscillator Modes
OSCOPT1
0
0
1
1
OSCOPT0
0
1
0
1
Oscillator Modes
Internal oscillator
External oscillator
External RC
External crystal
11.8 Input/Output (I/O) Registers
The oscillator module contains these two registers:
1. Oscillator status register (OSCSTAT)
2. Oscillator trim register (OSCTRIM)
MC68HC908QY/QT Family Data Sheet, Rev. 6
Freescale Semiconductor
95