Low Power Modes
5.6.4 CGM Oscillator Clock (CGMXCLK)
The CGMXCLK clock is output from the x-tal oscillator, RC oscillator or the internal oscillator. This clock
drives to CGM and other MCU sub-systems.
5.6.5 CGM Reference Clock (CGMRCLK)
This is buffered signal of CGMXCLK, it is used by the CGM as the phase-locked-loop (PLL) reference
clock.
5.6.6 Oscillator Clock to Time Base Module (OSCCLK)
The OSCCLK is the reference clock that drives the timebase module. See Chapter 10 Timebase Module
(TBM).
5.7 Low Power Modes
The WAIT and STOP instructions put the MCU in low-power consumption standby modes.
5.7.1 Wait Mode
The WAIT instruction has no effect on the oscillator module. CGMXCLK continues to drive to the clock
generator module, and OSCCLK continues to drive the timebase module.
5.7.2 Stop Mode
The STOP instruction disables the x-tal or the RC oscillator circuit, and hence the CGMXCLK clock stops
running. For continuous x-tal or RC oscillator operation in stop mode, set the STOP_XCLKEN (for x-tal)
or STOP_RCLKEN (for RC) bit to logic 1 before entering stop mode.
The internal oscillator clock continues operation in stop mode. It can be disabled by setting the
STOP_ICLKDIS bit to logic 1 before entering stop mode.
5.8 Oscillator During Break Mode
The oscillator continues to drive CGMXCLK when the device enters the break state.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
77
FREESCALE [ Freescale ]
