mc9s08sg4 Freescale Semiconductor, Inc, mc9s08sg4 Datasheet - Page 151

• Manufacturer Part Number: mc9s08sg4
• Description: 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

10.4
10.4.1
The seven states of the ICS are shown as a state diagram and are described below. The arrows indicate the
allowed movements between the states.
10.4.1.1
FLL engaged internal (FEI) is the default mode of operation and is entered when all the following
conditions occur:
Freescale Semiconductor
FLL Bypassed
External Low
Power(FBELP)
Field
IREFS=0
CLKS=10
BDM Disabled
and LP=1
1
0
Functional Description
Operational Modes
OSC Initialization — If the external reference clock is selected by ERCLKEN or by the ICS being in FEE, FBE,
or FBELP mode, and if EREFS is set, then this bit is set after the initialization cycles of the external oscillator
clock have completed. This bit is only cleared when either ERCLKEN or EREFS are cleared.
ICS Fine Trim — The FTRIM bit controls the smallest adjustment of the internal reference clock frequency.
Setting FTRIM will increase the period and clearing FTRIM will decrease the period by the smallest amount
possible.
FLL Engaged Internal (FEI)
Entered from any state
when MCU enters stop
Table 10-5. ICS Status and Control Register Field Descriptions (continued)
IREFS=0
CLKS=10
BDM Enabled
or LP =0
FLL Bypassed
External (FBE)
MC9S08SG8 MCU Series Data Sheet, Rev. 3
Figure 10-7. Clock Switching Modes
FLL Engaged
External (FEE)
FLL Engaged
Internal (FEI)
IREFS=1
CLKS=00
IREFS=0
CLKS=00
Stop
Description
Chapter 10 Internal Clock Source (S08ICSV2)
FLL Bypassed
Internal (FBI)
Returns to state that was active
before MCU entered stop, unless
RESET occurs while in stop.
IREFS=1
CLKS=01
BDM Enabled
or LP=0
FLL Bypassed
Internal Low
Power(FBILP)
IREFS=1
CLKS=01
BDM Disabled
and LP=1
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