Returns to state that was active
before MCU entered stop, unless
RESET occurs while in stop.
Stop
IREFS=1
CLKS=00
FLL Bypassed
Internal Low
Power(FBILP)
IREFS=1
CLKS=01
BDM Disabled
and LP=1
IREFS=1
CLKS=01
BDM Enabled
or LP=0
IREFS=0
CLKS=10
BDM Disabled
and LP=1
FLL Bypassed
External Low
Power(FBELP)
FLL Engaged
Internal (FEI)
FLL Bypassed
External (FBE)
FLL Engaged
External (FEE)
Internal (FBI)
IREFS=0
CLKS=00
IREFS=0
CLKS=10
BDM Enabled
or LP =0
FLL Bypassed
Entered from any state
when MCU enters stop
Figure 8-3. ICS clocking switching modes
The ICS_C1[IREFS] bit can be changed at anytime, but the actual switch to the newly
selected clock is shown by the ICS_S[IREFST] bit. When switching between FLL
engaged internal (FEI) and FLL engaged external (FEE) modes, the FLL will lock again
after the switch is completed.
The ICS_C1[CLKS] bits can also be changed at anytime, but the actual switch to the
newly selected clock is shown by the ICS_S[CLKST] bits. If the newly selected clock is
not available, the previous clock remains selected.
8.2.2.1 FLL engaged internal (FEI)
FLL engaged internal (FEI) is the default mode of operation and is entered when all of
the following conditions occur:
• ICS_C1[CLKS] bits are written to 0b
• ICS_C1[IREFS] bit is written to 1b
Chapter 8 Clock management
MC9S08PA4 Reference Manual, Rev. 5, 08/2017
NXP Semiconductors
157
Summary of Contents for MC9S08PA4
Page 1: ...MC9S08PA4 Reference Manual Supports MC9S08PA4 Document Number MC9S08PA4RM Rev 5 08 2017 ...
Page 2: ...MC9S08PA4 Reference Manual Rev 5 08 2017 2 NXP Semiconductors ...
Page 22: ...MC9S08PA4 Reference Manual Rev 5 08 2017 22 NXP Semiconductors ...
Page 28: ...System clock distribution MC9S08PA4 Reference Manual Rev 5 08 2017 28 NXP Semiconductors ...
Page 150: ...Port data registers MC9S08PA4 Reference Manual Rev 5 08 2017 150 NXP Semiconductors ...
Page 196: ...Human machine interfaces HMI MC9S08PA4 Reference Manual Rev 5 08 2017 196 NXP Semiconductors ...
Page 224: ...Instruction Set Summary MC9S08PA4 Reference Manual Rev 5 08 2017 224 NXP Semiconductors ...
Page 232: ...Functional Description MC9S08PA4 Reference Manual Rev 5 08 2017 232 NXP Semiconductors ...
Page 258: ...FTM Interrupts MC9S08PA4 Reference Manual Rev 5 08 2017 258 NXP Semiconductors ...
Page 294: ...Functional description MC9S08PA4 Reference Manual Rev 5 08 2017 294 NXP Semiconductors ...
Page 398: ...Resets MC9S08PA4 Reference Manual Rev 5 08 2017 398 NXP Semiconductors ...
Page 400: ...MC9S08PA4 Reference Manual Rev 5 08 2017 400 NXP Semiconductors ...