mc9s08ac16 Freescale Semiconductor, Inc, mc9s08ac16 Datasheet - Page 148

• Manufacturer Part Number: mc9s08ac16
• Description: Hcs08 Microcontrollers 8-bit Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.10
A clock mode is requested by writing to CLKS1:CLKS0 and the actual clock mode is indicated by
CLKST1:CLKST0. Provided minimum conditions are met, the status shown in CLKST1:CLKST0 should
be the same as the requested mode in CLKS1:CLKS0.
CLKST, and ICGOUT. It also shows the conditions for CLKS = CLKST or the reason CLKS ≠ CLKST.
148
(CLKST)
CLKST will not update immediately after a write to CLKS. Several bus cycles are required before CLKST updates to the new
value.
The reference frequency has no effect on ICGOUT in SCM, but the reference frequency is still used in making the comparisons
that determine the DCOS bit
After initial LOCK; will be ICGDCLK/2R during initial locking process and while FLL is re-locking after the MFD bits are changed.
Actual
Mode
SCM
(XX)
FBE
FEE
(00)
(01)
(10)
(11)
FEI
Off
Clock Mode Requirements
Desired
(CLKS)
Mode
SCM
(XX)
FBE
FBE
FEE
FEE
FBE
FEE
FEE
(10)
(00)
(01)
(10)
(11)
(01)
(11)
(10)
(11)
(11)
FEI
FEI
Off
If a crystal will be used before the next reset, then be sure to set REFS = 1
and CLKS = 1x on the first write to the ICGC1 register. Failure to do so will
result in “locking” REFS = 0 which will prevent the oscillator amplifier
from being enabled until the next reset occurs.
Range
X
X
X
X
X
X
X
X
0
0
0
1
(f
f
f
f
f
ICGIRCLK
ICGIRCLK
ICGIRCLK
Frequency
Reference
f
f
ICGIRCLK
REFERENCE
ICGIRCLK
ICGIRCLK
f
f
ICGERCLK
ICGERCLK
MC9S08AC16 Series Data Sheet, Rev. 0
0
0
0
0
/7
/7
/7
Table 8-9. ICG State Table
/7
/7
/7
(1)
(1)
(1)
2
)
PRELIMINARY
128/f
Comparison
Cycle Time
2/f
8/f
8/f
8/f
8/f
8/f
8/f
NOTE
ICGERCLK
ICGIRCLK
ICGIRCLK
ICGIRCLK
ICGIRCLK
ICGIRCLK
ICGIRCLK
ICGERCLK
—
—
—
—
Table 8-9
ICGDCLK/R
ICGERCLK/R
ICGERCLK/R
ICGDCLK/R
ICGDCLK/R
ICGDCLK/R
ICGDCLK/R
ICGDCLK/R
ICGDCLK/R
ICGDCLK/R
ICGOUT
shows the relationship between CLKS,
0
0
(2)
3
Conditions
CLKS = CLKST
ERCS = 1 and
ERCS = 1 and
Not switching
from FBE to
DCOS = 1
ERCS = 1
DCOS = 1
DCOS = 1
SCM
—
—
—
—
—
—
—
Freescale Semiconductor
1
for
DCOS = 0 or
LOCS = 1 &
DCOS = 0
ERCS = 0
ERCS = 0
ERCS = 0
ERCS = 0
ERCS = 1
CLKS1 ≠
Reason
CLKST
—
—
—
—
—
—