MCU Internal Clock Generator (ICG)
MC1321x Reference Manual, Rev. 1.6
14-10
Freescale Semiconductor
14.3.8
Clock Mode Requirements
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.
shows the relationship between CLKS,
CLKST, and ICGOUT. It also shows the conditions for CLKS = CLKST or the reason CLKS
≠
CLKST.
NOTE
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.
FBE
(CLKST = 10)
10
0
Forced High
No
No
10
1
Real-Time
Yes
No
FEE
(CLKST = 11)
11
X
Real-Time
Yes
Yes
1
If ENABLE is high (waiting for external crystal start-up after exiting stop).
2
DCO clock will not be monitored until DCOS = 1 upon entering SCM from off or FLL Bypassed External Mode.
Table 14-2. ICG State Table
Actual
Mode
(CLKST)
Desired
Mode
(CLKS)
Range
Reference
Frequency
(f
REFERENCE
)
Comparison
Cycle Time
ICGOUT
Conditions
1
for
CLKS = CLKST
Reason
CLKS1 =
CLKST
Off
(XX)
Off
(XX)
X
0
—
0
—
—
FBE
(10)
X
0
—
0
—
ERCS = 0
SCM
(00)
SCM
(00)
X
f
ICGIRCLK
/7
2
8/f
ICGIRCLK
ICGDCLK/R
Not switching
from FBE to SCM
—
FEI
(01)
0
f
ICGIRCLK
/7
(1)
8/f
ICGIRCLK
ICGDCLK/R
—
DCOS = 0
FBE
(10)
X
f
ICGIRCLK
/7
(1)
8/f
ICGIRCLK
ICGDCLK/R
—
ERCS = 0
FEE
(11)
X
f
ICGIRCLK
/7
(1)
8/f
ICGIRCLK
ICGDCLK/R
—
DCOS = 0 or
ERCS = 0
FEI
(01)
FEI
(01)
0
f
ICGIRCLK
/7
8/f
ICGIRCLK
ICGDCLK/R
DCOS = 1
—
FEE
(11)
X
f
ICGIRCLK
/7
8/f
ICGIRCLK
ICGDCLK/R
—
ERCS = 0
Table 14-1. Clock Monitoring (When LOCD = 0) (continued)
Mode
CLKS
REFST
ERCS
External Reference
Clock
Monitored?
DCO Clock
Monitored?
Summary of Contents for freescale semiconductor MC13211
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Page 166: ...Modem Modes of Operation MC1321x Reference Manual Rev 1 6 7 22 Freescale Semiconductor...
Page 172: ...Modem Interrupt Description MC1321x Reference Manual Rev 1 6 8 6 Freescale Semiconductor...
Page 186: ...MCU Modes of Operation MC1321x Reference Manual Rev 1 6 10 8 Freescale Semiconductor...
Page 208: ...MCU Memory MC1321x Reference Manual Rev 1 6 11 22 Freescale Semiconductor...
Page 244: ...MCU Parallel Input Output MC1321x Reference Manual Rev 1 6 13 20 Freescale Semiconductor...
Page 288: ...MCU Central Processor Unit CPU MC1321x Reference Manual Rev 1 6 15 20 Freescale Semiconductor...
Page 308: ...MCU Timer PWM TPM Module MC1321x Reference Manual Rev 1 6 17 16 Freescale Semiconductor...
Page 338: ...Inter Integrated Circuit IIC MC1321x Reference Manual Rev 1 6 19 14 Freescale Semiconductor...
Page 372: ...Development Support MC1321x Reference Manual Rev 1 6 21 20 Freescale Semiconductor...