sc9s08mz16 Freescale Semiconductor, Inc, sc9s08mz16 Datasheet - Page 141

• Manufacturer Part Number: sc9s08mz16
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

ICGFLTLU/L = $xx
ICGTRM = $xx
Figure 8-13
8.6.3
In this example, the FLL will be used (in FEE mode) to multiply the external 4 MHz oscillator up to
40 MHz to achieve 20 MHz bus frequency.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT which corresponds to a 4 MHz bus frequency (f
During reset initialization software, the clock scheme will be set to FLL engaged, external (FEE). So
Solving for N / R gives:
Freescale Semiconductor
This is read only; should read DCOS = 1 before performing any time critical tasks
Only needed in self-clocked mode; FLT will be adjusted by loop to give 8.38 MHz DCO clock
Bits 15:12 unused
Bits 11:0 FLT
Bits 7:0
FLL LOCK STATUS.
INITIALIZE ICG
ICGC1 = $38
ICGC2 = $00
CONTINUE
LOCK = 1?
CHECK
RESET
Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz
shows flow charts for three conditions requiring ICG initialization.
YES
TRIM
N / R = 40 MHz /(4 MHz * 1) = 10; We can choose N = 10 and R = 1
NO
0000
No need for user initialization
Only need to write when trimming internal oscillator; not used when external
crystal is clock source
f
ICGOUT
Figure 8-13. ICG Initialization for FEE in Example #1
QUICK RECOVERY FROM STOP
RECOVERY FROM STOP
FLL LOCK STATUS.
= f
OSCSTEN = 1
CONTINUE
SC9S08MZ16 MCU Data Sheet, Rev. 1
LOCK = 1?
ext
CHECK
* P * N / R; P = 1, f
YES
NOTE: THIS WILL REQUIRE THE OSCILLATOR TO START AND
STABILIZE. ACTUAL TIME IS DEPENDENT ON CRYSTAL /RESONATOR
AND EXTERNAL CIRCUITRY.
NO
MINIMUM CURRENT DRAW IN STOP
ext
= 4.00 MHz
RECOVERY FROM STOP
FLL LOCK STATUS.
OSCSTEN = 0
CONTINUE
LOCK = 1?
CHECK
Bus
YES
).
Internal Clock Generator (S08ICGV4)
NO
Eqn. 8-3
Eqn. 8-4
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