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Frequency Modulated Phase-Locked Loop (FMPLL)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
7-5
NOTE
If LOLF has been set previously (due to an unexpected loss of lock
condition) and then cleared (by writing a 1), a change of the MFD, PREDIV
or DEPTH fields can cause the LOLF to be set again which can trigger an
interrupt request if LOLIRQ bit is set. In addition, changing the RATE bit
will also set the LOLF regardless of previous conditions.
The Loss of Lock Interrupt Request enable in the Synthesizer Control
Register (FMPLL_SYNCR[LOLIRQ]) should be cleared before any
change to the multiplication factor (MFD), PREDIV, modulation depth
(DEPTH), or modulation rate (RATE) to avoid unintentional interrupt
requests. After the PLL has locked (LOCK=1), LOLF should be cleared (by
writing a 1) and LOLIRQ may be set again if required.
7.3.2.2
FMPLL Enhanced Synthesizer Control Register 1 (ESYNCR1)
This is one of two FMPLL synthesizer control registers that are used to access enhanced features in the
FMPLL. The bit fields in the ESYNCR1 behave as described in
.
CALDONE
Calibration Complete. The CALDONE bit is an indication of whether the calibration sequence has been
completed since the last time modulation was enabled. If CALDONE = 0 then the calibration sequence is in
progress or modulation is disabled. If CALDONE = 1 then the calibration sequence has been completed, and
frequency modulation is operating.
0 Calibration not complete.
1 Calibration complete.
CALPASS
Calibration Passed. The CALPASS bit tells whether the calibration routine was successful. If CALPASS = 1 and
CALDONE = 1 then the routine was successful. If CALPASS = 0 and CALDONE = 1, then the routine was
unsuccessful. When the calibration routine is initiated the CALPASS is asserted. CALPASS remains asserted
until modulation is disabled by clearing the EDEPTH bits in the ESYNCR2 register or a failure occurs within the
FMPLL calibration sequence.
0 Calibration unsuccessful,
1 Calibration successful.
If calibration is unsuccessful, then actual depth is not guaranteed to match the desired depth
Table 7-3. System Clock Status Per Mode
MODE
PLLSEL
PLLREF
Clock Mode
0
X
X
PLL Off mode
1
0
0
Reserved
1
1
0
Normal PLL mode with external clock reference
1
1
1
Normal PLL mode with crystal clock reference
Table 7-2. SYNSR Register Field Descriptions (continued)
Field
Description
Summary of Contents for PXN2020
Page 1: ...PXN20 Microcontroller Reference Manual Devices Supported PXN2020 PXN2120 PXN20RM Rev 1 06 2011...
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Page 64: ...Introduction PXN20 Microcontroller Reference Manual Rev 1 1 22 Freescale Semiconductor...
Page 112: ...Signal Description PXN20 Microcontroller Reference Manual Rev 1 3 44 Freescale Semiconductor...
Page 118: ...Resets PXN20 Microcontroller Reference Manual Rev 1 4 6 Freescale Semiconductor...
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