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Document # 001-20559 Rev. *D
Digital Clocks
25.3.8
OSC_CR2 Register
The Oscillator Control Register 2 (OSC_CR2) is used to
configure various features of internal clock sources and
clock nets.
Bit 7: PLLGAIN.
This is the only bit in the OSC_CR2 regis-
ter that directly influences the PLL. When set, this bit keeps
the PLL in a Low Gain mode. If this bit is held low, the lock
time is less than 10 ms. If this bit is held high, the lock time
is on the order of 50 ms. After lock is achieved, it is recom-
mended that this bit be forced high to decrease the jitter on
the output. If longer lock time is tolerable, the PLLGAIN bit
can be held high all the time.
Bit 2: EXTCLKEN.
When the EXTCLKEN bit is set, the
external clock becomes the source for the internal clock
tree, SYSCLK, which drives most PSoC device clocking
functions. All external and internal signals, including the 32
kHz clock, whether derived from the internal low speed
oscillator (ILO) or the crystal oscillator, are synchronized to
this clock source.
If an external clock is enabled, PLL mode should be off. The
external clock input is located on port P1[4]. When using this
input, the pin Drive mode should be set to High Z (not High
Z analog).
Bit 1: RSVD.
Reserved bit - This bit should always be 0.
Bit 0: SYSCLKX2DIS.
When set, the Internal Main Oscilla-
tor’s doubler is disabled. This results is a reduction of overall
device power, on the order of 1 mA. It is advised that any
application that does not require this doubled clock should
have it turned off.
For additional information, refer to the
.
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
1,E2h
PLLGAIN
EXTCLKEN
RSVD
SYSCLKX2
DIS
RW : 00
Содержание PSoC CY8C23533
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Страница 82: ...18 Document 001 20559 Rev D Internal Main Oscillator IMO ...
Страница 84: ...20 Document 001 20559 Rev D Internal Low Speed Oscillator ILO ...
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Страница 94: ...30 Document 001 20559 Rev D Phase Locked Loop PLL ...
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