Document # 001-20559 Rev. *D
17
Internal Main Oscillator (IMO)
8.3.2
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 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 SYSCLKX2DIS is set, the
IMO’s doubler is disabled. This results in a reduction of over-
all 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
8.3.3
IMO_TR Register
The Internal Main Oscillator Trim Register (IMO_TR) is used
to manually center the oscillator’s output to a target fre-
quency.
The PSoC device specific value for 5V operation is loaded
into the Internal Main Oscillator Trim register (IMO_TR) at
boot time. The Internal Main Oscillator operates within spec-
ified tolerance over a voltage range of 4.75V to 5.25V, with
no modification of this register. If the PSoC device operates
at a lower voltage, user code must modify the contents of
this register. For operation in the voltage range of 3.3V ±
.3V, this is accomplished with a Table Read command to the
Supervisory ROM, which supplies a trim value for operation
in this range. For operation between these voltage ranges,
user code can interpolate the best value using both avail-
able factory trim values.
It is strongly recommended that the user not alter the
register value, unless Slow IMO mode is used.
Bits 7 to 0: Trim[7:0].
These bits are used to trim the Inter-
nal Main Oscillator. A larger value in this register increases
the speed of the oscillator.
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
SYSCLKX2DIS
RW : 00
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
1,E8h
Trim[7:0]
W : 00
Summary of Contents for PSoC CY8C23533
Page 4: ...Contents Overview 4 Document 001 20559 Rev D Section G Glossary 385 Index 401 ...
Page 16: ...Contents Overview 16 Document 001 20559 Rev D ...
Page 24: ...24 Document 001 20559 Rev D Section A Overview ...
Page 30: ...30 Document 001 20559 Rev D Pin Information ...
Page 54: ...54 Document 001 20559 Rev D Supervisory ROM SROM ...
Page 60: ...60 Document 001 20559 Rev D RAM Paging ...
Page 68: ...68 Document 001 20559 Rev D Interrupt Controller ...
Page 76: ...12 Document 001 20559 Rev D General Purpose IO GPIO ...
Page 82: ...18 Document 001 20559 Rev D Internal Main Oscillator IMO ...
Page 84: ...20 Document 001 20559 Rev D Internal Low Speed Oscillator ILO ...
Page 90: ...26 Document 001 20559 Rev D External Crystal Oscillator ECO ...
Page 94: ...30 Document 001 20559 Rev D Phase Locked Loop PLL ...
Page 106: ...42 Document 001 20559 Rev D Sleep and Watchdog ...
Page 228: ...164 Document 001 20559 Rev D Section D Digital System ...
Page 234: ...170 Document 001 20559 Rev D Array Digital Interconnect ADI ...
Page 278: ...214 Document 001 20559 Rev D Digital Blocks ...
Page 296: ...232 Document 001 20559 Rev D Analog Interface ...
Page 304: ...240 Document 001 20559 Rev D Analog Array ...
Page 308: ...244 Document 001 20559 Rev D Analog Input Configuration ...
Page 312: ...248 Document 001 20559 Rev D Analog Reference ...
Page 338: ...274 Document 001 20559 Rev D Section F System Resources ...
Page 354: ...290 Document 001 20559 Rev D Multiply Accumulate MAC ...
Page 374: ...310 Document 001 20559 Rev D I2C ...
Page 400: ...336 Document 001 20559 Rev D Section G Glossary ...