Freescale Semiconductor, Inc.
Ana log Sub syste m
CPFR2
Writing a logical one to this write-only flag clears the CPF2 flag in the
ASR. Writing a logical zero to this bit has no effect. Reading the
CPFR2 bit will return a logical zero. By default, this bit looks cleared
following a reset of the device.
1 = Clears the CPF2 flag bit
0 = No effect
CPFR1
Writing a logical one to this write-only flag clears the CPF1 flag in the
ASR. Writing a logical zero to this bit has no effect. Reading the
CPFR1 bit will return a logical zero. By default, this bit looks cleared
after a reset of the device.
1 = Clears the CPF1 flag bit
0 = No effect
NOTE: The CPFR1 and CPFR2 bits should be written with logical ones following
a power up of either comparator. This will clear out any latched CPF1 or
CPF2 flag bits which might have been set during the slower power up
sequence of the analog circuitry.
If both inputs to a comparator are above the maximum common-mode
input voltage (V –1.5V) the output of the comparator is indeterminate
DD
and may set the comparator flag. Applying a reset to the device may only
temporarily clear this flag as long as both inputs of a comparator remain
above the maximum common-mode input voltages.
VOFF
This read-write bit controls the addition of an offset voltage to the
bottom of the sample capacitor. It is not active unless the OPT bit in
the COPR at location $1FF0 is set. Any reads of the VOFF bit location
return a logical zero if the OPT bit is clear. During the time that the
sample capacitor is connected to an input (either HOLD or DHOLD
set) the bottom of the sample capacitor is connected to V . The
SS
VOFF bit is cleared by a reset of the device. For more information see
8.11 Sample and Hold.
1 = Enables approximately 100 mV offset to be added to the
sample voltage when both the HOLD and DHOLD control bits
are cleared
0 = Connects the bottom of the sample capacitor to V
SS
General Release Specification
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
Analog Subsystem
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