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The resulting conversion time is generated using the parameters listed in in the preceding
table. Therefore, for bus clock and ADCK frequency equal to 20 MHz, the resulting
conversion time is 1.45 µs.
32.4.5.7 Hardware average function
The hardware average function can be enabled by setting SC3[AVGE]=1 to perform a
hardware average of multiple conversions. The number of conversions is determined by
the AVGS[1:0] bits, which can select 4, 8, 16, or 32 conversions to be averaged. While
the hardware average function is in progress, SC2[ADACT] will be set.
After the selected input is sampled and converted, the result is placed in an accumulator
from which an average is calculated once the selected number of conversions have been
completed. When hardware averaging is selected, the completion of a single conversion
will not set SC1n[COCO].
If the compare function is either disabled or evaluates true, after the selected number of
conversions are completed, the average conversion result is transferred into the data
result registers, Rn, and SC1n[COCO] is set. An ADC interrupt is generated upon the
setting of SC1n[COCO] if the respective ADC interrupt is enabled, that is,
SC1n[AIEN]=1.
Note
The hardware average function can perform conversions on a
channel while the MCU is in Wait or Normal Stop modes. The
ADC interrupt wakes the MCU when the hardware average is
completed if SC1n[AIEN] was set.
32.4.6 Automatic compare function
The compare function can be configured to check whether the result is less than or
greater-than-or-equal-to a single compare value, or, if the result falls within or outside a
range determined by two compare values. The compare mode is determined by
SC2[ACFGT], SC2[ACREN], and the values in the compare value registers, CV1 and
CV2. After the input is sampled and converted, the compare values in CV1 and CV2 are
used as described in the following table. There are six Compare modes as shown in the
following table.
Chapter 32 Analog-to-Digital Converter (ADC)
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
Freescale Semiconductor, Inc.
Preliminary
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