• 8-bit Single-Ended mode with the bus clock selected as the input clock source
• The input clock divide-by-1 ratio selected
• Bus frequency of 20 MHz
• Long sample time disabled
• High-speed conversion enabled
The conversion time for this conversion is calculated by using the Figure 28-62, and the
information provided in Table 28-70 through Table 28-74. The table below lists the
variables of Figure 28-62.
Table 28-77. Typical conversion time
Variable Time
SFCAdder 5 ADCK cycles + 5 bus clock cycles
AverageNum 1
BCT 17 ADCK cycles
LSTAdder 0 ADCK cycles
HSCAdder 2
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.
28.4.4.7 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.
Functional description
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
492 Freescale Semiconductor, Inc.
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