XC886/888CLM
Analog-to-Digital Converter
User’s Manual
16-20
V1.3, 2010-02
ADC, V 1.0
16.4.7.3
Data Reduction Filter
Each result register can be controlled to enable or disable the data reduction filter. The
data reduction block allows the accumulation of conversion results for anti-aliasing
filtering or for averaging.
Figure 16-10 Data Reduction Flow
If DRC is 0 and a new conversion result comes in, DRC is reloaded with its reload value
(defined by bit DRCTR in the result control register) and the value of 0 is added to the
conversion result (instead of the previous result register content). Then, the complete
result is stored in the selected result register. If the reload value is 0 (data reduction filter
disabled), accumulation is done over one conversion. Hence, a result event is generated
and the valid bit (VF) for the result register becomes set. If the reload value is 1 (data
reduction filter enabled), accumulation is done over two conversions. In this case, neither
a result event is generated nor the valid bit is set.
If DRC is 1 and a new conversion result comes in, the data reduction filter adds the
incoming result to the value already stored in the result register and decrements DRC.
c0
conversion
ready
c1
c2
c3
c4
c5
c6
c7
running
conversion
c8
delivered
result
r0
r1
r2
r3
r4
r5
r6
r7
data reduction counter
DRC
1
0
1
0
1
0
1
0
0
content of
result register x
r0
r0 +
r1
r2
r2 +
r3
0
r4
r4 +
r5
r6
r6 +
r7
valid flag for result register x
VFx
DRCT
R =
1
DRC
0
0
0
0
0
0
0
0
0
content of
result register x
r0
r1
r2
r3
0
r4
r5
r6
r7
VFx
DRCT
R =
0
*