Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
840
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
Table 32-3. Averaging
32.6.8 Oversampling and Decimation
By using oversampling and decimation, the ADC resolution can be increased from 12 bits to up to 16 bits. To increase
the resolution by n bits, 4
the resolution by n bits, 4
n
samples must be accumulated. The result must then be shifted right by n bits. This right shift is
a combination of the automatic right shift and the value written to AVGCTRL.ADJRES. To obtain the correct resolution,
the ADJRES must be configured as described in the table below. This method will result in n bit extra LSB resolution.
the ADJRES must be configured as described in the table below. This method will result in n bit extra LSB resolution.
Table 32-4. Configuration Required for Oversampling and Decimation
32.6.9 Window Monitor
The window monitor allows the conversion result to be compared to some predefined threshold values. Supported
modes are selected by writing the Window Monitor Mode bit group in the Window Monitor Control register
(WINCTRL.WINMODE[2:0]). Thresholds are given by writing the Window Monitor Lower Threshold register (WINLT) and
Window Monitor Upper Threshold register (WINUT).
modes are selected by writing the Window Monitor Mode bit group in the Window Monitor Control register
(WINCTRL.WINMODE[2:0]). Thresholds are given by writing the Window Monitor Lower Threshold register (WINLT) and
Window Monitor Upper Threshold register (WINUT).
If differential input is selected, the WINLT and WINUT are evaluated as signed values. Otherwise they are evaluated as
unsigned values.
unsigned values.
Number of
Accumulated
Samples
Accumulated
Samples
AVGCTRL.
SAMPLENUM
SAMPLENUM
Intermediate
Result
Precision
Result
Precision
Number of
Automatic
Right Shifts
Automatic
Right Shifts
Division
Factor
Factor
AVGCTRL.
ADJRES
ADJRES
Total
Number
of Right
Shifts
Number
of Right
Shifts
Final
Result
Precision
Result
Precision
Automatic
Division
Factor
Division
Factor
1
0x0
12 bits
0
1
0x0
12 bits
0
2
0x1
13
0
2
0x1
1
12 bits
0
4
0x2
14
0
4
0x2
2
12 bits
0
8
0x3
15
0
8
0x3
3
12 bits
0
16
0x4
16
0
16
0x4
4
12 bits
0
32
0x5
17
1
16
0x4
5
12 bits
2
64
0x6
18
2
16
0x4
6
12 bits
4
128
0x7
19
3
16
0x4
7
12 bits
8
256
0x8
20
4
16
0x4
8
12 bits
16
512
0x9
21
5
16
0x4
9
12 bits
32
1024
0xA
22
6
16
0x4
10
12 bits
64
Reserved
0xB –0xF
0x0
12 bits
0
Result
Resolution
Resolution
Number of Samples
to Average
to Average
AVGCTRL.SAMPLENUM[3:0]
Number of
Automatic Right
Shifts
Automatic Right
Shifts
AVGCTRL.ADJRES[2:0]
13 bits
4
1
= 4
0x2
0
0x1
14 bits
4
2
= 16
0x4
0
0x2
15 bits
4
3
= 64
0x6
2
0x1
16 bits
4
4
= 256
0x8
4
0x0