Datasheet

...........continued
Number of
Accumulated
Samples
AVGCTRL.
SAMPLENUM
Intermediate
Result
Precision
Number of
Automatic
Right Shifts
Division
Factor
AVGCTRL.
ADJRES
Total Number
of Right
Shifts
Final Result
Precision
Automatic
Division
Factor
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
45.6.2.11 Oversampling and Decimation
By using oversampling and decimation, the ADC resolution can be increased from 12 bits up to 16 bits,
for the cost of reduced effective sampling rate.
To increase the resolution by n bits, 4
n
samples must be accumulated. The result must then be right
shifted 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.
Table 45-4. Configuration Required for Oversampling and Decimation
Result
Resolution
Number of
Samples to
Average
AVGCTRL.SAMPLENUM[3:0] Number of
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
45.6.2.12 Window Monitor
The window monitor feature allows comparing the conversion result in the RESULT register to predefined
threshold values.
The window mode is selected by writing the Window Monitor Mode bits in the Control B register
(CTRLB.WINMODE). Threshold values must be written in the Window Monitor Lower Threshold register
(WINLT) and Window Monitor Upper Threshold register (WINUT).
When the Window Single Sample (CTRLB.WINSS) bit is written to '1', the window comparator is working
on each sample instead of the accumulated value. The number of samples matching with window
comparator is available on Window Comparator Counter bits (STATUS.WCC).
In differential mode, WINLT and WINUT are evaluated as signed values. Otherwise they are evaluated as
unsigned values. The significant WINLT and WINUT bits are given by the precision selected in the
Conversion Result Resolution bit group in the Control B register (CTRLB.RESSEL). This means that for
SAM D5x/E5x Family Data Sheet
ADC – Analog-to-Digital Converter
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1594