33.6.8 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, 4n 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 33-4. Configuration Required for Oversampling and Decimation
Result ResolutionNumber of Samples to AverageAVGCTRL.SAMPLENUM[3:0]Number of Automatic Right ShiftsAVGCTRL.ADJRES[2:0]
13 bits41 = 40x200x1
14 bits42 = 160x400x2
15 bits43 = 640x620x1
16 bits44 = 2560x840x0