36.6.2.11 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.

Note: To perform oversampling and decimation, the Conversion Result Resolution field in the Control C register (CTRLC.RESSEL) must be set to 16-bit mode.

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 36-3. 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	4¹ = 4	0x2	0	0x1
14 bits	4² = 16	0x4	0	0x2
15 bits	4³ = 64	0x6	2	0x1
16 bits	4⁴ = 256	0x8	4	0x0