40.6.2.11 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 40-3. 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