28.6.6 Accumulation

The result from multiple consecutive conversions can be accumulated. The number of samples to be accumulated is specified by the Number of Samples to be Collected field in the Average Control register (AVGCTRL.SAMPLENUM). When accumulating more than 16 samples, the result will be too large to match the 16-bit RESULT register size. To avoid overflow, the result is right shifted automatically to fit within the available register size. The number of automatic right shifts is specified in the table below.

Note: To perform the accumulation of two or more samples, the Conversion Result Resolution field in the Control B register (CTRLB.RESSEL) must be set.
Table 28-2. Accumulation
Number of Accumulated Samples AVGCTRL. SAMPLENUM Intermediate Result Precision Number of Automatic Right Shifts Final Result Precision Automatic Division Factor
1 0x0 12 bits 0 12 bits 0
2 0x1 13 bits 0 13 bits 0
4 0x2 14 bits 0 14 bits 0
8 0x3 15 bits 0 15 bits 0
16 0x4 16 bits 0 16 bits 0
32 0x5 17 bits 1 16 bits 2
64 0x6 18 bits 2 16 bits 4
128 0x7 19 bits 3 16 bits 8
256 0x8 20 bits 4 16 bits 16
512 0x9 21 bits 5 16 bits 32
1024 0xA 22 bits 6 16 bits 64
Reserved 0xB - 0xF 12 bits 12 bits 0