33.6.6 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.
| 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 |