38.6.2.10 Averaging

Averaging is a feature that increases the sample accuracy, at the cost of a reduced sampling rate. This feature is suitable when operating in noisy conditions.

Averaging is done by accumulating m samples, as described in 38.6.2.9 Accumulation, then dividing the result by m. The averaged result is available in the RESULT register. The number of samples to be accumulated is specified by writing to AVGCTRL.SAMPLENUM as shown in Table 38-2.

The division is obtained by a combination of the automatic right shift described above, and an additional right shift that must be specified by writing to the Adjusting Result/Division Coefficient field in AVGCTRL (AVGCTRL.ADJRES), as described in Table 38-2.

Note: To perform the averaging of two or more samples, the Conversion Result Resolution field in the Control C register (CTRLC.RESSEL) must be set.

Averaging AVGCTRL.SAMPLENUM samples will reduce the un-averaged sampling rate by a factor 1 AVGCTRL.SAMPLENUM .

When the averaged result is available, the INTFLAG.RESRDY bit will be set.

Table 38-2. Averaging
Number of Accumulated Samples AVGCTRL. SAMPLENUM Intermediate Result Precision Number of Automatic Right Shifts Division Factor AVGCTRL.ADJRES Total Number of Right Shifts Final Result Precision Automatic Division Factor
1 0x0 12 bits 0 1 0x0 12 bits 0
2 0x1 13 0 2 0x1 1 12 bits 0
4 0x2 14 0 4 0x2 2 12 bits 0
8 0x3 15 0 8 0x3 3 12 bits 0
16 0x4 16 0 16 0x4 4 12 bits 0
32 0x5 17 1 16 0x4 5 12 bits 2
64 0x6 18 2 16 0x4 6 12 bits 4
128 0x7 19 3 16 0x4 7 12 bits 8
256 0x8 20 4 16 0x4 8 12 bits 16
512 0x9 21 5 16 0x4 9 12 bits 32
1024 0xA 22 6 16 0x4 10 12 bits 64
Reserved 0xB –0xF 0x0 12 bits 0