...the world's most energy friendly microcontrollers
2014-07-02 - Tiny Gecko Family - d0034_Rev1.20
405
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Table 24.2. ADC Differential Conversion
Results
Input/Reference
Binary
Hex value
0.5
011111111111
7FF
0.25
001111111111
3FF
1/2048
000000000001
001
0
000000000000
000
-1/2048
111111111111
FFF
-0.25
101111111111
BFF
-0.5
100000000000
800
24.3.7.6 Resolution
The ADC gives out 12-bit results, by default. However, if full 12-bit resolution is not needed, it is possible
to speed up the conversion by selecting a lower resolution (N = 6 or 8 bits). For more information on the
accuracy of the ADC, the reader is referred to the electrical characteristics section for the device.
24.3.7.7 Oversampling
To achieve higher accuracy, hardware oversampling can be enabled individually for each mode (Set RES
in ADCn_SINGLECTRL/ADCn_SCANCTRL to 0x3). The oversampling rate (OVSRSEL in ADCn_CTRL)
can be set to any integer power of 2 from 2 to 4096 and the configuration is shared between the scan
and single sample mode (OVSRSEL field in ADCn_CTRL).
With oversampling, each selected input is sampled a number (given by the OVSR) of times, and the
results are filtered by a first order accumulate and dump filter to form the end result. The data presented in
the ADCn_SINGLEDATA and ADCn_SCANDATA registers are the direct contents of the accumulation
register (sum of samples). However, if the oversampling ratio is set higher than 16x, the accumulated
results are shifted to fit the MSB in bit 15 as shown in Table 24.3 (p. 405) .
Table 24.3. Oversampling Result Shifting and Resolution
Oversampling setting
# right shifts
Result Resolution # bits
2x
0
13
4x
0
14
8x
0
15
16x
0
16
32x
1
16
64x
2
16
128x
3
16
256x
4
16
512x
5
16
1024x
6
16
2048x
7
16
4096x
8
16
Summary of Contents for EFM32TG
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