DocID024597 Rev 3 479/1693
RM0351 Analog-to-digital converters (ADC)
540
There are no changes for conversion timings in oversampled mode: the sample time is
maintained equal during the whole oversampling sequence. A new data is provided every N
conversions, with an equivalent delay equal to N x T
CONV
= N x (t
SMPL
+ t
SAR
). The flags are
set as follow:
• the end of the sampling phase (EOSMP) is set after each sampling phase
• the end of conversion (EOC) occurs once every N conversions, when the oversampled
result is available
• the end of sequence (EOS) occurs once the sequence of oversampled data is
completed (i.e. after N x sequence length conversions total)
Single ADC operating modes support when oversampling
In oversampling mode, most of the ADC operating modes are maintained:
• Single or continuous mode conversions
• ADC conversions start either by software or with triggers
• ADC stop during a conversion (abort)
• Data read via CPU or DMA with overrun detection
• Low-power modes (AUTDLY)
• Programmable resolution: in this case, the reduced conversion values (as per RES[1:0]
bits in ADCx_CFGR1 register) are accumulated, truncated, rounded and shifted in the
same way as 12-bit conversions are
Note: The alignment mode is not available when working with oversampled data. The ALIGN bit in
ADCx_CFGR1 is ignored and the data are always provided right-aligned.
Note: Offset correction is not supported in oversampling mode. When ROVSE and/or JOVSE bit is
set, the value of the OFFSETy_EN bit in ADCx_OFRy register is ignored (considered as
reset).
Table 95. Maximum output results versus N and M (gray cells indicate truncation)
Over
sampling
ratio
Max
Raw data
No-shift
OVSS =
0000
1-bit
shift
OVSS =
0001
2-bit
shift
OVSS =
0010
3-bit
shift
OVSS =
0011
4-bit
shift
OVSS =
0100
5-bit
shift
OVSS =
0101
6-bit
shift
OVSS =
0110
7-bit
shift
OVSS =
0111
8-bit
shift
OVSS =
1000
2x 0x1FFE 0x1FFE 0x0FFF 0x0800 0x0400 0x0200 0x0100 0x0080 0x0040 0x020
4x 0x3FFC 0x3FFC 0x1FFE 0x0FFF 0x0800 0x0400 0x0200 0x0100 0x0080 0x0040
8x 0x7FF8 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x0800 0x0400 0x0200 0x0100 0x0080
16x 0xFFF0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x0800 0x0400 0x0200 0x0100
32x 0x1FFE0
0xFFE0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x0800 0x0400 0x0200
64x 0x3FFC0
0xFFC0 0xFFE0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x0800 0x0400
128x 0x7FF80
0xFF80 0xFFC0 0xFFE0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x0800
256x 0xFFF00
0xFF00 0xFF80 0xFFC0 0xFFE0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF
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