Table 123. Filter Maximum Output Resolution (Peak Data Values From Filter Output); For Some Fosr Values; Table 124. Integrator Maximum Output Resolution; Output) For Some Iosr Values And Fosr = 256 And Sinc3 Filter Type (Largest Data) - ST STM32L4x6 Reference Manual

Digital filter for sigma delta modulators (DFSDM)

Table 123. Filter maximum output resolution (peak data values from filter output)

FOSR
x
4
8
32
64
128
256
1024 +/- 1024 +/- 1048576
For more information about Sinc filter type properties and usage, it is recommended to study
the theory about digital filters (more resources can be downloaded from internet).
21.3.9

Integrator unit

The integrator performs additional decimation and a resolution increase of data coming from
the digital filter. The integrator simply performs the sum of data from a digital filter for a given
number of data samples from a filter.
The integrator oversampling ratio parameter defines how many data counts will be summed
to one data output from the integrator. IOSR can be set in the range 1-256 (see IOSR[7:0]
bits description in DFSDMx_FCR register).
Table 124. Integrator maximum output resolution (peak data values from integrator
output) for some IOSR values and FOSR = 256 and Sinc
IOSR
x +/- FOSR. x +/- FOSR
4
32
128
256
21.3.10 Analog watchdog
The analog watchdog purpose is to trigger an external signal (break or interrupt) when an
analog signal reaches or crosses given maximum and minimum threshold values. An
interrupt/event/break generation can then be invoked.
Each analog watchdog will supervise serial data receiver outputs (after the analog watchdog
filter on each channel) or data output register (current injected or regular conversion result)
according to AWFSEL bit setting (in DFSDMx_CR1 register). The input channels to be
monitored or not by the analog watchdog x will be selected by AWDCH[7:0] in
DFSDMx_CR2 register.
620/1693
1 2
Sinc Sinc
2
+/- x +/- x
+/- 4 +/- 16
+/- 8 +/- 64
+/- 32 +/- 1024
+/- 64 +/- 4096
+/- 128 +/- 16384
+/- 256 +/- 65536
1 2
Sinc Sinc
2
. x +/- 2.FOSR
- -
- -
- -
- -
DocID024597 Rev 3

for some FOSR values

FastSinc Sinc
2
+/- 2x +/- x
+/- 32 +/- 64
+/- 128 +/- 512
+/- 2048 +/- 32768
+/- 8192 +/- 262144
+/- 32768 +/- 2097152
+/- 131072 +/- 16777216
+/- 2097152 +/- 1073741824
FastSinc
2
. x +/- FOSR
- +/- 67 108 864
- +/- 536 870 912
+/- 2 147 483
-
-
3 4
Sinc
3 4
+/- x
+/- 256
+/- 4096
+/- 1048576
+/- 16777216
+/- 268435456
Result can overflow on full scale
input (> 32-bit signed integer)
3
filter type (largest data)
3 4
Sinc Sinc
3 4
. x +/- FOSR
-
-
-
648
32
+/- 2 -
RM0351
5
Sinc
5
+/- x
+/- 1024
-
+/- 33554432
+/- 1073741824
5
Sinc
5
. x +/- FOSR . x
-
-
-
-