ST STM32F412 User Manual

RM0402 Rev 6 367/1163
RM0402 Digital filter for sigma delta modulators (DFSDM)
400
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).
14.4.9 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 DFSDM_FLTxFCR register).
14.4.10 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 DFSDM_FLTxCR1 register). The input channels to be
monitored or not by the analog watchdog x will be selected by AWDCH[3:0] in
DFSDM_FLTxCR2 register.
Table 88. Filter maximum output resolution (peak data values from filter output)
for some FOSR values
FOSR Sinc
1
Sinc
2
FastSinc Sinc
3
Sinc
4
Sinc
5
x +/- x +/- x
2
+/- 2x
2
+/- x
3
+/- x
4
+/- x
5
4 +/- 4 +/- 16 +/- 32 +/- 64 +/- 256 +/- 1024
8 +/- 8 +/- 64 +/- 128 +/- 512 +/- 4096 -
32 +/- 32 +/- 1024 +/- 2048 +/- 32768 +/- 1048576 +/- 33554432
64 +/- 64 +/- 4096 +/- 8192 +/- 262144 +/- 16777216 +/- 1073741824
128 +/- 128 +/- 16384 +/- 32768 +/- 2097152 +/- 268435456
256 +/- 256 +/- 65536 +/- 131072 +/- 16777216
Result can overflow on full scale
input (> 32-bit signed integer)
1024 +/- 1024 +/- 1048576 +/- 2097152 +/- 1073741824
Table 89. Integrator maximum output resolution (peak data values from integrator
output) for some IOSR values and FOSR = 256 and Sinc
3
filter type (largest data)
IOSR Sinc
1
Sinc
2
FastSinc Sinc
3
Sinc
4
Sinc
5
x +/- FOSR. x +/- FOSR
2
. x +/- 2.FOSR
2
. x +/- FOSR
3
. x +/- FOSR
4
. x +/- FOSR
5
. x
4 - - - +/- 67 108 864 - -
32 - - - +/- 536 870 912 - -
128 - - -
+/- 2 147 483
648
--
256 - - - +/- 2
32
--

ST STM32F412 Specifications

General

Brand	ST
Model	STM32F412
Category	Microcontrollers
Language	English