ST STM32F412

Digital filter for sigma delta modulators (DFSDM) RM0402
366/1163 RM0402 Rev 6
reach the required output data rates and required output data resolution. The configurable
parameters are:
• Filter order/type: (see FORD[2:0] bits in DFSDM_FLTxFCR register):
–FastSinc
–Sinc
1
–Sinc
2
–Sinc
3
–Sinc
4
–Sinc
5
• Filter oversampling/decimation ratio (see FOSR[9:0] bits in DFSDM_FLTxFCR
register):
– FOSR = 1-1024 - for FastSinc filter and Sinc
x
filter x = F
ORD
= 1..3
– FOSR = 1-215 - for Sinc
x
filter x = F
ORD
= 4
– FOSR = 1-73 - for Sinc
x
filter x = F
ORD
= 5
The filter has the following transfer function (impulse response in H domain):
• Sinc
x
filter type:
• FastSinc filter type:
Figure 74. Example: Sinc
3
filter response
Hz()
1z
FOSR–
–
1z
1–
–
-----------------------------



x
=
Hz()
1z
FOSR–
–
1z
1–
–
-----------------------------



2
1z
2FOSR⋅()–
+()⋅=
Normalized frequency (fIN/fDATA )
Gain (dB)
MS30770V1