RM0402 Rev 6 377/1163
RM0402 Digital filter for sigma delta modulators (DFSDM)
400
Bit 31 DFSDMEN: Global enable for DFSDM interface
0: DFSDM interface disabled
1: DFSDM interface enabled
If DFSDM interface is enabled, then it is started to operate according to enabled y channels and
enabled x filters settings (CHEN bit in DFSDM_CHyCFGR1 and DFEN bit in DFSDM_FLTxCR1).
Data cleared by setting DFSDMEN=0:
–all registers DFSDM_FLTxISR are set to reset state (x = 0..1)
–all registers DFSDM_FLTxAWSR are set to reset state (x = 0..1)
Note: DFSDMEN is present only in DFSDM_CH0CFGR1 register (channel y=0)
Bit 30 CKOUTSRC: Output serial clock source selection
0: Source for output clock is from system clock
1: Source for output clock is from audio clock
–I2S clock selected by CKDFSDM1ASEL bit (Section 6.3.24: RCC Dedicated Clocks Configuration
Register (RCC_DCKCFGR))
This value can be modified only when DFSDMEN=0 (in DFSDM_CH0CFGR1 register).
Note: CKOUTSRC is present only in DFSDM_CH0CFGR1 register (channel y=0)
Bits 29:24 Reserved, must be kept at reset value.
Bits 23:16 CKOUTDIV[7:0]: Output serial clock divider
0: Output clock generation is disabled (CKOUT signal is set to low state)
1- 255: Defines the division of system clock for the serial clock output for CKOUT signal in range 2 -
256 (Divider = CKOUTDIV+1).
CKOUTDIV also defines the threshold for a clock absence detection.
This value can only be modified when DFSDMEN=0 (in DFSDM_CH0CFGR1 register).
If DFSDMEN=0 (in DFSDM_CH0CFGR1 register) then CKOUT signal is set to low state (setting is
performed one DFSDM clock cycle after DFSDMEN=0).
Note: CKOUTDIV is present only in DFSDM_CH0CFGR1 register (channel y=0)
Bits 15:14 DATPACK[1:0]: Data packing mode in DFSDM_CHyDATINR register.
0:Standard: input data in DFSDM_CHyDATINR register are stored only in INDAT0[15:0]. To empty
DFSDM_CHyDATINR register one sample must be read by the DFSDM filter from channel y.
1: Interleaved: input data in DFSDM_CHyDATINR register are stored as two samples:
–first sample in INDAT0[15:0] (assigned to channel y)
–second sample INDAT1[15:0] (assigned to channel y)
To empty DFSDM_CHyDATINR register, two samples must be read by the digital filter from
channel y (INDAT0[15:0] part is read as first sample and then INDAT1[15:0] part is read as next
sample).
2: Dual: input data in DFSDM_CHyDATINR register are stored as two samples:
–first sample INDAT0[15:0] (assigned to channel y)
–second sample INDAT1[15:0] (assigned to channel y+1)
To empty DFSDM_CHyDATINR register first sample must be read by the digital filter from channel
y and second sample must be read by another digital filter from channel y+1. Dual mode is
available only on even channel numbers (y = 0, 2), for odd channel numbers (y = 1, 3)
DFSDM_CHyDATINR is write protected. If an even channel is set to dual mode then the following
odd channel must be set into standard mode (DATPACK[1:0]=0) for correct cooperation with even
channel.
3: Reserved
This value can be modified only when CHEN=0 (in DFSDM_CHyCFGR1 register).
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