Digital filter for sigma delta modulators (DFSDM) RM0351
730/1830 DocID024597 Rev 5
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, 4, 6), for odd channel numbers (y = 1, 3, 5, 7)
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).
Bits 13:12 DATMPX[1:0]: Input data multiplexer for channel y
0:Data to channel y are taken from external serial inputs as 1-bit values. DFSDM_CHyDATINR
register is write protected.
1: Data to channel y are taken from internal analog to digital converter ADC
y+1
output register
update as 16-bit values (if ADC
y+1
is available). Data from ADCs are written into INDAT0[15:0]
part of DFSDM_CHyDATINR register.
2:Data to channel y are taken from internal DFSDM_CHyDATINR register by direct CPU/DMA write.
There can be written one or two 16-bit data samples according DATPACK[1:0] bit field setting.
3:Reserved
This value can be modified only when CHEN=0 (in DFSDM_CHyCFGR1 register).
Note: DATMPX[1:0] = 1 is reserved for STM32L475xx/476xx/486xx devices.
Bits 11:9 Reserved, must be kept at reset value.
Bit 8 CHINSEL: Channel inputs selection
0: Channel inputs are taken from pins of the same channel y.
1: Channel inputs are taken from pins of the following channel (channel (y+1) modulo 8).
This value can be modified only when CHEN=0 (in DFSDM_CHyCFGR1 register).
Bit 7 CHEN: Channel y enable
0: Channel y disabled
1: Channel y enabled
If channel y is enabled, then serial data receiving is started according to the given channel setting.
To Next Page
Loading...
