ST STM32L4+ Series Reference Manual page 837

RM0432
Configuration of serial channels for PDM microphone input:
•
PDM microphone signals (data, clock) will be connected to DFSDM input serial channel
y (DATINy, CKOUT) pins.
•
Channel y will be configured: CHINSEL = 0 (input from given channel pins: DATINy,
CKINy).
•
Channel (y-1) (modulo 8) will be configured: CHINSEL = 1 (input from the following
channel ((y-1)+1) pins: DATINy, CKINy).
•
Channel y: SITP[1:0] = 0 (rising edge to strobe data) => left audio channel on channel
y.
•
Channel (y-1): SITP[1:0] = 1 (falling edge to strobe data) => right audio channel on
channel y-1.
•
Two DFSDM filters will be assigned to channel y and channel (y-1) (to filter left and
right channels from PDM microphone).
DATIN(y
max
CKIN(y
max
.
.
.
DATINy
CKINy
DATIN(y-1)
CKIN(y-1)
.
.
.
DATAIN0
CKIN0
Figure 192. Input channel pins redirection
(. . .)
)
)
.
.
.
.
.
.
(. . .)
Digital filter for sigma delta modulators (DFSDM)
CH(y )
max
Decode
.
.
.
CHy
Decode
CH(y-1)
Decode
.
.
.
CH0
Decode
RM0432 Rev 6
FLT(x )
max
.
.
.
FLT(x+1)
FLTx
.
.
.
FLT0
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