Datasheet
Functional overview STM32L476xx
46/270 DS10198 Rev 8
hardware. DFSDM features optional parallel data stream inputs from microcontrollers
memory (through DMA/CPU transfers into DFSDM).
DFSDM transceivers support several serial interface formats (to support various
modulators). DFSDM digital filter modules perform digital processing according user
selected filter parameters with up to 24-bit final ADC resolution.
The DFSDM peripheral supports:
• 8 multiplexed input digital serial channels:
– configurable SPI interface to connect various SD modulator(s)
– configurable Manchester coded 1 wire interface support
– PDM (Pulse Density Modulation) microphone input support
– maximum input clock frequency up to 20 MHz (10 MHz for Manchester coding)
– clock output for SD modulator(s): 0..20 MHz
• alternative inputs from 8 internal digital parallel channels (up to 16 bit input resolution):
– internal sources: device memory data streams (DMA)
• 4 digital filter modules with adjustable digital signal processing:
–Sinc
x
filter: filter order/type (1..5), oversampling ratio (up to 1..1024)
– integrator: oversampling ratio (1..256)
• up to 24-bit output data resolution, signed output data format
• automatic data offset correction (offset stored in register by user)
• continuous or single conversion
• start-of-conversion triggered by:
– software trigger
– internal timers
– external events
– start-of-conversion synchronously with first digital filter module (DFSDM1_FLT0)
• analog watchdog feature:
– low value and high value data threshold registers
– dedicated configurable Sincx digital filter (order = 1..3, oversampling ratio = 1..32)
– input from final output data or from selected input digital serial channels
– continuous monitoring independently from standard conversion
• short circuit detector to detect saturated analog input values (bottom and top range):
– up to 8-bit counter to detect 1..256 consecutive 0’s or 1’s on serial data stream
– monitoring continuously each input serial channel
• break signal generation on analog watchdog event or on short circuit detector event
• extremes detector:
– storage of minimum and maximum values of final conversion data
– refreshed by software
• DMA capability to read the final conversion data
• interrupts: end of conversion, overrun, analog watchdog, short circuit, input serial
channel clock absence
• “regular” or “injected” conversions:
– “regular” conversions can be requested at any time or even in continuous mode
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