
DocID024597 Rev 5
701/1830
RM0351
Digital filter for sigma delta modulators (DFSDM)
756
24.2
DFSDM main features
•
Up to 8 multiplexed input digital serial channels:
–
configurable SPI interface to connect various
Σ∆
modulators
–
configurable Manchester coded 1 wire interface support
–
clock output for
Σ∆
modulator(s)
•
Alternative inputs from up to 8 internal digital parallel channels:
–
inputs with up to 16 bit resolution
–
internal sources: ADCs data
(a)
or memory (CPU/DMA write) data streams
•
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:
–
right bit-shifter on final data (0..31 bits)
•
Signed output data format
•
Automatic data offset correction (offset stored in register by user)
•
Continuous or single conversion
•
Start-of-conversion synchronization with:
–
software trigger
–
internal timers
–
external events
–
start-of-conversion synchronously with first DFSDM filter (DFSDM_FLT0)
•
Analog watchdog feature:
–
low value and high value data threshold registers
–
own configurable Sinc
x
digital filter (order = 1..3, oversampling ratio = 1..32)
–
input from output data register or from one or more input digital serial channels
–
continuous monitoring independently from standard conversion
•
Short-circuit detector to detect saturated analog input values (bottom and top ranges):
–
up to 8-bit counter to detect 1..256 consecutive 0’s or 1’s on input data stream
–
monitoring continuously each channel (8 serial channel transceiver outputs)
•
Break generation on analog watchdog event or short-circuit detector event
•
Extremes detector:
–
store minimum and maximum values of output data values
–
refreshed by software
•
DMA may be used to read the conversion data
•
Interrupts: end of conversion, overrun, analog watchdog, short-circuit, channel clock
absence
•
“regular” or “injected” conversions:
–
“regular” conversions can be requested at any time or even in continuous mode
without having any impact on the timing of “injected” conversions
a. STM32L496xx/4A6xx devices only.