STMicroelectronics SPC572L series Reference Manual page 838

Decimation Filter
integrator registers immediately. Integrator zero command from external signal or by
software (SZRO) affects the integrator registers and flags as follows:
•
DECFILTER_CINTVAL resets immediately;
•
DECFILTER_CINTCNT does not reset immediately; it is updated only upon a
DECFILTER_CINTVAL read, loaded with the number of integrated samples occurred
after the reset;
•
DECFILTER_FINTVAL and DECFILTER_FINTCNT do not reset immediately; being
updated only upon a new output request (see
a integrator software zero command (through SZRO bit) and an integrator output
request (through SRQ bit) are made at the same time, the registers
DECFILTER_FINTVAL and DECFILTER_FINTCNT are updated with the last internal
values before reset; the same applies to simultaneous integrator zero command and
output request by hardware signal;
•
the SSOVF and SCOVF flags do not negate; however, the internal overflow states
which assert SSOVF and SCOVF do reset immediately, so that the next output update
(either by hardware request, software request or DECFILTER_CINTVAL read) before
an overflow does not assert SSOVF/SCOVF.
Note: The integrator reset does not depend on the integrator enabling (see
Integrator enabling and
37.4.13.4 Integrator enabling and halting
Two mechanisms, enabling and halting, drive the integrator accumulation, allowing it to be
controlled by a combination of two distinct sources: both software, both hardware, or one
hardware and the other software. Values are accumulated when the integrator is enabled
and not halted. The integrator halt and enable states can be controlled in the following ways:
•
by hardware, through external signals ; the enabling and the selection of the signal
request modes is done through the DECFILTER_MXCR fields SENSEL and SHLTSEL,
respectively (see
Register
•
by software, through the same DECFILTER_MXCR fields SENSEL and SHLTSEL.
Note that these fields are in different bytes, so that two distinct, concurrent software
tasks can avoid coherency problems by changing the fields using byte read-modify-
write accesses.
Note: Enabling and halting do not affect output requests or integrator reset.
37.4.13.5 Integrator exceptions
Integrator may run into exception states due to the overflow of either the accumulated value
or the sample counter. Exceptions are flagged by the DECFILTER_MXSR bits SSE for sum
value exception, and SCE for counter exception. These flags generate an error interrupt if it
is enabled (see
838/2058
halting).
Section 37.3.2.3: Decimation Filter Module Extended Configuration
(DECFILTER_MXCR));
Section 37.4.10.1: Block interrupt
DocID027809 Rev 4
Section 37.4.13.2: Integrator
Section 37.4.13.4:
request).
RM0400
outputs); if