MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1139
Preliminary—Subject to Change Without Notice
state machine are put in the initial state. The status register DECFILTER_MSR is also cleared. The
Coefficient registers are not affected by the SRES. In case there is some filter processing, this is aborted
and the last sample is discarded. The software reset command has high priority and the BSY bit is set
during its operation.
The configuration register DECFILTER_MCR is also not affected by soft-reset, except the bit SRES that
is self-negated and it is always read as 0.
When in debug or freeze mode, the soft-reset is executed but the filter remains in debug or freeze mode.
25.5.11 Interrupt Request Description
There are several interrupt request events that can be enabled using the module configuration register
DECFILTER_MCR. Basically, we can have the interrupt request issued:
•
when an input data is received,
•
when an output data is available, or
•
when an error has occurred.
The input data flag IDF is set when a data is received from Core processor when in stand alone mode, or
when a data is received in the PSI when it is not in stand alone mode.
The output data is available and its flag ODF is set when the input data sample is processed by the filter
and the decimation counter matches the decimation rate value.
It is defined as an error event in the decimation filter block:
•
the overflow in the filter,
•
the overrun in the decimation filter input or
•
the overrun in the decimation filter output.
The overflow occurs when the 2-complement result value from the MAC accumulator is out of the range
of values that can be stored in the tap register 4 (IIR) or in the output register.
The input overrun occurs when the input buffer is holding an input data and one more data is received by
the filter. Refer to
Section 25.5.3.1, “Input Buffer Overrun,”
for more details.
The output overrun occurs when a new data is sent to the output buffer but the previous data was not
handled yet. Refer to item
Section 25.5.4.1, “Output Buffer Overrun,”
for more details.
Despite the fact that these flags can be set with ISEL=0 due to the PSI, they are only cleared by the core
processor. Or by the soft reset command in the DEC_FILTER_MCR or by the clear flag registers in the
DEC_FILTER_MSR register.
25.5.12 Freeze Mode Description
The freeze mode operation is asserted using the FREN enable bit in the DEC_FILTER_MCR register
together with the bit FRZ in the same DEC_FILTER_MCR register or the module input ipg_debug.
It is not possible to enter in the freeze mode when the module is disabled by the configuration bit MDIS.