COMPONENT MAINTENANCE MANUAL
AVIATION RECORDERS
FA2100CVR
Rev. 15 Page 44
Apr. 14/16
Description and Operation
23–70–04
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to the restrictions on the cover page of this document.
B.
Software Operating States
The FA2100 CVR software operates in several states which include initialization, re-
cording, power down, data playback, bulk erase, and push to test. Of these states,
the CVR operates in the record state for most of its power on time. Each of the
states will be discussed in the following sections.
(1)
Initialization State
The SMP goes through the initialization sequence when reset is asserted as a
result of power up or watchdog timeout. The power up hardware reset inter-
rupt is connected directly to the SMP. Initialization consists of setting up the
run time environment and starting the software kernel. After the software ker-
nel is initialized, all of the required SMP tasks needed for CVR operation are
started. These include the Mode Executive, CVR Executive, NVRAM Manager,
Flash Manager, Fault Manager, Audio Channelizer, and Audio Reconstructer.
The Mode Executive provides the interface to the GSE if it is connected to the
recorder. It controls whether the CVR will progress into the record state or play-
back state for recovery of recorded audio.
The CVR Executive processes the input digital audio channel data and man-
ages the actual record or playback operations.
The Flash Manager acts as a server task supporting all accesses to the crash
protected flash memory devices. Likewise, the NVRAM Manager task provides
a similar interface function to the non
−
volatile RAM used for memory index and
configuration information storage.
The Fault Manager provides common processing for all fault conditions and no-
table events that are detected by the other software tasks.
The Audio Channelizer task “demultiplexes” mixed audio data from the TDM
bus interface and builds packets of channel specific audio data for storage in
the CSMU. The Audio Reconstructer task processes the individual audio chan-
nel streams, either in real time (using the read
−
after write CSMU data) or as
part of the audio data playback state back into a single stream for transmission
to the GSE via the TDM bus.
Once all the SMP tasks are running, record state initialization is controlled by
the CVR Executive task. It retrieves the record
−
location indices from NVRAM,
then performs a CRC and additional validation steps. If the indices cannot be
validated, the CSMU memory is scanned to find an appropriate record starting
point as evidenced by an erase gap. In the case where no erase gap can be
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