COMPONENT MAINTENANCE MANUAL
AVIATION PRODUCTS
Model FA5000
Rev. 02 Page 15
July 21/17
Description and Operation
23–70
−
30
Use or disclosure of information on this sheet is subject to
the restrictions on the cover page of this document.
When the Data Storage task starts, the first thing that it will do is make sure that the
CSMU hardware is present and that the memory needed for data storage within each par-
tition is contained in the CSMU. The system configuration table will contain information
about which type of CSMU is attached to the recorder. The recorder type dictates which
partitions need to be present.
Once the Data Storage task has verified proper operation and configuration of the CSMU,
it reads the NV RAM to find out where to start recording each of the data streams. If the
indices are corrupted, then it will scan the memory looking for the erase gap which indi-
cates where the recording last stopped. If the erase gap is found, then this will be where
the current record cycle will start. If an erase gap cannot be found, then the recording will
start at the top of memory.
Now that the Data Storage task knows where to start recording the data, it can start re-
ceiving data from the CVR task and the DataLink task. Each packet that is received from
these tasks contains a size parameter so that the Data Storage task knows how much
data to write. Once the packet is written, the Data Storage task turns around and reads
the same data that was just written and sends this data back to the task from which the
data originated. This is done to implement the read-after-write BITE functionality of the
recorder.
Each packet of data for the audio and DataLink partitions will be written in one 128 Kbyte
block until the end of the block is reached at which time the packet is written to the next
block in the next chip. This is because according to ED-112 specifications, the Audio
(CAM, and Voice) and DataLink partitions have to be designed such that complete loss of
data cannot result from the loss of a single memory device. This scheme meets the
ED-112 requirement that states that the recording medium shall be physically segregated
in such a way that the non-availability of a single memory device does not lead to the loss
of more than 16 seconds of contiguous data.
This task will manage the erase-ahead needed to ensure that new data is only written to
blocks of flash memory that have been erased. To do this, an erase is started when a
write takes place at the beginning of a block. For the Microphone, CAM, and DataLink
partitions, the erase occurs in the next block to be written. This block will always be in the
next consecutive memory chip.
The user will be able to set memory markers to mark a significant event in the data. Mem-
ory markers will be able to be set for any of the data streams. Memory markers will be
stored in the NV RAM to ensure that they remain valid through power cycles. Once a
wrap-around has occurred in the memory and the data pointed to by the memory marker
has been overwritten, the memory marker will be deleted from the NV RAM.
See Figure 9 – Data Storage Task Flowchart.
The document reference is online, please check the correspondence between the online documentation and the printed version.