Products 05: Inter-Experiment Link
DESC: Products #05 Flux gate magnetometer dump
HIST: 18-04-96 AMD Created file from 2.04 UC version. Removed WEC related duties
and re-designed the FGM collecting procedure
05-11-96 AMD Resync'ed the TLM format procedure to FGM interrupt 9th component reading, and redefined the interrupt entry
mask for FGM interrupt to allow a fastest FGM service (no nest)
The TLM format sync on the 2nd B component has been avoided
because otherwise a dummy delay should be added to be sure
the previous ICI block request (in Hi rate TLM) were really over (too early trigger due to by sub-system address decoding).
17-02-96 AMD Forced a dummy FGM boot int sequence INI_FGM_BOT to supply a valid vector link during the OS booting.
30-08-97 AMD Sync'ed the FGM task data collection to the TLM Format event (evt_tlm).
NOTE: PRODUCT GENERATION
Product #5, FGM Dump, consists of 256 consecutive 16-bit
raw FGM data words read from the FGM IEL interface. The
words are collected as they arrive at the FGM interface
at approximately 2.6ms and 490us for the shortest intervals (LBR).
A product is passed to the telemetry interface when 256 16-bit words
have been collected (about 665 ms). The FGM IEL interface
is 16 bits wide in two compliment format.
The range information and supplementary sensors information
(Primary, secondary, dual mag) are expected to be transmitted
to ground via the HK filed 3 which not accessible by Esic.
However the range information it is not used on board and
pitch angle products P33 and P34 utilize the FGM components for
slice selection. However for such computation the ratio of
two components is involved and the range information can by
neglected.
The FGM continuously packs the vectors words and transfers
the words across the FGM I/F. Collection begins with the first
vector after the FGM re-sync occurring immediately after the Format
pulse.
Product # 16-b Buffer Pkt #
Number Words Size Size Pkts
------- ----- ------- ------ ----
#5 256 256 258 1
Sizes are in words. Packet size includes 2-word pkt hdr.
When the product collection is complete, the buffer of data
is sent to the product telemetry sub-task which puts the
packet in the telemetry packet queue. Generic sub-task
routines are used by each of the product tasks.
The tasks will double-buffer the data only if enough memory
is available. Otherwise, only one buffer will be allocated.
If there isn't enough memory for at least one buffer, then
an error is posted and the product task is deleted.
COLLECTION BUFFERS
Product #5 FGM Dump
Collection Buffer:
Offset Data
dec hex B
--- --- ---
0 0 PSx
1 1 PSy
2 2 PSs
3 3 PSx | SSx
4 4 PSy | SSy
5 5 PSs | SSz
6 6 PSx
7 7 PSy
8 8 PSs
9 9 PSx | SSx
10 A PSy | SSy
11 B PSs | SSz
.. ..
253 FD PSx | SSx
254 FE PSy | SSy
255 FF PSs | SSz
Data are two complimented and are encoded as they are. SSx,SSy,SSz
secondary sensor components will be present only if the FGM will
operate in '64 Hz dual mag mode'. Otherwise the primary sensor PSx,
PSy,PSz components will fill all the packet ("128 Hz primary mode").
TLM PACKET BUFFERS
The collection buffer is copied unchanged to the telemetry
packet buffer.
MEMORY USE
The collection buffer memory is reused for the telemetry
packet buffer. In addition four words are allocated just
before the collection buffer for a 2-word packet handling
structure and 2-word packet header. Memory use is:
Prod #5
Length
(words) Description
------ ---------------
2 packet handling structure
2 packet header
256 collection buffer
------
260 total per product buffer
22 product variables
27 sub-task tss
------
309 allocation for 1st buffer
27 task tss (at prod task creation)
------
336 Total allocation for 1-buffer product
260 allocation for 2nd buffer
------
596 Total allocation for 2-buffer product
DATA COLLECTION
Because this file was adapted from a more elaborate science
product file, the functions include some unnecessary but
harmless parameterization for counter interval, spin angle, etc.
TLM FORMAT SYNCHRONIZATION
The FGM component on which the TLM format is re-sync'ed
is the 9th after the format pulse. Such offset (stored
in the constant Tlm_Hr_Fgm) has been chosen because in
both Hi and Low TLM table the ICI TLM activity around
such B component is relatively quite.
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