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.