HI-6136_16 Datasheet, PDF (118/206 Pages) Holt Integrated Circuits – Compact Multi-Terminal Device with SPI Host Interface

HI-6136
Bit No.
8
7,6
5
4-0
Mnemonic
ILCMD
-----
BUSID
MC4:0
Function
Illegal Command Received.
This bit is asserted when the Illegalization Table bit corresponding to the received com-
mand equals one. The Illegalization Table should only contain nonzero values when “il-
legal command detection” is being applied. See Section 14.2 for further information.
Not Used.
Bus Identification.
If this bit equals zero, message was transacted on Bus A. If bit equals one, it was trans-
acted on Bus B.
Mode Code.
This 5-bit field contains the mode code extracted from the command word.
15.2.2. Transmit Mode Command
The transmit mode command data structure contains a Message Information Word, a Time-Tag word and may contain
one Data Word. For mode commands with associated data word (mode codes 16-31 decimal) the host is responsible
for loading the Mode Command Data Table before transmit mode commands are received (e.g., Transmit Vector Word
mode code). Two mode codes have internally generated data words: MC18 “Transmit Last Command” and MC19
“Transmit BIT Word”. For these, the device automatically transmits the data word then copies the transmitted data
value to the stored data structure.
Here is an example data structure for a transmit mode command with data (mode code values 0x10 through 0x1F).
This applies to MC16 “Transmit Vector Word”. Notice that the data pointer points to the data structure starting address,
not the mode data word. The data pointer is located in the transmit mode command’s Descriptor Block, fully described
later:
Data Buffer
Hex Address
Word Description
Word is Written By ...
Data pointer equals 0x1500 → 0x1500
0x1501
0x1502
Message Information Word
Time-Tag Word
Mode Data Word
Device, after message completion
““
“
“
Host, prior to terminal’s data transmit
(except MC18, MC19 are written by
the device after completion)
Three transmit mode commands with data are not defined under MIL-STD-1553B. These are MC17, MC20 and
MC21 (mode codes 0x11, 0x14 and 0x15 respectively). However the device responds “in form” if illegal command
detection is not used (corresponding bits in Illegalization Table are logic 0) and the UMCINV bit in the “Remote
Terminal Configuration Register (0x0017)” is logic 0.
For mode code commands without data, the data structure contains only the Message Information Word and Time-Tag
Word. Here is an example data structure for a transmit mode command without data (mode code values 0x00 through
0x0F). Again, the data pointer points to the data structure starting address. The data pointer is located in the transmit
mode command’s Descriptor Block, fully described later:
HOLT INTEGRATED CIRCUITS
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