HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 68

• Manufacturer Part Number: HI-6121PQMF
• Description: MIL-STD-1553 Remote Terminal ICs
• Manufacturer: HOLTIC [Holt Integrated Circuits]

MODE COMMAND PROCESSING, Cont.
STANDARD MODE COMMAND PROCESSING
Data buffer options for mode commands differ from buffer
options for subaddress commands. Mode commands can
use ping-pong buffering or indexed buffering. When mode
commands use indexed buffers, “single message mode”
(INDX = 0) is recommended. When using indexed or ping-
pong buffers for mode commands:
SIMPLIFIED MODE COMMAND PROCESSING
Mode commands have a buffer alternative that is
unavailable for subaddress commands. The SMCP bit in
Configuration Register 1 selects
Command Processing
mode commands. When the SMCP bit is high, mode
command descriptor blocks (in the Descriptor Table) do
not contain data pointers to reserved buffers elsewhere in
the shared RAM. Instead, each 4-word descriptor block
itself contains the message information word, the time-tag
word and the data from the most recent occurrence of each
mode command:
Descriptor Word 1 contains the receive or transmit mode
command Control Word. When SMCP is used, just two
Control Word bits are used: DBAC (descriptor block
accessed) and BCAST (broadcast).
For mode commands without associated data word
(mode codes 0-15 decimal), only the Message
Information and Time-Tag words are updated in the
mode command’s assigned data buffer in RAM.
For mode commands 16-31 (decimal) that receive a
data word, indexed and ping-pong buffer methods
copy the received mode data word to the mode
command’s assigned data buffer in shared RAM, after
the message is transacted. The Message Information
and Time-Tag words are also updated.
For most mode commands 16-31 (decimal) that
transmit a data word, the device reads the data word
for transmit from the buffer location assigned in the
Descriptor Table. Exceptions occur for MC18 “transmit
last command” and for MC19 “transmit BIT word.” The
MC18 data word is automatically provided by the
device, based on recent command transactions. The
MC19 data word comes from register 0x14 or 0x15,
depending on the state of the ALTBITW option in
Configuration Register 2. For both MC18 and MC19,
the transmitted data word is automatically recorded in
the mode command’s assigned data buffer in RAM,
after message completion. The Message Information
and Time-Tag words are also updated.
Descriptor Word 1
Descriptor Word 2
Descriptor Word 3
Descriptor Word 4
, a global option applying to all
Mode command Control Word.
Message Information Word.
Time-Tag Word.
Mode Data Word.
Simplified Mode
HOLT INTEGRATED CIRCUITS
HI-6120, HI-6121
68
When SMCP is enabled, the host need not initialize the
mode code command segments in the Descriptor
Table.
selected, the host does not write Descriptor Words 2-3 in
the Descriptor Table entries for mode commands. For
mode code values 0 to 15 decimal, the Descriptor Word 4
serves no function because these mode codes do not have
an associated data word. For transmit mode code values
16 to 31, the host may initialize Descriptor Word 4. The
default transmit value is 0x0000. Mode command MC16
“transmit vector word” is one of the three defined mode
commands that transmit a data word: MC16, MC18 and
MC19. Its Descriptor Word 4 should be initialized if a value
other than 0x0000 is needed.
discussed below.
Table 3 shows terminal response to all possible
subaddress and mode code command combinations. The
table summarizes terminal response for the full range of
message conditions, including errors, incomplete
messages, etc. The table explicitly describes terminal
response and impact on terminal Status Word, Descriptor
Control Words and data buffer Message Information
Words. The table includes effects for all pertinent setup
options and identifies all interrupt options available.
text blocks
Status responses when the terminal is not using “illegal
command detection”.
For mode commands without associated data word
(mode codes 0-15 decimal), Simplified Mode
Command Processing updates the Message
Information and Time-Tag words in Descriptor Words 2
and 3, and Descriptor Word 1 (bits 9,11). For these
commands, SMCP does not update Descriptor Word
4, which may be non-zero if written earlier by the host.
For receive mode commands 16-31 (decimal) that
receive a data word, Simplified Mode Command
Processing copies the received mode data word to
Descriptor Word 4. The Message Information and
Time-Tag words in Descriptor Words 2 and 3, and
Descriptor Word 1 (bits 9, 11) are also updated.
For most transmit mode codes 16-31 (decimal), the
device reads the data word for transmission from each
command’s Descriptor Word 4. Exceptions occur for
MC18 “transmit last command” and for MC19 “transmit
built-in test word”. The MC18 data word is
automatically provided, based on the last command
transacted. The MC19 data word comes from register
0x14 or 0x15, depending on the state of the ALTBITW
option in Configuration Register 2. For MC18 and
MC19, the transmitted data value is automatically
copied to the mode command’s Descriptor Word 4
after message completion. The Message Information
and Time-Tag words in Descriptor Words 2 and 3, and
Descriptor Word 1 (bits 9, 11) are also updated.
When Simplified Mode Command Processing is
indicate error-free messages or “in form” Clear
————————————
MC18 and MC19 are
Bold