HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 66

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

MODE COMMAND PROCESSING
GENERAL CONSIDERATIONS
The device provides decoding for all mode code
combinations, consistent with MIL-STD-1553B
requirements. Several mode command options are
provided to suit any application requirement:
In Configuration Register 1, the option bit UMCINV
(Undefined Mode Codes Invalid) globally defines whether
undefined mode code commands are treated as valid
(default) or invalid commands. This bit applies only to the
following 22 mode code commands that are undefined in
MIL-STD-1553B:
If the UMCINV bit is low (default after
mode code commands are considered valid and RT
response is based on individual mode command settings
in the Illegalization Table: If the command’s table bit equals
0, the mode command is legal; the RT responds “in form”
and updates status. If the command’s table bit equals 1 the
mode command is illegal, the RT asserts Message Error
status and (if non-broadcast) transmits only its Status
Word without associated data word. The table below
describes explicit terminal response for each mode code
value and command
settings.
If UMCINV is asserted, the 22 undefined mode code
commands are treated as invalid: There is no terminal
recognition of the command. No command response
occurs and status remains unchanged for the benefit of
following “transmit status” or “transmit last command”
mode commands.
If UMCINV is low, the
status of commands from the Illegalization Table. If the
terminal does not use illegal command detection, the
Illegalization Table should be left in its post-reset default
state, all values equal logic 0. In this case, the terminal
provides “in form” response to all valid commands. The
terminal responds with clear status and a transmitted
mode data word for mode commands 16-31 with
equals 1. Assigned data buffer locations can be initialized
to provide predictable “in form” responses for all transmit
mode codes 16-31. (If UMCINV is asserted, the terminal
will not respond or update status for received mode codes
17, 20 and 21 with
To use illegal command detection, the host modifies the
Illegalization Table to make illegal any combination
subaddress and mode code commands. This may include
undefined mode codes, reserved mode codes, and/or
mode codes not implemented in the application.
Mode Codes 0 through 15 with
Mode Codes16, 18 and19 with
Mode Codes 17, 20 and 21 with
T/
R
T/
= 1.)
R
device determines legal vs. illegal
bit state, based on various option
MR
T/
T/
T/
R
R
reset) undefined
R
bit = 0
bit = 0
bit = 1
HOLT INTEGRATED CIRCUITS
HI-6120, HI-6121
T/
R
bit
66
Note: Mode command MC0 “dynamic bus control”
cannot be implemented in the device since the HI-6120
cannot act as a Bus Controller.
bus control acceptance” status bit cannot be set in the
outgoing status word from this device.
MODE COMMAND INTERRUPTS
For mode commands, interrupt generation is programmed
by the top three bits in the descriptor table Control Word.
Notice that broadcast-transmit interrupts can be enabled
for mode code values in the range of 0 - 15, but broadcast-
transmit mode codes 16 - 31 are not allowed. When a
mode command is received and the IWA interrupt bit is
asserted in its descriptor Control Word, that command will
generate a host interrupt if the IWA bit is high in the
Interrupt Enable Register. The IWA bit is asserted in the
Pending Interrupt Register and the
output is asserted.
Before
Interrupt Log buffer, writing a new IIW Interrupt Information
Word and a new IAW Interrupt Address Word. The IWA
(interrupt when accessed) bit is asserted in the new IIW to
indicate interrupt type. The IAW contains the Descriptor
Table address for the mode command’s Control Word,
based on mode code value and command word
state. The host reads the IAW to determine the command
that caused the interrupt.
MODE COMMAND DATA WORDS
Mode commands having mode code values from 0 through
15 (decimal) do not have an associated data word. These
are received as Command Word only, never having a
contiguous data word. The terminal response to valid
mode commands 0-15 always consists of Status Word
only, assuming command was not broadcast.
Mode commands having mode code values from 16
through 31 (decimal) always have an associated data
word. When the command word
terminal receives a data word, contiguously following the
Command Word. When valid legal mode commands 16-
31 arrive with
transmitting its status word with a single data word.
When the SMCP option bit in Configuration register 1 is
zero, individual data words for mode codes 16-31 decimal
are stored in an indexed or ping-pong buffer assigned by
the mode command’s Descriptor Table entry. Circular
buffer methods are not available for mode code
commands.
When the SMCP option bit in Configuration register 1 is
asserted, individual data words for mode codes 16-31
decimal are stored within the Descriptor Table itself. This is
explained next.
INTMES
T/
interrupt assertion, the device updates the
R
bit equal to 1, the terminal responds by
Therefore, the “dynamic
T/
R
INTMES
bit equals 0, the
interrupt
T/
R
bit