HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 28

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

COMMAND RESPONSES, Cont.
commands. For example, command MC0 (with
probably unimplemented because the HI-6120 does not
have provisions for accepting “dynamic bus control”.
The important point is that “illegal command detection”
should be universally applied (or not applied) when setting
up a HI-6120 Remote Terminal application. Here are the
two options:
Not using Illegal command detection.
Illegalization Table is left in its default state (all locations
equal to MR post-reset 0x0000). The terminal responds “in
form” to all valid commands, whether legal or illegal.
Using illegal command detection.
Illegalization Table is initialized by the host to implement
“illegal command detection”. The host sets bits for all illegal
commands. This generally includes the reserved and
unimplemented mode commands, unimplemented
subaddresses (or specific word counts,
and/or broadcast vs. non-broadcast status within
subaddresses). Treatment for the undefined mode
commands depends on UMCINV bit.
The host defines terminal response for all individual
commands by initializing the Descriptor Table, fully
described later. At this point, a few comments about the
Descriptor Table are appropriate.
The command SA (subaddress) field has a range of 0 to 31
(0x1F). When SA is in the range 1 to 30 (0x1E), the
command is a transmit or receive “subaddress command”.
The number of data words transmitted or received is
expressed in the low order 5 bits. When SA equals 0 or 31
(0x1F) the command is a mode command and the mode
code value is expressed in the low order 5 bits.
For each subaddress, separate table “descriptor blocks”
for transmit and receive commands permit different data
buffering to be applied. The host initializes the table so
each transmit-subaddress and each receive-subaddress
uses one of four methods for storing message data. During
table initialization, memory is allocated in shared RAM for
storing message data according to the application
requirements. Each transmit-subaddress and receive-
subaddress has one or more data pointers (depending on
buffer method) addressing its reserved data buffer(s).
Each mode command also has its own table “descriptor
block”. Mode commands have either one data word or no
associated data words. Descriptor words used as data
pointers by “subaddress commands” are instead used for
direct storage of transacted mode data words. Mode
commands that transmit or receive mode data words have
a dedicated storage address range in shared RAM,
eliminating the need for descriptor table data pointers.
T/
The HI-6120
HOLT INTEGRATED CIRCUITS
The HI-6120
R
T/
bit states,
R
HI-6120, HI-6121
= 1) is
28
Each mode command with mode data word has its own
fixed address for data storage. This includes reserved
mode codes with data word. Thus the HI-6120 can
respond consistently for all mode commands; transmitted
data values for “in form” responses (when “illegal
command detection” is not used) can be predetermined,
even for the reserved mode commands.
RT to RT Commands.
allows for data word transmission from a specified
transmitting terminal to a different receiving terminal.
When broadcast commands are allowed, data
transmission can be addressed to the broadcast terminal
address, RT31. If broadcast is allowed, the host should
initialize the BCSTINV (broadcast invalid) bit in
Configuration Register 1 to logic 0.
All RT to RT commands are characterized by a pair of
contiguous command words: Command Word 1 is a
receive command addressed to the intended receiving
terminal, then Command Word 2 is a transmit command
addressed to a single transmitting terminal. Command
Word 2 cannot be broadcast address RT31. The HI-6120
automatically detects and handles RT to RT commands,
except when either command word contains a subaddress
field equal to 0x0 or 0x1F. Either subaddress value
indicates a mode code command; the device treats RT to
RT commands with mode code as invalid. If either RT-RT
command word is addressed to the HI-6120 terminal but
contains subaddress 0x0 or 0x1F, t
recognized; there is no RT command response, and no
status updating for the benefit of following “transmit status”
or “transmit last command” mode commands.
When either RT-RT command word
not equal to 0x0 or 0x1F)
terminal, but the other command word contains
subaddress 0x0 or 0x1F,
recognized as valid. There is no RT command response,
and no status updating for the benefit of following “transmit
status” or “transmit last command” mode commands.
An RT-RT command pair where Command Word 1 is
addressed to the HI-6120 terminal and Command Word 2
is addressed to a different terminal is considered an “RT-
RT receive” command. W
t
Message Information Word in the subaddress data buffer.
An RT-RT command pair where Command Word 2 is
solely addressed to the HI-6120 terminal (not RT31) is
considered an “RT-RT transmit” command. The Message
Information Word does
transmit message from an ordinary RT to BC transmit
command.
he device sets the RTRT bit in the Receive Subaddress
hen the message is transacted,
not
The MIL-STD-1553 standard
the RT-RT command is not
is addressed to the HI-6120
distinguish the RT to RT
(with subaddress field
he command is not