hi-6131pqtf QuickLogic Corp, hi-6131pqtf Datasheet - Page 160

• Manufacturer Part Number: hi-6131pqtf
• Description: Mil-std-1553 / Mil-std-1760 3.3v Bc / Mt / Rt Multi-terminal Device
• Manufacturer: QuickLogic Corp

ing “transmit status” or “transmit last command” mode
commands.
When either RT-RT command word (with subaddress
field not equal to 0x0 or 0x1F) is addressed to the HI-
6130/21 terminal, but the other command word contains
subaddress 0x0 or 0x1F, the RT-RT command is not rec-
ognized as valid. There is no RT command response,
and no status updating for the benefit of following “trans-
mit status” or “transmit last command” mode commands.
An RT-RT command pair where Command Word 1 is
addressed to the HI-6130/21 terminal and Command
Word 2 is addressed to a different terminal is considered
an “RT-RT receive” command. When the message is
transacted, the device sets the RTRT bit in the Receive
Subaddress Message Information Word in the subad-
dress data buffer.
An RT-RT command pair where Command Word 2 is
solely addressed to the HI-6130/21 terminal (not RT31)
is considered an “RT-RT transmit” command. The Mes-
sage Information Word does not distinguish the RT to
RT transmit message from an ordinary RT to BC trans-
mit command.
19.2. Command Illegalization Table
The following pages describe various structures resid-
ing in the RAM shared between the host and HI-6130 or
HI-6131 command processing logic. The host initializes
these structures to control the terminal’s response to re-
ceived commands. The first structure described is the
command Illegalization Table used for “illegal command
detection”.
Illegal command detection is an optional process. When
illegal command detection is not used, the terminal “re-
sponds in form” to all valid commands: it sends Clear
Status and transacts the number of data words defined
in the received command. When illegal command detec-
tion is not used, the bus controller cannot tell whether
the command is legal or illegal, from the terminal’s trans-
mitted response.
If illegal command detection is used, the terminal re-
sponds differently when an illegal command is detected.
The terminal responds to illegal commands with “mes-
sage error” status, transmitting only status word. Data
word transmission is suppressed if the command type
inherently includes transmitted data words. The terminal
responds to each legal command with clear status and
transacts the number of data words defined in the type
of command received.
HOLT INTEGRATED CIRCUITS
HI-6130, HI-6131
160
For consistency, apply illegal command detection to all
illegal and unimplemented commands, and to all re-
served or undefined mode code commands, or “respond
in form” to all of these commands (illegal command de-
tection disabled) by leaving the Illegalization Table in the
all-cleared default state after MR master reset
The device uses a 256-word “Illegalization Table” in
shared RAM to distinguish between legal and illegal
commands. After the (MR) master reset input is negated,
HI-6130/21 performs internal self test including a shared
RAM test which leaves all memory locations fully reset.
Once self test is complete, the HI-6130/21 READY out-
put goes high to indicate HI-6130/21 readiness for host
initialization. At this point, all entries in the Illegalization
Table read logic 0, so by default, illegal command detec-
tion is not applied.
To apply illegal command detection, the host (or auto-
initialization) writes the Illegalization Table to set bits for
all illegal command combinations. This typically includes
any unimplemented subaddresses and/or word counts,
undefined mode commands, reserved mode commands
and any mode commands not implemented in the ter-
minal design. Host initialization of the table can be re-
placed by auto-initialization.
Once STEX is set in Configuration Register 1, terminal
execution begins. Each time a valid command is re-
ceived, a 1-bit entry (indexed using command word data
bits) is fetched from the Illegalization Table:
If fetched Illegalization Table bit equals logic 0, the
command is “legal”; the terminal responds “in form”,
transmitting clear status and transacting the number of
data words defined for the message type. Terminal sta-
tus is updated.
If fetched Illegalization Table bit equals logic 1, the
command is “illegal”; the terminal responds with status
word only, with Message Error bit set. No data words are
transmitted. Terminal status is updated.
When illegal command detection is not applied, all table
entries should read logic 0; the terminal responds “in
form” to all valid commands.
The illegalization scheme allows any subset of command
T/R bit, broadcast vs. non-broadcast status, subaddress
and word count (or mode code number), for a total of
4,096 legal/illegal command combinations. Commands
may be illegalized down to the word count level. For ex-
ample, 10-word receive commands to a given subad-
dress may be legal, while 9-word receive commands to
the same subaddress are illegal.
Broadcast receive commands are illegalized separately