hi-6110 Holt Integrated Circuits, Inc., hi-6110 Datasheet - Page 26

• Manufacturer Part Number: hi-6110
• Description: Bc / Rt / Mt Message Processor
• Manufacturer: Holt Integrated Circuits, Inc.

BUS MONITOR OPERATION (MT mode)
When configured as a Bus Monitor with no assigned RT
address, the HI-6110 continuously monitors the selected
MIL-STD-1553 bus and passively captures all bus traffic.
The HI-6110 never transmits information onto the bus.
When a Command Word is received, a validation check is
performed. If the Command Word contains no errors, the
RFLAG
complete message in its internal registers and Receiver
Data FIFO as appropriate.
If the valid Command Word was received on Bus A, the
RCVA signal goes high to notify the host that a new
message has commenced. The RCVB pin is asserted when
the valid Command Word arrived on Bus B.
The Command Word may be read from the Command Word
1 register, or the Message register can be read to directly
learn the type of command received.
If the monitored MIL-STD-1553 system utilizes RT-RT
commands, special precautions arise if superseding
commands may occur on the same bus. Consider this
unusual sequence of events:
MSB
MSB
MSB
COMMAND WORD 1 REGISTER (Read only) Read Address: 0000
COMMAND WORD 2 REGISTER (Read only) Read Address: 0001
RECEIVE MODE DATA REGISTER (Read only) Read Address: 0010
a) an RT-RT command pair is received. Command
Word 1 addresses the receiving RT (called "RxRT" in
this example) and Command Word 2 addresses the
transmitting RT (called "TxRT").
b) following the RT-RT command pair, the Bus Monitor
normally expects to see the TxRT Status Word followed
by the commanded number of data words. Instead, the
Bus Controller issues a superseding command to the
RxRT; the word following the RT-RT command pair has
command sync and is addressed to the RxRT (not the
TxRT).
15 14 13 12 11 10 9
15 14 13 12 11 10 9
15 14 13 12 11 10 9
pin goes low and the HI-6110 MT captures the
RT Address
RT Address
Mode Data Word 15:0
Subaddress /
Subaddress /
8
8
8
Mode
Mode
7
7
7
6
6
6
5
5
5
HI-6110 (BUS MONITOR MODE)
Data Word Count /
Data Word Count /
4
4
4
HOLT INTEGRATED CIRCUITS
Mode Code
Mode Code
3
3
3
2
2
2
1
1
1
MT OPERATION
0
0
0
LSB
LSB
LSB
26
For all commands except RT to RT, the Command Word 1
register contains the last valid Command Word received.
When RCV is asserted, if Message Register bit 2 or bit 8 is set,
the new message is RT to RT. The Command Word 1 register
holds the first (receive) command and the Command Word 2
Register holds the second (transmit) command.
T
command word
above for Command Word 1.)
Whenever RCV is asserted, RT-RT messages can be
detected by checking Message Register bits 2 and 8.
The read-only Receive Mode Data Register holds the Mode
Code Data Word received during a Mode Code with Data
Word (Receive) Command.
he Command Word 2 register contains the second (transmit)
The HI-6110 bus monitor treats the unexpected word as a
superseding command for the RxRT. Monitor processing
stops for the RT-RT message. The new command word is
stored in the Command Word 1 register and the HI-6110
stores message results for the new superseding message
in the appropriate registers. To assure this treatment for the
RxRT superseding command, the host should apply Master
Reset after completion of any fulfilled RT-RT command,
following all necessary register operations by the host. This
reset should be performed before reception of the next RT-
RT command that might be followed by a superseding
command to the RxRT occuring before the TxRT response.
The above paragraph describes an unlikely occurrence
because the BC's transmission of a superseding command
is likely to collide on the bus with the TxRT response to the
original RT-RT command.
BUS MONITOR OPERATION (MT/RT mode)
When configured as a Monitor with assigned RT address,
the HI-6110 responds to all commands that match its hard-
wired RT address as described in the RT section of this data
sheet. All other bus traffic is monitored as described in this
MT section.
from the last RT-RT message.
(See note