HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 60

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

CIRCULAR BUFFER MODE 1, Cont.
descriptor Control Word IXEQZ bit is asserted (and if the
Interrupt Enable Register IXEQZ bit is asserted) the device
indicates “transmit buffer empty” by asserting the
interrupt output.
Circular Buffer Mode 1 does not support NOTICE2
segregation of broadcast data, even when the NOTICE2
bit equals 1 in Configuration Register 1. Data from
broadcast and non-broadcast receive commands is stored
in the same buffer. The BCAST bit in the Message
Information Word reflects broadcast or non-broadcast
status for each stored message. If broadcast messages
are not expected during data block transmission, the host
can illegalize broadcast commands for the subaddress.
Broadcast illegalization can be done either permanently, or
only when data block transmission is scheduled.
For transmit subaddresses using Circular Buffer Mode 1,
occurrences of broadcast-transmit commands to RT31 do
Memory Address for the Applicable
Subaddress Block is Derived From
Descriptor block is initialized so Current Address equals buffer Start Address. After each successful message
transaction, Current Address is adjusted to point past last data word accessed. If adjusted Current Address points
past End Address, the Current Address is reinitialized to match Start Address and an optional interrupt is
generated to notify host that the pre-determined data block was fully transacted.
the Decoded Command Word
Figure 15. Illustration of Circular Buffer Mode 1
HOLT INTEGRATED CIRCUITS
Descriptor Block
Current Address
for Subaddress
Start Address
Control Word
End Address
INTMES
Increasing
HI-6120, HI-6121
Address
Memory
60
First Message
Last Message
in Data Block
in Data Block
not result in bus transmission. However these messages
update the Message Information Word addressed by the
Current Address (CA) pointer (and following Time-Tag
Word)
unchanged
subaddress, whether broadcast or not, overwrites the
Message Information and Time-Tag Word locations written
by the previous broadcast transmit command.
Message
Current
but afterwards, the CA pointer remains
. The next transmit command to the same
Message Info Word
Message Info Word
Message Info Word
More Messages
More Messages
Time-Tag Word
Time-Tag Word
Time-Tag Word
Data Word(s)
in Data Block
Data Word(s)
in Data Block
Data Word(s)
Data Word N
Data Word N
Data Word N
Subaddress
Data Word 1
Data Word 1
Data Word 1
Data Buffer
Assigned
Circular
End
Address
Current
Address
Start
Address