HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 56

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

INDEXED DATA BUFFERING
INDEXED DATA BUFFER MODE
Also called “single buffer mode”, indexed buffering is one
method for storing message and time-tag information and
data associated with messages. Buffer mode is selected
for each subaddress or mode code in the Descriptor Table
Control Words. Indexed mode is enabled when Control
Word PPEN, CIR1EN and CIR2EN bits are all zero.
When a subaddress or mode command uses the indexed
data buffer mode, its 4-word descriptor block in the
Descriptor Table is defined as follows:
Upon successful message completion, if non-zero the INDX count in Descriptor Word 3 is decremented.
If decremented result is non-zero, Data Pointer A is adjusted so next message is stored above just-completed message.
If decremented INDX is zero, Data Pointer A remains static, and IXEQZ interrupt occurs if enabled in Control Word.
Descriptor Word 1
Descriptor Word 2
Descriptor Word 3
Descriptor Word 4
Message Info Word
Memory Address for the Applicable
Memory Address for the Applicable
Subaddress Block is Derived From
Subaddress Block is Derived From
Time-Tag Word
for Broadcast
Buffer Space
Data Word(s)
Subaddress
Data Word N
Data Word 1
(Optional)
the Decoded Command Word
the Decoded Command Word
Control Word
Data Pointer A
INDX Index Word
Broadcast Data Pointer
Figure 13. Illustration of Single-Buffer Indexed Mode
if NOTICE2
Broadcast
is asserted
Message
HOLT INTEGRATED CIRCUITS
HI-6120, HI-6121
B’cast Data Pointer
INDX Index Count
Descriptor Block
for Subaddress
Data Pointer A
Control Word
Increasing
Memory
Address
56
If Descriptor Word 1 is stored at memory address N,
Descriptor Word 2 is stored at address N+1, and the other
two words are stored at addresses N+2 and N+3.
As the name implies, all message information and data is
stored in a single buffer, indexed by descriptor word Data
Pointer A. The descriptor Control Word DPB bit is “don’t
care”. The host initializes the desired message count in
descriptor INDX word. During message processing, the
device retrieves or stores data words from the address
specified by descriptor Data Pointer A, automatically
incrementing the pointer address as words are read or
stored. Data Pointer A is updated during command post-
processing with the current buffer address unless the
message index count in descriptor INDX (word 3 of
Preceding
Message
Message
Message
Current
Next
Message Info Word
Message Info Word
Message Info Word
Time-Tag Word
Time-Tag Word
Time-Tag Word
Buffer Space
Data Word(s)
Data Word(s)
Data Word(s)
Data Word N
Data Word N
Data Word N
Subaddress
Data Word 1
Data Word 1
Data Word 1
Assigned