HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 61

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

CIRCULAR BUFFER MODE 1, Cont.
Unlike Indexed mode, Data Block completion is based on Buffer Full / Buffer Empty, not number of messages.
Buffer size was purposely sized to yield remaining capacity after 2 full-count messages, to illustrate device behavior.
The circular buffer should have a 33-word pad beyond its End Address to deal with buffer overrun without data loss.
Increasing
Address
Memory
Buffer Start
Buffer End
Address
Address
Receive Subaddress
Descriptor Block
Data Words 2-31
Time-Tag Word 3
Data Words 2-31
Time-Tag Word 2
Data Words 2-31
Time-Tag Word 1
Current Address
Msg Info Word 3
Msg Info Word 2
Msg Info Word 1
Figure 16. Circular Buffer Mode 1 Example for a Receive Subaddress
Start Address
Data Word 32
Data Word 32
Data Word 32
Control Word
End Address
Data Word 1
Data Word 1
Data Word 1
for a
HOLT INTEGRATED CIRCUITS
HI-6120, HI-6121
0x0565
0x0547 - 0x0564
0x0546
0x0545
0x0544
0x0543
0x0525 - 0x0542
0x0524
0x0523
0x0522
0x0521
0x0503 - 0x0520
0x0502
0x0501
0x0500
RAM
Address
End Address = 0x0546
Current Address = 0x0500
Start address = 0x0500
Control Word = 0x8001
Initialized Descriptor Values
61
(1 + Data Word 32 address) < End Address.
Device updates Current Address to 0x0544.
(1 + Data Word 32 address) < End Address.
Device updates Current Address to 0x0522.
Receive Message #1
32 Data Words
Unless serviced by host
after Message #3 Interrupt,
Message #4 will overwrite
buffer, starting at 0x0500
(1 + Data Word 32 address)
Device updates Current Address to
equal the Start Address, 0x0500.
IXEQZ interrupt is generated.
Receive Message #3
32 Data Words
Receive Message #2
32 Data Words
Buffer end address in RAM
Buffer current address in RAM
Buffer start address in RAM
Circular Mode 1, IXEQZ Interrupt
³
End Address.