CT2554 Aeroflex Circuit Technology, CT2554 Datasheet - Page 17

• Manufacturer Part Number: CT2554
• Description: Ct2553 / 2554 / 2555 / 2556 Advanced Integrated Mux Aim Hybrid For Mil-std-1553
• Manufacturer: Aeroflex Circuit Technology

Aeroflex Circuit Technology
CURRENT AREA B/A
T/R (from command word)
SUB-ADDRESS (command word)
RTU MESSAGE BLOCK TRANSFER SEQUENCE
RTU
automatically upon receipt of a valid command
word from the 1553 bus. A message transfer
takes the form of an RTU Start Of Message
(SOM) cycle followed by the 1553 Message
Transfer Cycle and an RTU End Of Message
(EOM) cycle (See Figure 22).
During the RTU SOM cycle, the CT2553 the
following actions:
1. Loads the 1553 command word.
2. Reads the current area Stack Pointer to get the
3. Stores an SOM flag into the Block Status Word
4. Writes the Time Tag value into the the
5. Stores the Command Word received.
6. Reads the associated Data Block Address from
The MESSAGE TRANSFER CYCLE refers to the
actual transfer of the 1553 message under control
of the CT2553. The CT2553 transfers data to and
from the memory on a word-by-word basis.
Upon completion of the message transfer, the
CT2553 executes an RTU End Of Message
(EOM) cycle during which the CT2553:
1. Generates an EOM or Error interrupt (if
2. Updates the Block Status Word: clears SOM,
3. Writes the Time Tag value into the Descriptor
4. Increments the Stack Pointer by 4.
address of the current Descriptor Stack Entry
(DSE).
to indicate a transfer in progress.
Descriptor Stack.
the (current area) Look-Up Table.
enabled).
sets EOM, and any appropriate error bits.
Stack.
Figure 20 – RTU Look-Up Address
15
0 0 0 0 0 0 0 1
message
transfer
7 6 5 4 3 2 1 0
1
operations
begin
17
T/R SUBADD
0
1
1
0
0
RECEIVED COMMAND WORDS
Figure 22 – RTU Message Transfer
Figure 21 – Look-Up Table Example
00000
00001
00010
11110
11111
64 LOCATIONS
GENERATE EOM INTERRUPT AND
UPDATE BLOCK STATUS WORD
READ LOOK-UP TABLE USING
ERROR INTERRUPT IF ERROR
UPDATE DESCRIPTOR STACK
INCREMENT STACK POINTER
BLOCK STATUS WORD, TIME
T/R SUBADDRESS CURRENT
TRANSFER DATA TO/FROM
TAG AND COMMAND WORD
1553 INTERFACE DEVICE
1553 COMMAND WORD
READ STACK POINTER
COUNT
MESSAGE COMPLETE
CONDITION DETECTED
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
WORD
WAIT FOR NEXT
1553 COMMAND
AND TIME TAG
Operation
AREA BIT B/A
SCDCT2553 REV B 8/6/99 Plainview NY [phone]
RECEIVED
BY FOUR
ADDRESS
?
TABLE (A)
LOOK-UP
YES
017E
0140
0141
0142
017F
*
*
*
USER DEFINED
USER DEFINED
USER DEFINED
USER DEFINED
USER DEFINED
DATA BLOCK
DATA BLOCK
NO