CT2565 Datasheet, PDF (19/31 Pages) Aeroflex Circuit Technology – CT2565 Bus Controller, Remote Terminal and BUS Monitor FOR MIL-STD-1553B

MT Operation
In the MT mode, the CT2565 captures all valid
transmissions on both channels of the 1553 bus, allowing
the user to monitor bus activity. Each word is transferred to
the subsystem along with an identification for interpretation
of the 1553 data stream.
MT Initialization
Initialize the CT2565 for MT operation per Table 2. The
CT2565 will remain in an idle state until BCSTART (pin 41)
is pulsed low. Figure 21 illustrates MT operation.
Valid words received by the CT2565 are transferred to the
subsystem along with an identification Word by a single
DMA handshake with two memory-write operations shown
in Figure 22, MT Transfer Timing. Since the decoder will
reject words based on sync field errors and/or errors in the
first 2 non-sync bits, these words will not be processed
further (i.e., the subsystem will receive no indication of the
receipt of this word).
15
87
0
GAP TIME
WORD TRANSFER
LOGIC "1"
LOGIC "1"
VALID WORD
COMMAND SYNC
CH A/B
WORD GAP
SET TO "0"
NAME
Definition
GAP TIME
NODT low time. 2MHz Clock
allows 500ns increments to
128µs (remains static at FF on
overflow).
WORD TRANSFER
Logic "1" indicates successful
transfer to subsystem.
WORD TRANSFERRED
Indicates successful transfer
(See bit 7)
VALID WORD
Reset (1) indicates Manchester
error, Parity error, Low Bit Count
and/or Status sync field.
COMMAND SYNC
Logic "1" indicates Command or
Status sync field. Logic "0"
indicates data sync.
CHAN A/B
Logic "1" if word received on
1553 bus Channel B.
WORD GAP
Set (0) if current word was
received at least 2µs after
receipt of previous word (parity
to mid-sync).
Note: Subsystem should clear entire memory prior to start of MT
operation.
Figure 20 – Identification Word
Aeroflex Circuit Technology
19
START
INITIALIZATION
(START-UP ONLY)
START MT OPERATION
1553 BUS
ACTIVITY
DECODER CHECK
SYNC + 2 BITS
ERYREOSR
YES
?
NO
NODT LOW
DMA
MEMORY WRITE
1553 INPUT
INCREMENT MEM ADDR
MEMORY WRITE
IDENTIFICATION WORD
INCREMENT MEM ADDR
Notes:
(1) Steps marked with " _ _ _" indicates operation is
transparent to user.
(2) Steps marked with " ___" indicates user interaction
required.
Figure 21 – MT Operation Flow Chart
SCDCT2565 REV B 8/10/99 Plainview NY [phone]