CT2553-PCB Aeroflex Circuit Technology, CT2553-PCB Datasheet - Page 18

• Manufacturer Part Number: CT2553-PCB
• Description: Advanced Integrated Mux Aim Hybrid For Mil-std-1553 / Sae-as15531 In Pcb Style
• Manufacturer: Aeroflex Circuit Technology

ADDITIONAL FEATURES.
Word flags can be programmed via the appropriate
Configuration Register bits. In addition, setting Interrupt
Mask Register bits will result in a low pulse on the
Interrupt (
respective error or end of message condition. (See
Configuration Register and Interrupt Register sections.)
THIS RT: Each command appearing on either 1553 Bus
is decoded and tested for Manchester/protocol errors. If
the CT2553-PCB receives a valid command word
containing
RTAD0-RTAD4 inputs (pins 10, 9, 50, 49, and 11,
respectively),
signal can be used to identify specific 1553 commands.
This signal is also active in the BC mode.
Command Illegalization (Optional). The CT2553-PCB
has the capability to illegalize MIL-STD-1553 mode
commands. In addition, valid non-mode commands can
be illegalized based upon the Command Word
subaddress field. An illegal command is identified by
driving the Illegal Command,
low. The CT2553-PCB multiplexes the Word Count and
Subaddress fields (pins SA/MC0 - SA/MC4).
The CT2553-PCB responds to illegalized commands by
transmitting its Status Word with the Message Error bit
set. No data words are transmitted; received words,
however, are placed in the shared RAM locations
indicated by the current area Look-Up Table.
SA/MC0-4, T/R
SCDCT2553PCB Rev A Preliminary 7/13/06
ILLCMD
LMC
SYMBOL
FIGURE 23 – MODE COMMAND/SUB-ADDRESS ILLEGALIZATION TIMING
INT
a
t1
THIS-RT
) pin with each occurrence of the
RTU
(pin 55) will be pulsed low. This
address
DESCRIPTION
MODE COMMAND ILLEGALIZATION TIMING
LMC to ILLCMD latch
ILLCMD
equivalent
Four 1553 Status
(pin 12) input
t1
to
the
LATCHED UNTIL NEXT VALID COMMAND WORD RECEIVED
VALID UNTIL NEXT VALID COMMAND WORD RECEIVED
18
Upon receipt of a valid mode command, the
CT2553-PCB will output the Command Word-Word
Count field and set the Latched Mode Command (LMC)
output to a logic 1. Upon receipt of a valid non-mode
command, the CT2553-PCB will output the Command
Word-Subaddress field and set the Latched Mode
Command (LMC) output to a logic 0.
An external PROM can be used for command
illegalization by decoding the word count/subaddress,
LMC and Broadcast Received (
driving
BUSY BIT.
Configuration Register, the CT2553-PCB will respond
with a Status Word with the BUSY bit set. In addition,
no data words will be transferred from the shared RAM
as indicated by the corresponding value in the current
area Look-Up Table. The CT2553-PCB will transfer
data associated with a Receive Command into memory
but will not transmit data out onto the MIL-STD-1553
bus when busy upon receipt of a Transmit Command.
ILLCMD
If the user asserts the BUSY bit low in the
low where appropriate (See Figure 23).
MIN
250
MAX
-
BCSTRCV
UNITS
Aeroflex Plainview
ns
) bits and