CT2554 Aeroflex Circuit Technology, CT2554 Datasheet - Page 8

• 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
EOM
SOM
CHB/CHA
(RTU ONLY)
ERROR FLAG
The contents of the fourth word of the stack entry
depends upon the 1553 operating mode selected.
In BC mode, It contains the address of the
associated 1553 message (Data Block). In RTU
mode, it contains the complete (received) 1553
Command Word.
Note: In BC operation, the CT2553 always writes the BSW to RAM with
Bit-13. CHB/CHA toggles as per the message control word setting.
EOM
SOM
CHB/CHA
ERROR
FLAG
STATUS SET Set in BC mode to indicate that a status
FORMAT
ERROR
RESPONSE
TIMEOUT
BIT NAME
LOOP
TEST FAIL
Figure 8 – Descriptor Stack - Block Status
15
Set at the completion of a message
transfer regardless of whether any errors
were detected.
Set at the beginning of a message transfer
and Reset upon completion of the transfer.
Set in RTU mode to indicate whether the
message was received on 1553 bus A or
bus B. Toggles to indicate channel, in BC
mode.
Indicates that an error was detected within
the message transfer. The specific error
condition(s) are identified in bits 8-11.
flag bit was set within the received RTU
Status Word or that the RTU address did
not match the associated Command. Set
in BC mode when the message error bit is
set within the received RTU Status Word.
Also set in RTU mode (RT-RT transfer;
CT2553 is acting as the receiving RT)
when the transmitting RTU Status Word
contains an incorrect address. Also, set in
BC or RTU mode if the message violates
MIL-STD-1553 (parity, Manchester, sync
bit count, non-contiguous data or word
count errors).
Set in BC mode if the addressed RTU did
not respond within 14µs. Also set when
acting as a receiving RT (RT-RT transfer) if
the transmitting RT does not respond in
the specified 1553 response time.
Set when the CT2553 does not pass the
Loop Test. See Self Test paragraph.
Word
8 7
LOOP TEST FAIL
RESPONSE TIME OUT (BC ONLY)
FORMAT ERROR
STATUS SET (BC ONLY)
1 1 1 1 1 1 1 1
DEFINITION
0
8
STACK POINTER. A STACK POINTER (SP) is
maintained at a specified location in shared RAM
for each Descriptor Stack (SP-A: 0100H; SP-B:
0104H). Each Stack Pointer must be initialized by
the CPU to point to the Descriptor Stack Entry to
be used for the first MIL-STD-1553 transmission.
The current area SP is automatically incremented
by four following each message transfer thereby
always pointing to the next Block Status Word.
LOOK-UP TABLE (RTU). A data block address
Look-Up Table is used to indicate the data blocks
to be used for individual commands. Look-Up is
based upon the T/R (transmit/receive) and
Subaddress bits of the received 1553 Command
Word. See RTU Operation for detailed operation;
two tables are provided for double buffering in the
RTU mode.
MULTIPLE
areas of shared RAM can be used to store
additional stacks, tables, data blocks and/or user
(non 1553-related) data. In this way, multiple data
blocks (RTU) or messages (BC) can be stored for
later use: simply update respective pointers and
initiate the appropriate start conditions. (BC mode
requires SP, message block address and message
count updating while in RTU mode, the SP and
Look-Up Table entry must be updated).
CT2553 REGISTERS
The CT2553 is controlled through the use of three
internal
Configuration Register and a Start/Reset Register.
In addition, the CT2553 can access up to four
external, user supplied registers (See Table 2).
Possible external register applications include:
CPU Time Tag storage and RTU Address
assignment (See Figures 9 and 10).
Note: The Stack Pointer is maintained internally using an
8-BIT REGISTER for the HIGH BYTE and an 8-BIT
COUNTER for the LOW BYTE. The high byte remains
constant (user value) while the low byte will wrap around
from FF(H) to 00(H). For example: a current Stack Pointer
value of 00 FF(H) will increment to 00 00(H) and not
01 00 (H).
registers:
BUFFERING
SCDCT2553 REV B 8/6/99 Plainview NY [phone]
Interrupt
(BC/RTU).
Mask
Register,
Unused