Core1553BBC MIL-STD-1553B Bus Controller
Word Formats
There are only three types of words in a 1553B message: a command word (CW), a data word (DW), and a status word
(SW). Each 20-bit word consists of a 3-bit sync pattern, 16 bits of data, and a parity bit (Figure
5).
Bit
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
CW
Sync
5
RT Address
1
T/R
5
Sub-address
5
Word Count/Mode Code
1
P
DW
Sync
16
Data
1
P
SW
Sync
5
RT Address
1
Message Error
1
Instrumentation
1
Service Request
3
Reserved
1
1
1
Subsystem Flag
1
Dynamic Bus
Acceptance
1
Terminal Flag
1
Broadcast
Received
Figure 5 •
1553B Word Formats
I/O Signal Descriptions
Table 2 •
1553B Bus Interface
Name
BUSAINEN
BUSAINP
BUSAINN
BUSBINEN
BUSBINP
BUSBINN
BUSAOUTIN
BUSAOUTP
BUSAOUTN
BUSBOUTIN
BUSBOUTP
BUSBOUTN
Type
Out
In
In
Out
In
In
Out
Out
Out
Out
Out
Out
Description
Active high output that enables for the A receiver
Positive data input from the A receiver
Negative data input from the A receiver
Active high output that enables for the B receiver
Positive data input from the bus to the B receiver
Negative data input from the bus to the B receiver
Active high transmitter inhibit for the A transmitter
Positive data output to the bus A transmitter (is held high when no transmission)
Negative data output to the bus A transmitter (is held high when no transmission)
Active high transmitter inhibits the B transmitter
Positive data output to the bus B transmitter (is held high when no transmission)
Negative data output to the bus B transmitter (is held high when no transmission)
6
v4.0
Parity
Busy
ACTEL [ Actel Corporation ]
