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
5
1
5
5
1
P
Sync
Sync
RT Address
T/R
Sub-address
Word Count/Mode Code
DW
SW
16
1
P
Data
5
1
1
1
3
1
1
1
1
1
1
Sync
RT Address
Reserved
Figure 5 • 1553B Word Formats
I/O Signal Descriptions
Table 2 • 1553B Bus Interface
Name
Type
Out
In
Description
BUSAINEN
BUSAINP
Active high output that enables for the A receiver
Positive data input from the A receiver
BUSAINN
BUSBINEN
BUSBINP
In
Negative data input from the A receiver
Out
In
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
BUSBINN
In
BUSAOUTIN
BUSAOUTP
BUSAOUTN
BUSBOUTIN
BUSBOUTP
BUSBOUTN
Out
Out
Out
Out
Out
Out
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
ACTEL [ Actel Corporation ]
