HD-15531_02 Datasheet, PDF (9/16 Pages) Intersil Corporation – CMOS Manchester Encoder-Decoder

HD-15531
BIPOLAR ONE IN
BIPOLAR ZERO IN
COMMAND SYNC
PARALLEL OUT
SYNC
MSB
VALID
LSB PARITY
P
P
VALID
VALID WORD
FROM PREVIOUS
RECEPTION
FIGURE 5. DECODER TIMING
MIL-STD-1553
The 1553 Standard defines a time division multiplexed data
bus for application within aircraft. The bus is defined to be
bipolar, and encoded in a Manchester II format, so no DC
component appears on the bus. This allows transformer cou-
pling and excellent isolation among systems and their envi-
ronment.
The HD-15531 supports the full bipolar configuration,
assuming a bus driver configuration similar to that in
Figure 1. Bipolar inputs from the bus, like Figure 2, are also
accommodated.
The signaling format in MIL-STD-1553 is specified on the
assumption that the network of 32 or fewer terminals are
controlled by a central control unit by means of Command-
Words, and Data. Terminals respond with Status Words, and
Data. Each word is preceded by a synchronizing pulse, and
followed by parity bit, occupying a total of 20µs. The word
formats are shown in Figure 4. The special abbreviations are
as follows:
P
Parity, which is defined to be odd, taken across all
17 bits.
R/T Receive on logical zero, transmit on ONE.
ME Message Error if logical 1.
TF
Terminal Flag, if set, calls for controller to request
self-test data.
BUS
“1”
+
-
“1”
“1” REF
“0” REF
“0”
-
+
“0”
FIGURE 6. SIMPLIFIED MIL-STD-1553 DRIVER
FIGURE 7. SIMPLIFIED MIL-STD-1553 RECEIVER
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