BU-61703/61705
SIMPLE SYSTEM RT (SSRT)
DESCRIPTION
The BU-61703/5 Simple System RT
(SSRT) MIL-STD-1553 terminals pro-
vide a complete interface between a
simple system and a MIL-STD-1553
bus. These terminals integrate dual
transceiver, protocol logic, and a FIFO
memory for received messages in a
1.0 inch square ceramic package. The
SSRT provides multi-protocol support
of MIL-STD-1553A/B, MIL-STD-1760,
McAir, and STANAG-3838.
The SSRT's transceivers are complete-
ly monolithic, require only a +5V sup-
ply, and consume low power. There are
versions of the simple system RT avail-
able with transceivers trimmed for MIL-
STD-1760 compliance, or compatible
to McAir standards. As a means of fur-
ther reducing power consumption, the
SSRT is available in versions with its
logic powered by +3.3V, or +5V. The
SSRT can operate with a choice of
clock frequencies of 10, 12, 16, or 20
MHz.
The SSRT is ideal for stores and other
simple systems that do not require a
microprocessor. To streamline the inter-
face to simple systems, the SSRT
Note: Transformers are external.
55Ω
BUS A
55Ω
TRANSMITTER
INHIBIT
TX_INH
55Ω
BUS B
55Ω
B-3226
B-3227
MSTCLR
TX/RX B
TX/RX B
TRANSCEIVER
B
TX/RX A
FEATURES
•
Complete Integrated Remote
includes an internal 32-word FIFO for
received data words. This serves to
ensure that only complete, consistent
blocks of validated data words are
transferred to a system.
The SSRT incorporates a built-in self-
test (BIT). This BIT, which is processed
following power turn-on or after receipt
of an Initiate self-test mode command,
provides a comprehensive test of the
SSRT's encoders, decoders, protocol,
transmitter watchdog timer, and proto-
col. The result of the built-in test may be
conveyed to the bus controller by
means of the SSRT's Terminal Flag bit
and/or its RT BIT word.
The SSRT includes an auto-configura-
tion feature. This may be used to
enable the SSRT to run (or not run) its
BIT at power turn-on, to select between
MIL-STD-1553A or -1553B protocol, to
transfer received data words to a sys-
tem either individually or by means of a
burst transfer, to implement wrap-
around for subaddress 30 (per MIL-
STD-1553B Notice 2), along with
options involving the reporting of self-
test failures and loopback errors.
B-3226
B-3227
Terminal Including:
Dual Low-Power 5V Only Transceiver
Complete RT Protocol Logic
STANAG-3838 RT, and
MIL-STD-1760 Stores Management
•
Supports MIL-STD-1553A/B Notice 2,
•
1.0 X 1.0 Inch, 72-pin Package
•
Choice of 5V or 3.3V Logic Power
•
Meets 1553A/McAir Response Time
Requirements
•
Internal FIFO for Burst Mode
Capability on Receive Data
•
16-bit DMA Interface
•
Auto Configuration Capability
•
Comprehensive Built-in Self-test
•
Direct Interface to Simple
(Processorless) Systems
10, 12, 16, or 20 MHz
•
Selectable Input Clock:
TX/RX A
TRANSCEIVER
A
DATA
BUFFERS
DMA
HANDSAKE
AND
TRANDFER
CONTROL
LOGIC
D15-D0
DTREQ
DTGRT
DTACK
HS FAIL
MEMOE
MEMWR
SYSTEM
DATA
DMA
HANDSAKE
CONTROL
DATA
TRANSFER
CONTROL
CONTROL
INPUTS
AUTO_CFG
BRO_ENA
DUAL
ENCODER
DECODER
AND
RT STATE
LOGIC
L_BRO, T/R, SA4-SA0
WC/MC/CWC4-0
COMMAND
ADDRESS
BUS
ILLEGAL
RTAD4-RTAD0
SRV_RQST
SSFLAG
BUSY
RTACTIVE
INCMD
RT
ADDRESS
RTADP
RT_AD_LAT
RT_AD_ERR
RT
WORD
INPUTS
CLK_IN
GBR
MSG_ERR
RTFAIL
CLOCK
FEQUENCEY
SELECTION
CLK_SEL1
CLK_SEL0
RT
MESSAGE
STATUS
FIGURE 1. BU-61703/5 BLOCK DIAGRAM
©
2000 Data Device Corporation
TABLE 1. SIMPLE SYSTEM RT SPECIFICATIONS
PARAMETER
ABSOLUTE MAXIMUM RATING
Supply Voltage
!
Logic +5V or +3.3V
!
RAM +5V
!
Transceiver +5V
!
Voltage Input Range for +5V
Powered Logic (BU-61705)
!
Voltage Input Range for +3.3V
Powered Logic (BU-61703)
RECEIVER
Differential Input Resistance
(Notes 1-6)
Differential Input Capacitance
(Notes 1-6)
Threshold Voltage, Transformer
Coupled,
Common Mode Voltage (Note 7)
TRANSMITTER
Differential Output Voltage
!
Direct Coupled Across 35
Ω,
Measured on Bus
!
Transformer Coupled Across
70
Ω,
Measured on Bus
BU-61573(5)XX-XX0 (Note 8)
BU-61573(5)XX-XX2
(Note 8, 9,13)
Output Noise, Differential (Direct
Coupled)
Output Offset Voltage, Transformer
Coupled Across 70 ohms
Rise/Fall Time
BU-61703(5)X3
BU-61703(5)X4
LOGIC
V
IH
All signals except CLK_IN
CLK_IN
V
IL
All signals except CLK_IN
CLK_IN
Schmidt Hysteresis
All signals except CLK_IN
CLK_IN
I
IH
(Vcc=5.5V, V
IN
=Vcc)
I
IH
(Vcc=5.5V, V
IN
=2.7V)
I
IH
(Vcc=3.6V, V
IN
=Vcc)
I
IH
(Vcc=3.6V, V
IH
=2.7V)
I
IL
(Vcc=5.5V, V
IH
=0.4V)
I
IL
(Vcc=3.6V, V
IH
=0.4V)
V
OH
(Vcc=4.5V, V
IH
=2.7V,
V
IL
=0.2V, I
OH
=max)
V
OH
(Vcc=3.0V, V
IH
=2.7V,
V
IL
=0.2V, I
OH
=max)
V
OL
(Vcc=4.5V, V
IH
=2.7V,
V
IL
=0.2V, I
OL
=max)
V
OL
(Vcc=3.0V, V
IH
=2.7V,
V
IL
=0.2V, I
OL
=max)
I
OL
I
OH
C
I
(Input Capacitance)
C
IO
(Bi-directional signal input
capacitance)
MIN
TYP
MAX
UNITS
TABLE 1. SIMPLE SYSTEM RT SPECIFICATIONS (Cont’d)
PARAMETER
POWER SUPPLY REQUIREMENTS
Voltages/Tolerances
!
+5V Logic (BU-61705) (Note 10)
!
+3.3V Logic (BU-61703) (Note 10)
!
+5V Ch. A, +5, Ch. B (Note 10)
Current Drain
!
BU-61705XX-XX0
!
+5V (Logic, CH A, CH B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-61705XX-XX2
!
+5V (Logic, CH A, CH B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-61703XX-XX0
!
+5V (CH A, CH B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
3.3V (Logic)
!
BU-61703XX-XX2
!
+5V (CH A, CH B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
3.3V (Logic)
POWER DISSIPATION
Total Hybrid (Note 11)
!
BU-61705XX-XX0
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-61705XX-XX2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-61703XX-XX0
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-61703XX-XX2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
Hottest Die (Note 11)
!
BU-6170XXX-XX0
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
!
BU-6170XXX-XX2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
MIN
TYP
MAX UNITS
-0.3
-0.3
-0.3
-0.3
-0.3
2.5
6.0
6.0
7.0
6.0
6.0
V
V
V
V
V
KΩ
4.5
3.0
4.75
5.0
3.3
5.0
5.5
3.6
5.5
V
V
V
160
265
370
580
mA
mA
mA
mA
5
0.200
0.860
10
pF
Vp-p
Vpeak
160
276
392
625
mA
mA
mA
mA
6
7
9
Vp-p
18
20
20
22
27
27
10
Vp-p
Vp-p
M
V
P
-
P
100
205
310
520
40
mA
mA
mA
mA
mA
-250
150
250
mV
peak
100
216
332
565
40
mA
mA
mA
mA
mA
100
200
150
250
300
300
nsec
nsec
2.1
0.8•Vcc
0.7
0.2•Vcc
0.4
1.0
-10
-350
-10
-350
-350
-350
2.4
2.4
0.4
0.4
3.4
-3.4
50
50
V
V
V
V
V
V
µA
µA
µA
µA
µA
µA
V
V
V
V
mA
mA
pF
pF
0.88
1.11
1.33
1.79
0.88
1.17
1.46
2.05
0.69
0.92
1.15
1.60
0.69
0.98
1.28
1.86
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
10
-50
10
-33
-50
-33
0.28
0.51
0.75
1.22
0.28
0.58
0.88
1.48
W
W
W
W
W
W
W
W
2
TABLE 1. SIMPLE SYSTEM RT SPECIFICATIONS (Cont’d)
PARAMETER
CLOCK INPUT
Frequency
!
Nominal Value
• Default
• Option
• Option
• Option
!
Long Term Tolerance
• 1553A Compliance
• 1553B Compliance
!
Short Term Tolerance, 1 second
• 1553A Compliance
• 1553B Compliance
!
Duty Cycle
1553 MESSAGE TIMING
RT-to-RT Response Timeout
(Note 12)
RT Response Time
(mid-parity to mid-sync) (Note 12)
Transmitter Watchdog Timeout
THERMAL
Thermal Resistance, Junction-to-Case,
Hottest Die (θ
JC
)
Operating Junction Temperature
Storage Temperature
Lead Temperature (soldering, 10 sec.)
PHYSICAL CHARACTERISTICS
Size
1.0 X 1.0 X 0.155
(25.4 x 25.4 x 3.94)
Weight
0.6
(17)
NOTES:
Notes 1 through 6 are applicable to the Receiver Differential Resistance
and Differential Capacitance specifications:
(1)
Specifications include both transmitter and receiver (tied together
internally).
Impedance parameters are specified directly between pins
TX/RX A(B) and
TX / RX A(B)
of the SSRT hybrid.
It is assumed that all power and ground inputs to the hybrid are con-
nected.
The specifications are applicable for both unpowered and powered
conditions.
The specifications assume a 2 volt rms balanced, differential, sinu-
soidal input. The applicable frequency range is 75 kHz to 1 MHz.
Minimum resistance and maximum capacitance parameters are
guaranteed over the operating range, but are not tested.
Assumes a common mode voltage within the frequency range of dc
to 2 MHz, applied to the pins of the isolation transformer on the stub
side (either direct or transformer coupled), and referenced to hybrid
oz
(g)
in.
(mm)
MIN
TYP
MAX
UNITS
NOTES: (Cont’d)
ground. Transformer must be a DDC recommended transformer or
other transformer that provides an equivalent minimum CMRR.
16.0
12.0
10.0
20.0
-0.01
-0.10
0.001
-0.01
40
0.01
0.1
0.001
0.01
60
MHz
MHz
MHz
MHz
%
%
%
%
%
(8)
An "X" in one or more of the product type fields indicates that the ref-
erence is applicable to all available product options.
MIL-STD-1760 requires an output of 20 Vp-p minimum on the stub
connection.
(9)
(10) External 10 µF tantalum and 0.1 µF capacitors to ground should be
located as close as possible to Pins 20 and 72, and a 0.1 µF capac-
itor at pin 37.
(11) Power dissipation specifications assume a transformer coupled con-
figuration, with external dissipation (while transmitting) of 0.14 watts
for the active isolation transformer, 0.08 watts for the active bus cou-
pling transformer, 0.45 watts for each of the two bus isolation resis-
tors, and 0.15 watts for each of the two bus termination resistors.
(12) Measured from mid-parity crossing of command word to mid-sync
crossing of RT's status word.
(13) MIL-STD-1760 compliant output voltage not available for
BU-61703/5X4 versions.
17.5
4
18.5
19.5
7
µs
µs
µs
660.5
-55
-65
20
150
150
+300
°C/W
°C
°C
°C
(2)
(3)
(4)
(5)
(6)
(7)
3
INTRODUCTION
GENERAL
The BU-61703/5 Simple System RT (SSRT) is a complete MIL-
STD-1553 Remote Terminal (RT) bus interface unit. Contained in
this hybrid are a dual transceiver and Manchester II
encoder/decoder, and MIL-STD-1553 Remote Terminal (RT) pro-
tocol logic. Also included are built-in self-test capability and a par-
allel subsystem interface. The subsystem interface includes a 12-
bit address bus and a 16-bit data bus that operates in a 16-bit
DMA handshake transfer configuration. The local bus and associ-
ated control signals may be operated from either +5 volt or +3.3
volt power.
The transceiver front end of the BU-61703/5 is implemented by
means of low-power monolithic technology. The transceiver
requires only a single +5 V voltage source. The voltage source
transmitters provide superior line driving capability for long cables
and heavy amounts of bus loading. In addition, the monolithic
transceivers provide a minimum stub voltage level of 20 volts
peak-to-peak transformer coupled, making the BU-61703/5 suit-
able for MIL-STD-1760 applications.
The receiver sections of the BU-61703/5 are fully compliant with
MIL-STD-1553B in terms of front-end overvoltage protection,
threshold, and bit-error rate.
The BU-61703/5 implements all MIL-STD-1553 message formats,
including all 13 MIL-STD 1553 dual redundant mode codes. Any
subset of the possible 1553 commands (broadcast, T/R bit, sub-
address, word count/mode code) may be optionally illegalized by
means of an external PROM, PLD, or RAM. An extensive amount
of message validation is performed for each message received.
Each word received is validated for correct sync type and sync
encoding, Manchester II encoding, parity, and bit count. All mes-
sages are verified to contain a legal, defined command word and
correct word count. If the BU-61703/5 is the receiving RT in an RT-
to-RT transfer, it verifies that the T/R bit of the transmit command
word is logic "1" and that the transmitting RT responds in time and
contains the correct RT address in its Status Word.
The BU-61703/5 may be operated from a 10, 12, 16, or 20 MHz
clock input. For any clock frequency, the decoder samples incom-
ing data on
both
edges of the clock input. This oversampling, in
effect, provides for a sampling rate of twice the input clocks' fre-
quency. Benefits of the higher sampling rate include a wider toler-
ance for zero-crossing distortion and improved bit error rate per-
formance.
The BU-61703/5 includes a hardwired R.T. address input. This
includes 5 address lines, an address parity input, and an address
parity error output. The RT address can also be latched by means
of a latching input signal.
The BU-61703/5 supports command illegalization. Commands
may be illegalized by asserting the input signal
ILLEGAL
active
low within approximately 2 µs after the mid-parity bit zero-crossing
of the received command word. Command words may be illegal-
ized as a function of broadcast,
T / R
bit, subaddress, word count,
and/or mode code.
An internal Built-in-Test (BIT) Word register is updated at the end
of each message. The contents of the BIT Word Register are
transmitted in response to a Transmit BIT Word Mode Command.
The BU-61703/5 provides a number of real-time output signals.
These various signals provide indications of message in progress,
valid received message, message error, handshake fail, loop-test
fail or transmitter timeout.
The BU-61703/5 includes standard DMA handshake signals
(Request, Grant, and Acknowledge) as well as transfer control out-
puts (
MEMOE
and
MEMWR
). The DMA interface operates in a
16-bit mode, supporting word-wide transfers.
The SSRT's system interface allows the BU-61703/5 to be inter-
faced directly to a simple system that doesn't include a micro-
processor. This provides a low-cost 1553 interface for A/D and D/A
converters, switch closures, actuators, and other discrete I/O sig-
nals.
The BU-61703/5 has an internal FIFO for received data words.
This 32-word deep FIFO may be used to allow the BU-61703/5 to
transfer its data words to the local system in burst mode. Burst
mode utilizes the FIFO by transferring data to the local bus at a
rate of one data word every three clock cycles. Burst mode nego-
tiates only once for use of the subsystem bus. Negotiation is per-
formed only after all 1553 data words have been received and val-
idated. In non-burst mode, the BU-61703/5 will negotiate for the
local bus after every received data word. The data word transfer
period is three clock cycles for each received 1553 data word.
The BU-61703/5 may also be used in a shared RAM interface con-
figuration. By means of tri-state buffers and a small amount of
"glue" logic, the BU-61703/5 will store Command Words and
access Data Words to/from dedicated "mailbox" areas in a shared
RAM for each broadcast / T/R bit / subaddress / mode code.
4
ADDRESS MAPPING:
A typical addressing scheme for the BU-61703/5 12-bit address
bus could be as follows:
A11:
A10:
A9-A5:
A4-A0:
BROADCAST / OWNADDRESS
TRANSMIT/ RECEIVE
DMA READ OPERATION
In response to a transmit command, the BU-61703/5 needs to
read data words from the external subsystem. To initiate a data
word read transfer, the SSRT asserts the signal
DTREQ
low.
Assuming that the subsystem asserts
DTGRT
in time, the SSRT
will then assert the appropriate values of L_BRO (logic "0"),
T / R
(high), SA4-0, and MC/CWC4-0;
MEMWR
high, along with
DTACK
low and
MEMOE
low to enable data to be read from the
subsystem.
After the transfer of each Data Word has been completed, the
value of the address bus outputs CWC4 through CWC0 is incre-
mented.
SUBADDRESS 4-0
WORD COUNT/MODE CODE 4-0
This method of address mapping provides for a "mailbox" alloca-
tion scheme for the storage of data words. The 12 address outputs
may be used to map into 4K words of processor address space.
The BU-61703/5's addressing scheme maps messages in terms
of broadcast/own address, transmit/receive, subaddress, and
word/count mode code. A 32-word message block is allocated for
each T/R-subaddress.
For non-mode code messages, the Data Words to be transmitted
or received are accessed from (to) relative locations
0 through 31 within the respective message block. For the
MIL-STD-1553B Synchronize with data, Selected transmitter shut-
down, Override selected transmitter shutdown, and Transmit vec-
tor word mode commands which involve a single data word trans-
fer, the address for the data word is offset from location 0
of the message block for subaddresses 0 and 31 by the value of
the mode code field of the received command word.
The data words transmitted in response to the Transmit last com-
mand or Transmit BIT word mode commands are accessed from
a pair of internal registers.
DMA WRITE OPERATION
In response to a receive command, the BU-61703/5 will need to
transfer data to the subsystem. There are two options for doing
this, the burst mode and the non-burst mode. In burst mode,
all
received data words are transferred from the SSRT to the subsys-
tem in a contiguous burst, only following the reception of the cor-
rect number of valid data words. In the non-burst mode,
single
data words are written to the external subsystem immedi-
ately following the reception of each individual data word.
To initiate a DMA write cycle, the SSRT asserts
DTREQ
low. The
subsystem must then respond with
DTGRT
low. Assuming that
DTGRT
was asserted in time, the BU-61703/5 will then assert
DTACK
low. The BU-61703/5 will then assert the appropriate
value of L_BRO,
T / R
, SA4-0, and MC/CWC4-0,
MEMOE
high,
and
MEMWR
low.
MEMWR
will be asserted low for one clock
cycle. The subsystem may then use either the falling or rising edge
of
MEMWR
to latch the data. Similar to the DMA read operation,
the address outputs CWC4 through CWC0 are incremented after
the completion of a DMA write operation.
DMA INTERFACE
A 16-bit data bus, a 12-bit address bus, and six control signals are
provided to facilitate communication with the parallel subsystem.
The data bus D15-D0 consists of bi-directional tri-state signals.
The address bus L_BRO,
T / R
, SA4-SA0, and WC/MC/CWC4-0;
along with the data transfer control signals
MEMOE
and
MEMWR
are two-state output signals.
The control signals include the standard DMA handshake signals
DTREQ
,
DTGRT
,
DTACK
, as well as the transfer control outputs
MEMOE
and
MEMWR
.
HS _ FAIL
provides an indication to the
subsystem of a handshake failure condition.
Data transfers between the subsystem and the BU-61703/5 are
performed by means of a DMA handshake, initiated by
the BU-61703/5. A data read operation is defined to be the trans-
fer of data from the subsystem to the BU-61703/5. Conversely, a
data write operation transfers data from the BU-61703/5 to the
subsystem. Data is transferred as a single 16-bit word
HANDSHAKE FAIL
Following the assertion of
DTREQ
low by the SSRT, the external
subsystem has 10 µs to respond by asserting
DTACK
to
logic "0".
If the BU-61703/5 (SSRT) asserts
DTREQ
and the subsystem
does not respond with
DTGRT
in time for the BU-61703/5 to com-
plete a data word transfer, the
HSFAIL
output will be asserted low
to inform the subsystem of the handshake failure, and bit 12 in the
internal Built-In-Test (BIT) word will be set to logic "1." If the hand-
shake failure occurs on a data word read transfer (for a transmit
command), the SSRT will abort the current message transmis-
sion. In the case of a handshake failure on a write transfer
(received command) the SSRT will set the handshake failure out-
put and BIT word bit, and abort processing the current message.
5
Embedded System
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