BU-65170/61580 and BU-61585
MIL-STD-1553A/B NOTICE 2 RT and BC/RT/MT,
ADVANCED COMMUNICATION ENGINE (ACE)
ACE User’s Guide
Also Available
DESCRIPTION
DDC's BU-65170, BU-61580 and
BU-61585 Bus Controller / Remote
Terminal
/
Monitor
Terminal
(BC/RT/MT)
A d v a n c e d
Communication Engine (ACE) termi-
nals comprise a complete integrated
interface between a host processor
and a MIL-STD-1553 A and B or
STANAG 3838 bus.
The ACE series is packaged in a 1.9 -
square-inch, 70-pin, low-profile,
cofired MultiChip Module (MCM)
ceramic package that is well suited for
applications with stringent height
requirements.
The BU-61585 ACE integrates dual
transceiver, protocol, memory man-
agement, processor interface logic,
and a total of 12K words of RAM in a
choice of DIP or flat pack packages.
The BU-61585 requires +5 V power
and either -15 V or -12 V power.
The BU-61585 internal RAM can be
configured as 12K x 16 or 8K x 17.
The 8K x 17 RAM feature provides
capability for memory integrity check-
ing by implementing RAM parity gen-
eration and verification on all access-
es. To minimize board space and
“glue” logic, the ACE provides ultimate
flexibility in interfacing to a host
processor and internal/external RAM.
The advanced functional architecture
of the ACE terminals provides soft-
ware
compatibility
to
DDC's
Advanced Integrated Multiplexer (AIM)
series hybrids, while incorporating a
multiplicity of architectural enhance-
ments. It allows flexible operation
while off-loading the host processor,
ensuring data sample consistency,
and supports bulk data transfers.
The ACE hybrids may be operated at
either 12 or 16 MHz. Wire bond
options allow for programmable RT
address (hardwired is standard) and
external transmitter inhibit inputs.
FEATURES
•
Fully Integrated MIL-STD-1553
Interface Terminal
Interface
•
Flexible Processor/Memory
•
Standard 4K x 16 RAM and
•
Optional RAM Parity
Optional 12K x 16 or 8K x 17 RAM
Available
Generation/Checking
•
Automatic BC Retries
•
Programmable BC Gap Times
•
BC Frame Auto-Repeat
•
Flexible RT Data Buffering
•
Programmable Illegalization
•
Selective Message Monitor
•
Simultaneous RT/Monitor Mode
TX/RX_A
SHARED
RAM
CH. A
TRANSCEIVER
A
DATA
BUFFERS
PROCESSOR
DATA BUS
*
TX/RX_A
DATA BUS
DUAL
ENCODER/DECODER,
MULTIPROTOCOL
AND
MEMORY
MANAGEMENT
D15-D0
TX/RX_B
ADDRESS BUS
ADDRESS
BUFFERS
A15-A0
PROCESSOR
ADDRESS BUS
CH. B
TRANSCEIVER
B
TX/RX_B
PROCESSOR
AND
MEMORY
INTERFACE
LOGIC
TRANSPARENT/BUFFERED, STRBD, SELECT,
RD/WR, MEM/REG, TRIGGER_SEL/MEMENA-IN,
MSB/LSB/DTGRT
IOEN, MEMENA-OUT, READYD
ADDR_LAT/MEMOE, ZERO_WAIT/MEMWR,
8/16-BIT/DTREQ, POLARITY_SEL/DTACK
INT
PROCESSOR
AND
MEMORY
CONTROL
INTERRUPT
REQUEST
RT ADDRESS
RTAD4-RTAD0, RTADP
INCMD
MISCELLANEOUS
CLK_IN, TAG_CLK,
MSTCLR,SSFLAG/EXT_TRG
* SEE ORDERING INFORMATION FOR AVAILABLE MEMORY
FIGURE 1. ACE BLOCK DIAGRAM
©
1992, 1999 Data Device Corporation
TABLE 1. “ACE” SERIES SPECIFICATIONS
PARAMETER
ABSOLUTE MAXIMUM RATING
Supply Voltage
n
Logic +5V
n
Transceiver +5V
n
-15V
n
-12V
Logic
n
Voltage Input Range
RECEIVER
Differential Input Resistance
n
(BU-65170/65180/61585X1,
BU-65170/61580/61585X2)
(Notes 1-7)
n
(BU-65170/65180/61585X3,
BU-65170/61580/61585X6)
(Notes 1-7)
Differential Input Capacitance
n
(BU-65170/65180/61585X1,
BU-65170/61580/61585X2)
(Notes 1-7)
n
(BU-65170/65180/61585X3,
BU-65170/61580/61585X6)
(Notes 1-7)
Threshold Voltage, Transformer
Coupled, Measured on Stub
Common Mode Voltage (Note 7)
TRANSMITTER
Differential Output Voltage
n
Direct Coupled Across 35
Ω,
Measured on Bus
n
Transformer Coupled Across
70
Ω,
Measured on Bus
n
(BU-65170/65180/61585X1,
BU-65170/61580/61585X2,X3,X6)
Output Noise, Differential (Direct
Coupled)
Output Offset Voltage, Transformer
Coupled Across 70 ohms
Rise/Fall Time
LOGIC
V
IH
V
IL
I
IH
(Vcc=5.5V, V
IN
=Vcc)
I
IH
(Vcc=5.5V, V
IN
=2.7V)
n
SSFLAG*/EXT_TRIG
n
All Other Inputs
I
IL
(Vcc=5.5V, V
IN
=0.4V)
n
SSFLAG*/EXT_TRIG
n
All Other Inputs
V
OH
(Vcc=4.5V, 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)
I
OL
n
DB15-DB0, A15-A0, MEMOE*/
ADDR_LAT, MEMWR*/
ZEROWAIT*, DTREQ*/16/8*,
DTACK*/POLARITY_SEL
MIN
TYP
MAX
UNITS
TABLE 1. “ACE” SERIES SPECIFICATIONS (CONTD)
PARAMETER
LOGIC (cont’d)
n
INCMD*, INT* MEMENA_OUT*,
READYD*, IOEN*, TXA, TXA*,
TXB, TXB*, TX_INH_OUT_A*,
TX_INH_OUT_B*,
I
OH
n
DB15-DB0, A15-A0, MEMOE*/
ADDR_LAT, MEMWR*/
ZEROWAIT*, DTREQ*/16/8*,
DTACK*/POLARITY_SEL
n
INCMD*, INT*, MEMENA_OUT*,
READYD*, IOEN*, TXA, TXA*,
TXB, TXB*, TX_INH_OUT_A*,
TX_INH_OUT_B,
C
I
(Input Capacitance)
C
IO
(Bi-directional signal input
capacitance)
POWER SUPPLY REQUIREMENTS
Voltages/Tolerances
n
BU-65170/61580/61585X1
• +5V (Logic)
• +5V (Ch. A, Ch. B)
• -15V (Ch. A, Ch. B)
n
BU-65170/61580/61585X2
• +5V (Logic)
• +5V (Ch. A, Ch. B)
• -12V (Ch. A, Ch. B)
n
BU-65170/61580/61585X3,
BU-65170/61580/61585X6
• +5V (Logic)
• +5V (Ch. A, Ch. B)
Current Drain (Total Hybrid)
n
BU-65170/61580X1
• +5V (Logic, Ch. A, Ch. B)
• -15V (Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X2
• +5V (Logic, Ch. A, Ch. B)
• -12V (Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X3,
BU-65170/61580X6
• +5V (Logic, Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X1
• +5V (Logic, Ch. A, Ch. B)
• -15V (Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
MIN
3.2
TYP
MAX
UNITS
mA
-0.3
-0.3
-18.0
-18.0
-0.3
7.0
7.0
0.3
0.3
Vcc+0.3
V
V
V
V
V
-6.4
mA
11
kΩ
-3.2
mA
2.5
kΩ
50
50
pF
pF
10
pF
5
pF
4.5
5.0
5.5
4.5
5.0
5.5
-15.75 -15.0 -14.25
4.5
4.5
-12.6
5.0
5.0
-12.0
5.5
5.5
-11.4
V
V
V
V
V
V
0.200
0.860
10
Vp-p
Vpeak
6
7
9
Vp-p
4.5
4.75
5.0
5.0
5.5
5.25
mA
mA
20
18
27
27
10
250
-250
100
2.0
-10
-692
-346
-794
-397
2.4
150
Vp-p
Vp-p
mVp-p,
diff
mV
nsec
V
V
µA
µA
µA
µA
µA
V
V
95
30
68
105
180
95
30
80
130
230
190
60
108
160
255
190
60
120
185
305
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
300
0.8
10
-84
-42
-100
-50
0.4
95
245
360
590
105
30
68
105
180
200
350
500
800
240
60
108
160
255
mA
mA
mA
mA
mA
mA
mA
mA
mA
6.4
mA
2
TABLE 1. “ACE” SERIES SPECIFICATIONS (CONTD)
PARAMETER
n
BU-61585X2
TABLE 1. “ACE” SERIES SPECIFICATIONS (CONTD)
PARAMETER
n
BU-61585X1
MIN
TYP
105
30
80
130
230
MAX UNITS
240
60
120
185
305
mA
mA
mA
mA
mA
MIN
TYP
0.335
0.600
0.860
1.385
0.290
0.590
0.890
1.490
MAX UNITS
0.68
1.06
1.45
2.23
0.59
0.92
1.36
2.16
W
W
W
W
W
W
W
W
• +5V (Logic, Ch. A, Ch. B)
• -12V (Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X3,
BU-61585X6
• +5V (Logic, Ch. A, Ch. B)
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
POWER DISSIPATION
Total Hybrid
n
BU-65170/61580X1
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X3,
BU-65170/61580X6
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X1
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X3,
BU-61585X6
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
Hottest Die
n
BU-65170/61580X1
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-65170/61580X3,
BU-65170/61580X6
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
105
255
370
600
250
400
550
850
mA
mA
mA
mA
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X2
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
n
BU-61585X3,
BU-61585X6
• Idle
• 25% Transmitter Duty Cycle
• 50% Transmitter Duty Cycle
• 100% Transmitter Duty Cycle
CLOCK INPUT
Frequency
n
Nominal Value (programmable)
• Default Mode
• Software Programmable Option
n
Long Term Tolerance
• 1553A Mode
• 1553B Mode
n
Short Term Tolerance, 1 second
• 1553A Mode
• 1553B Mode
n
Duty Cycle
• 16 MHz
• 12 MHz
1553 MESSAGE TIMING
Completion of CPU Write (BC Start)-
to-Start of Next Message
BC Intermessage Gap (Note 8)
BC/RT/MT Response Timeout (Note 9)
n
18.5 nominal
n
22.5 nominal
n
50.5 nominal
n
128.0 nominal
RT Response Timeout (Note 11)
Transmitter Watchdog Timeout
THERMAL
Thermal Resistance, Junction-to-Case,
Hottest Die (θJC)
n
BU-65170/61580/61585X1,
BU-65170/61580/61585X2,
n
BU-65170/61580/61585X3,
BU-65170/61580/61585X6
Operating Junction Temperature
Storage Temperature
Lead Temperature (soldering, 10 sec.)
PHYSICAL CHARACTERISTICS
Size
n
BU-65170/61580/61585 S
n
BU-65170/61580/61585 V
0.200
0.630
0.885
1.395
0.25
0.68
1.11
1.97
W
W
W
W
0.850
1.195
1.450
1.975
0.835
1.135
1.435
2.035
1.85
2.25
2.72
3.52
1.67
2.10
2.59
3.46
W
W
W
W
W
W
W
W
16.0
12.0
0.01
0.1
0.001
0.01
33
40
2.5
9.5
17.5 18.5
21.5 22.5
49.5 50.5
127 129.5
4
668
19.5
23.5
51.5
131
7
67
60
MHz
MHz
%
%
%
%
%
%
µs
µs
µs
µs
µs
µs
µs
µs
0.475
0.905
1.160
1.670
0.900
1.245
1.500
2.025
0.885
1.185
1.485
2.085
1.00
1.43
1.86
2.72
2.10
2.50
2.97
3.77
1.92
2.35
2.84
3.71
W
W
W
W
W
W
W
W
W
W
W
W
0.525
0.955
1.210
1.720
1.25
1.68
2.11
2.97
W
W
W
W
6.99
6.8
-55
-65
150
150
+300
°C/W
°C/W
°C
°C
°C
0.335
0.600
0.860
1.385
0.290
0.590
0.890
1.490
0.68
1.06
1.45
2.23
0.59
0.92
1.36
2.16
W
W
W
W
W
W
W
W
1.9 X 1.0 X 0.165
(48.3 x 25.4 x 4.19)
1.9 X 1.0 X 0.150
(48.3 x 25.4 x 3.81)
0.6 (17)
in.
(mm)
in.
(mm)
oz (g)
Weight
n
BU-65170/61580/61585 S/V
0.200
0.630
0.885
1.395
0.25
0.68
1.11
1.97
W
W
W
W
3
Notes for Table 1: 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).
(2) Measurement of impedance is directly between pins TX/RX A(B)
and TX/RX A(B) of the BU-65170/61580XX hybrid.
(3) Assuming the connection of all power and ground inputs to the
hybrid.
(4) The specifications are applicable for both unpowered and powered
conditions.
(5) The specifications assume a 2 volt rms balanced, differential, sinu-
soidal input. The applicable frequency range is 75 kHz to 1 MHz.
(6) Minimum resistance and maximum capacitance parameters are
guaranteed,but not tested, over the operating range.
(7) Assumes a common mode voltage within the frequency range of dc
to 2MHz, applied to pins of the isolation transformer on the stub
side (either direct or transformer coupled), referenced to hybrid
ground. Use a DDC recommended transformer or other transformer
that provides an equivalent minimum CMRR.
(8) Typical value for minimum intermessage gap time. Under software
control, may be lengthened to (65,535µs minus message time), in
increments of 1µs.
(9) Software programmable (4 options). Includes RT-to-RT Timeout
(Mid-Parity of Transmit Command to Mid-Sync of Transmitting RT
Status).
(10) For both +5V logic and transceiver. +5V for channels A and B.
(11) Measured from mid-parity crossing of Command Word to mid-sync
crossing of RT's Status Word.
(12) Specifications for BU-65171, BU-61581, and BU-61586 are identi-
cal to the specifications for the BU-65170, BU-61580, and BU-
61585 respectively.
are programmable by subaddress. These features serve to
ensure data consistency and to off-load the host processor for
bulk data transfer applications.
The ACE series implements three monitor modes: a word moni-
tor, a selective message monitor, and a combined RT/selective
monitor. Other features include options for automatic retries and
programmable intermessage gap for BC mode, an internal Time
Tag Register, an Interrupt Status Register and internal command
illegalization for RT mode.
FUNCTIONAL OVERVIEW
TRANSCEIVERS
The transceivers in the BU-65170/61580X3(X6) are fully mono-
lithic, requiring only a +5 volt power input. Besides eliminating
the need for an additional power supply, the use of a 5 volt (only)
transceiver requires the use of step-up, rather than step-down,
isolation transformers. This provides the advantage of a higher
terminal input impedance than is possible for a 15 volt or 12 volt
transmitter. As a result, there is greater margin for the input
impedance test, mandated for 1553 validation testing. This
allows for longer cable lengths between an LRU's system con-
nector and the isolation transformers of an embedded 1553 ter-
minal.
For the +5 V and -15 V/-12 V front end, the BU-65170/
61580X1(X2) uses low-power bipolar analog monolithic and
thick-film hybrid technology. The transceiver requires +5 V and -
15 V (-12 V) only (requiring no +15 V/+12 V) and includes volt-
age source transmitters. The voltage source transmitters provide
superior line driving capability for long cables and heavy
amounts of bus loading. In addition, the monolithic transceivers
in the BU-65170/61580X1 provide a minimum stub voltage level
of 20 volts peak-to-peak transformer coupled, making them suit-
able for MIL-STD-1760 applications.
The receiver sections of the BU-65170/61580 are fully compliant
with MIL-STD-1553B in terms of front end overvoltage protec-
tion, threshold, common mode rejection, and word error rate. In
addition, the receiver filters have been designed for optimal oper-
ation with the J´ chip's Manchester II decoders.
INTRODUCTION
DDC's ACE series of Integrated BC/RT/MT hybrids provide a
complete, flexible interface between a microprocessor and a
MIL-STD-1553A, B Notice 2, McAir, or STANAG 3838 bus,
implementing Bus Controller, Remote Terminal (RT) and Monitor
Terminal (MT) modes. Packaged in a single 1.9-square-inch,
70-pin DIP or surface mountable flatpack or J-lead package, the
ACE series contains dual low-power transceivers and
encoder/decoders, complete BC/RT/MT multi-protocol logic,
memory management and interrupt logic, 4K x 16 of shared sta-
tic RAM and a direct, buffered interface to a host processor bus.
The BU-65170/61580 contains internal address latches and bidi-
rectional data buffers to provide a direct interface to a host
processor bus. The BU-65170/61580 may be interfaced directly
to both 16-bit and 8-bit microprocessors in a buffered shared
RAM configuration. In addition, the ACE may connect to a 16-bit
processor bus via a Direct Memory Access (DMA) interface. The
BU-65170/61580 includes 4K words of buffered RAM.
Alternatively, the ACE may be interfaced to as much as 64K
words of external RAM in either the shared RAM or DMA config-
urations.
The ACE RT mode is multiprotocol, supporting MIL-STD-1553A,
MIL-STD-1553B Notice 2, STANAG 3838 (including EFAbus),
and the McAir A3818, A5232, and A5690 protocols. Full compli-
ance to the McAir specs, however, requires the use of a sinu-
soidal transceiver (transceiver option 5). Refer to the BU-61590
data sheet for additional information on McAir terminals.
The memory management scheme for RT mode provides an
option for separation of broadcast data, in compliance with
1553B Notice 2. Both double buffer and circular buffer options
J´ DIGITAL MONOLITHIC
The J´ digital monolithic represents the cornerstone element of
the ACE family of terminals. The development of the J´ chip rep-
resents the fifth generation of 1553 protocol and interface design
for DDC. Over the years, DDC's 1553 protocol and interface
design has evolved from: (1) discrete component sets, consisting
of multiple hybrids (with large numbers of chips inside the indi-
vidual hybrids) and programmable logic devices, to (2) multiple
custom ASICs to perform the functions of encoder/decoder and
RT protocol within a single hybrid, to (3) the BUS-61553
Advanced Integrated Mux Hybrid (AIM-HY) series, containing, in
addition to a dual monolithic/thick-film transceiver and discrete
RAM chips, a custom protocol chip and a separate custom mem-
ory management/processor interface chip, to (4) the BUS-61559
Advanced Integrated Mux Hybrids with Enhanced RT Features
(AIM-HY'er — the AIM-HY'er series includes memory manage-
ment and processor interface functions beyond those of the AIM-
HY series) , to (5) the full integration of the J´ chip.
4
The J´ chip consists of a dual encoder/decoder, complete proto-
col for Bus Controller (BC), 1553A/B/McAir Remote Terminal
(RT), and Monitor (MT) modes; memory management and inter-
rupt logic; a flexible, buffered interface to a host processor bus
and optional external RAM; and 4K words of on-chip RAM.
Reference the region within the dotted line of FIGURE 1. Besides
realizing all the protocol, memory management, and interface
functions of the earlier AIM-HY'er series, the J´ chip includes a
large number of enhancements to facilitate hardware and soft-
ware design, and to further off-load the 1553 terminal's host
processor.
put pin (INT) has three software programmable modes of opera-
tion: a pulse, a level output cleared under software control, or a
level output automatically cleared following a read of the
Interrupt Status Register.
Individual interrupts are enabled by the Interrupt Mask Register.
The host processor may easily determine the cause of the inter-
rupt by using the Interrupt Status Register. The Interrupt Status
Register provides the current state of the interrupt conditions.
The Interrupt Status Register may be updated in two ways. In the
standard interrupt handling mode, a particular bit in the Interrupt
Status Register will be updated only if the condition exists and
the corresponding bit in the Interrupt Mask Register is enabled.
In the enhanced interrupt handling mode, a particular bit in the
Interrupt Status Register will be updated if the condition exists
regardless of the contents of the corresponding Interrupt Mask
Register bit. In any case, the respective Interrupt Mask Register
bit enables an interrupt for a particular condition.
DECODERS
The default mode of operation for the BU-65170 RT and BU-
61580 BC/RT/MT requires a 16 MHz clock input. If needed, a
software programmable option allows the device to be operated
from a 12 MHz clock input. Most current 1553 decoders sample
using a 10 MHz or 12 MHz clock. In the 16 MHz mode (default
following a hardware or software reset), the ACE decoders sam-
ple 1553 serial data using the 16 MHz clock. In the 12 MHz
mode, the decoders sample using both clock edges; this pro-
vides a sampling rate of 24 MHz. The faster sampling rate for the
J´ chip’s Manchester II decoders provides superior performance
in terms of bit error rate and zero-crossing distortion tolerance.
For interfacing to fiber optic transceivers for MIL-STD-1773 appli-
cations, a transceiverless version of the J´ chip, the BU-65620,
can be used. These versions provide a pin-programmable option
for a direct interface to the single-ended outputs of a fiber optic
receiver. No external logic is needed.
ADDRESSING, INTERNAL REGISTERS, AND
MEMORY MANAGEMENT
The software interface of the BU-65170/61580 to the host
processor consists of 17 internal operational registers for normal
operation, an additional 8 test registers, plus 64K x 16 of shared
memory address space. The BU-65170/61580's 4K x 16 of inter-
nal RAM resides in this address space. Reference TABLE 2 and
24.
Definition of the address mapping and accessibility for the ACE's
17 non-test registers, and the test registers, is as follows:.
Interrupt Mask Register
is used to enable and disable interrupt
requests for various conditions.
Configuration Registers #1 and #2
are used to select the BU-
61580's mode of operation, and for software control of RT Status
Word bits, Active Memory Area, BC Stop-on-Error, RT Memory
Management mode selection, and control of the Time Tag oper-
ation.
Start/Reset Register
is used for “command” type functions,
such as software reset, BC/MT Start, Interrupt Reset, Time Tag
Reset, and Time Tag Register Test. The Start/Reset Register
includes provisions for stopping the BC in its auto-repeat mode,
either at the end of the current message or at the end of the cur-
rent BC frame.
BC/RT Command Stack Pointer Register
allows the host CPU
to determine the pointer location for the current or most recent
message when the BU-61580 is in BC or RT modes.
BC Control Word/RT Subaddress Control Word Register:
In
BC mode, it allows host access to the current, or most recent BC
Control Word. The BC Control Word contains bits that select the
active bus and message format, enable off-line self-test, mask-
ing of Status Word bits, enable retries and interrupts, and speci-
fy MIL-STD-1553A or -1553B error handling. In RT mode, this
register allows host access to the current or most recent
Subaddress Control Word. The Subaddress Control Word is
used to select the memory management scheme and enable
interrupts for the current message. The read/write accessibility
can be used as an aid for testing the ACE.
TIME TAGGING
The ACE includes an internal read/writable Time Tag Register.
This register is a CPU read/writable 16-bit counter with a pro-
grammable resolution of either 2, 4, 8, 16, 32, or 64
µs
per LSB.
Also, the Time Tag Register may be clocked from an external
oscillator. Another option allows software-controlled increment-
ing of the Time Tag Register. This supports self-testing for the
Time Tag Register. For each message processed, the value of
the Time Tag register is loaded into the second location of the
respective descriptor stack entry (“TIME TAG WORD”) for both
BC and RT modes.
Additional provided options will: clear the Time Tag Register fol-
lowing a Synchronize (without data) mode command or load the
Time Tag Register following a Synchronize (with data) mode
command; enable an interrupt request and a bit setting in the
Interrupt Status Register when the Time Tag Register rolls over
from 0000 to FFFF. Assuming the Time Tag Register is not
loaded or reset, this will occur at approximately 4-second time
intervals, for 64
µs/LSB
resolution, down to 131 ms intervals, for
2
µs/LSB
resolution.
Another programmable option for RT mode is the automatic
clearing of the Service Request Status Word bit following the
ACE's response to a Transmit Vector Word mode command.
INTERRUPTS
The ACE series components provide many programmable
options for interrupt generation and handling. The interrupt out-
5
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