Download Triggering on MIL-STD 1553 Signals

Characterizing the Physical Layer of
MIL-STD 1553 Differential Bus Networks
Presented by:
Johnnie Hancock
Agilent Technologies
Copyright © 2010 Agilent Technologies
Objectives
 Learn how to quickly verify the electrical/physical layer input and
output characteristics of MIL-STD 1553 differential serial buses
using a Digital Storage Oscilloscope (DSO) with MIL-STD 1553
bus decoding and triggering capability.
 Learn how eye-diagram mask testing can provide a composite
measure of the signal integrity of your MIL-STD 1553 differential
bus.
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Copyright © 2010 Agilent Technologies
Agenda




MIL-STD 1553 Protocol & Timing Overview
MIL-STD 1553 Electrical/Physical Layer Requirements
Triggering and Decoding MIL-STD 1553 Serial Buses
Isolating Physical Layer Measurements on Remote Terminal
(RT) and Bus Controller (BC) generated Signals
 MIL-STD 1553 Eye-diagram Mask Testing
 Clock Recovery Technique
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Copyright © 2010 Agilent Technologies
MIL-STD 1553 Protocol & Timing Overview
 Word Length = 20 bits (3-bit Sync field, 16-bit content field, 1-bit parity field)
 Word Types:
 Command (Packets transmitted by BCs)
 Status (Packets transmitted by RTs)
 Data (Packets transmitted by BCs and RTs)
 Baud Rate = 1 Mb/s
 Encoding = Manchester II Bi-phase (except 3-bit Sync field)

Copyright © 2010 Agilent Technologies
4
Manchester II Bi-phase Encoding
NRZ Encoding
 High during middle of bit time = 1
 Low during middle of bit time = 0
Manchester II Bi-phase Encoding
 High to low transition in middle of bit time = 1
 Low to high transition in middle of bit time = 0
5
Copyright © 2010 Agilent Technologies
Message Formats (Master/Slave Relationship)
Example #1: BC to RT Transfers (BC sends data to RT)
A
B
B
B
C
A Packet - Command Word from BC to RTA = 0F w/ receive bit set: “Get ready accept data.”
B Packets - 5 Data Words transmitted from BC to RT
C Packet - Status Word from RTA = 0F: “Got it!”
A
B
B
B
B
B
C
Note: Signals probed at BC input/output test plane
6
Copyright © 2010 Agilent Technologies
Message Formats (Master/Slave Relationship)
Example #2: RT to BC Transfers (BC requests data from RT)
A
B
C
C
C
A Packet - Command Word from BC to RTA = 02 w/ transmit bit set: “Send me data.”
B Packet - Status Word from RTA = 02: “Here it comes!”
C Packets - 4 Data Words transmitted from RT to BC
B
C
C
C
C
A
Note: Signals probed at RT input/output test plane
7
Copyright © 2010 Agilent Technologies
Message Formats (Master/Slave Relationship)
Example #3: RT to RT Transfers (BC requests RT “2” to send data to RT “1”)
A
B
C
D
D
E
D
A Packet - Command Word from BC to RTA “1” w/ receive bit set: “Get ready accept data.”
B Packet – Command Word from BC to RTA “2” w/ transmit bit set: “Send data to RT “2”.”
C Packet – Status Word from RTA “2”: “Here it comes!”
D Packets - N Data Words transmitted from RT “2” to RT “1”
E Packet – Status Word from RTA “1”: “Got it!”
C
A
D
D
D
B
D
E
Scope waveforms not available
Note: Signals probed at RT2 input/output test plane
8
Copyright © 2010 Agilent Technologies
Primary Electrical/Physical Layer Specifications
Transformer Coupled
Direct Coupled
18 to 27 V p-p
6 to 9 V p-p
≤ 900 mV
≤ 300 mV
≤ 14 mV RMS
≤ 5 mV RMS
100 to 300 ns (10/90)
100 to 300 ns (10/90)
≤ 25 ns
≤ 25 ns
< 250 mV
< 90 mV
0.86 to 14 V p-p
1.2 to 20 V p-p
≤ 0.2 V
≤ 0.28 V
≤ 150 ns
≤ 150 ns
Terminal Output Specs
Voltage Swing
Overshoot
Noise
Transition Time
Zero Crossing Distortion
Output Symmetry
Terminal Input Specs
Voltage Swing
Input Rejection V
Zero Crossing Distortion
Other Important Timing Parameters
Intermessage Gap: ≥ 4 µs (parity bit crossing to next sync edge)
Response Time: 4 to 12 µs (parity bit crossing to next sync edge)
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Copyright © 2010 Agilent Technologies
Measurement Test Planes
 All terminals are transceivers.
 Both output/transmitted and input/received signals are present at all
differential terminal I/O pins.
 Making oscilloscope parametric and timing measurements on specific
transmitted or received words can be enhanced with “intelligent” oscilloscope
triggering.
Data Device Corporation Graphic
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Copyright © 2010 Agilent Technologies
The Problem: Most of today’s scopes trigger on simple
edge crossing conditions
 Simple “edge” triggering can’t differentiate between transmitted and received words.
 External/synchronization signals are rarely available.
 Resultant measurements and display are composites of ALL words.
11
Copyright © 2010 Agilent Technologies
Required MIL-STD 1553 Triggering
1
1
2
3
Input Measurements
 Received signals at BC transmitted from RT1
 Probe at BC
 Trigger on Status Words from RTA = 1
Output Measurements
 Transmitted signals at BC
 Probe at BC
 Trigger on Command Words
 Received signals at RT1 transmitted from BC
 Probe at RT1
 Trigger on Command Words
 Transmitted signals at RT1
 Probe at RT1
 Trigger on Status Words from RTA = 1
 Received signals at RT2 transmitted from RT3
 Probe at RT2
 Trigger on Status Words with RTA = 3
 Transmitted signals at RT2
 Probe at RT2
 Trigger on Status Words with RTA = 2
 Transmitted signals at RT3
 Probe at RT3
 Trigger on Status Words with RTA = 3
Note 1: Bus Monitor (protocol analyzer)
12
Copyright © 2010 Agilent Technologies
Triggering on MIL-STD 1553 Signals
Triggering options:
 Data Word Start
 Data Word Stop
 Command/Status Word Start
 Command/Status Word Stop
 Remote Terminal Address
 RTA + 11 Bits
 Parity Error
 Sync Error
 Manchester Error
Note: The “RTA + 11 bits” trigger mode can be used to trigger on
and differentiate between specific Command and Status Words.
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Command versus Status Word Triggering
Using the “RTA + 11 bits” Trigger Mode
Command Word Trigger
Status Word Trigger
Trigger
Trigger
Status Word
Command Word
Status Word
Command Word
Trigger: RTA + 11 bits = 02HEX + 1 11110 XXXXX
Sub-address = 30 (decimal)
Trigger: RTA + 11 bits = 02HEX + X 0X000 XXXXX
Status bits
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Measuring received signals at RT2 transmitted by the BC
Rise Time & V p-p @ RT input
2
1
Command Word received from BC
3
T/R
Sub-Address
MIL-STD 1553 Trigger Setup
(Command Word Trigger: RTA = 2, Transmit, Sub = 1110)
15
Copyright © 2010 Agilent Technologies
Measuring received signals at RT2 transmitted by the BC
Response Time
2
1
Response Time
3
T/R
Sub-Address
MIL-STD 1553 Trigger Setup
(Command Word Trigger: RTA = 2, Transmit, Sub = 1110)
16
Copyright © 2010 Agilent Technologies
Measuring received signals at RT2 transmitted by the BC
Intermessage Gap Time
2
1
3
Intermessage
Gap
T/R
Sub-Address
MIL-STD 1553 Trigger Setup
(Command Word Trigger: RTA = 2, Transmit, Sub = 1110)
17
Copyright © 2010 Agilent Technologies
MIL-STD 1553 Eye-diagram Mask Testing
Eye-diagram measurements provide a composite measure of overall
system signal integrity by overlaying all bits of each word.
 Eye-diagrams display worst-case jitter, vertical
noise, & signal anomalies.
 Conventional eye-diagrams measurements
require a reference clock signal for triggering.
Vertically closing eye due to noise
and/or insufficient signal level
 MIL-STD 1553 signals don’t supply an explicit
reference clock signal.
 Generating MIL-STD eye-diagram measurements
requires either a software- or hardware-recovered
clock.
Horizontally closing eye due to jitter
and/or signal timing errors
Page 18
Copyright © 2010 Agilent Technologies
November 2007
MIL-STD 1553 Hardware Clock Recovery Algorithm
1. Scope triggers on specific word in order to
capture and display input or output signals at a
particular test plane.
2. Scope’s timebase is scaled to repetitively capture
just the 1st Manchester-encoded bit (bit #4) for 50
milliseconds with infinite-persistence turned on.
3. Scope’s timebase is scaled to repetitively capture
just the 2nd Manchester-encoded bit (bit #5) for 50
milliseconds with infinite-persistence turned on.
4. Scope steps through and repetitively captures all
17 Manchester-encoded bits (bits 4 through 20)
for 50 milliseconds each with infinite persistence
turned on, and then repeats.
Note: This is an automated test sequence that runs within the scope when a MIL-STD 1553 mask test file is recalled.
Page 19
Copyright © 2010 Agilent Technologies
November 2007
“Building” the MIL-STD 1553 Eye
Sync Field = Bits 1 - 3
Bit #4
Bit #5
Bit #6
Bit #7
Bit #8
Bit #9
…
Bit #4
Bit #5
Bit #7
Bit #6
Bit #8
Bit #9
Bits 4 - 20
Page 20
Copyright © 2010 Agilent Technologies
November 2007
…
The MIL-STD 1553 “Double Eye”
 With Manchester encoding, the MIL-Std 1553 eye-diagram measurement consists
of 2 eyes/bit.
 Signal transitions should always occur near mid-point of each bit time.
 Signal transitions may or may not occur near bit time boundaries.
 The diamond-shaped pass/fail mask is based on the “voltage swing”
(0.86 V p-p for xformer coupled @ input test plane) and “zero-crossing-distortion”
(+/- 150 ns @ input test plane) specifications.
Page 21
Copyright © 2010 Agilent Technologies
November 2007
Summary
 The electrical/physical layer of MIL-STD 1553 networks should be
characterized to insure good signal integrity for reliable communication.
 Using an oscilloscope with built-in MIL-STD 1553 triggering and decoding
will enhance your ability to quickly window-in on specific transmitted and
received words for physical layer characterization.
 MIL-STD 1553 eye-diagram mask testing provides a composite measure of
your systems physical layer characteristics.
Page 22
Copyright © 2010 Agilent Technologies
November 2007
Agilent’s InfiniiVision Series Oscilloscopes
Engineered for Best Signal Visibility
MSO/DSO7000B
DSO5000A
MSO/DSO6000A
MSO/DSO6000L
Series
Bandwidth
Sample
Rate
(Max)
Memory
Depth
MSO
Display
7000B
100 MHz to 1 GHz
4 GSa/s
8M
Yes
6000A
100 MHz to 1 GHz
4 GSa/s
8M
6000L
100 MHz to 1 GHz
4 GSa/s
100 MHz to 500
2 GSa/s
Option 553: MIL-STD MHz
1553 Trigger & Decode
5000A
Seg
Mem
Battery
Option
12.1”
XGA
Yes
No
Yes
6.3” XGA
Yes
Yes
8M
Yes
None
Yes
No
8M
No
6.3” XGA
Yes
No
Option LMT: Mask Testing
N2791A: 25-MHz Differential Active Probe
Page 23
Copyright © 2010 Agilent Technologies
Application-specific Measurement Options for
InfiniiVision Series Oscilloscopes
Measurement
Factory-installed Option
After-purchase Upgrade
MIL-STD 1553
Option 553
N5469A
I2C/SPI
Option LSS
N5423A
RS-232/UART
Option 232
N5457A
CAN/LIN
Option AMS
N5424A
FlexRay
Option FLX
N5432C
I2S
Option SND
N5468A
Mask Test
Option LMT
N5455A
Segmented Memory
Option SGM
N5454A
Page 24
Copyright © 2010 Agilent Technologies
Characterizing the Physical Layer of
MIL-STD 1553 Differential Bus Networks
Page 25
Copyright © 2010 Agilent Technologies
November 2007
Page 26
Copyright © 2010 Agilent Technologies
November 2007
Agilent’s InfiniiVision Series Oscilloscopes
for MIL-STD 1553 Testing (Option 5531)
 Compatible models: All 5000, 6000, and 7000 series
4-channel DSOs and 4+16 channel MSOs
 Industry’s only hardware-based decode enhances
probability of capturing MIL-STD 1553 communication
errors
 Flexible MIL-STD 1553 triggering modes
 Automatic Search & Navigation (7000B only)
 Optional battery operation (6000A series only)
 MIL-STD 1553 eye-diagram mask testing (requires
Option LMT2)
 Entry-level Price:
 DSO5014A  Option 5531  Option LMT2  N2791A Diff Probe Total System Price -
$5300
$1300
$ 700
$ 600
$7900
Notes:
1. For after-purchase upgrade on an existing oscilloscope order N5469A.
2. For after-purchase upgrade on an existing oscilloscope order N5455A.
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Decoding the MIL-STD 1553 Bus
Decode Display:
 “Lister” table
 Time-aligned trace
Numeric/Symbol Format:
 HEX
 Binary
 Basic Word-type Symbol
Word Type:
 Cmd/Status (green)
 Data (white)
Bits:
 Remote Terminal Address (green)
 Command/Status Bits 9-19 (green)
 16 Bits of Data Word (white)
Errors
 Parity (red)
Time-aligned
Decode Trace
 Sync (red)
 Manchester (red)
Decode “Lister”
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Time-Aligned Decode Trace
Binary Decode
Data Word
Sync
Command/Status Word
Sync
HEX Decode
RTA
11 Bits
Word Type
16 Bits
Word Type
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Triggering on MIL-STD 1553 Signals
Triggering options:
 Data Word Start
 Data Word Stop
 Command/Status Word Start
 Command/Status Word Stop
 Remote Terminal Address
 RTA + 11 Bits
 Parity Error
 Sync Error
 Manchester Error
Note: The “RTA + 11 bits” trigger mode can be used to trigger on
and differentiate between specific Command and Status Words.
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Command versus Status Word Triggering
Using the “RTA + 11 bits” Trigger Mode
Command Word Trigger
Status Word Trigger
Trigger
Trigger
Status Word
Command Word
Status Word
Command Word
Trigger: RTA + 11 bits = 02HEX + 1 11110 XXXXX
Sub-address = 30 (decimal)
Trigger: RTA + 11 bits = 02HEX + 0 00000 00000
Status bits
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Error Analysis and Triggering
Sync Error
Parity Error
Manchester Encoding Error
Manchester Encoding Error = Missing transition within bit time
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Automatic Search & Navigation
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
MIL-STD 1553 Mask Test Files
Free downloadable mask files:
 System xfmr-coupled Input.msk
 System direct-coupled Input.msk
 BC to RT xfmr-coupled Input.msk
 BC to RT direct-coupled Input.msk
 RT to BC xfmr-coupled Input.msk
 RT to BC direct-coupled Input.msk
 RT to RT xfmr-coupled Input.msk
 RT to RT direct-couple Input.msk
MIL-STD 1553 eye-diagram mask test files can downloaded at:
www.agilent.com/find/1553
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009
Probing a MIL-STD 1553 Differential Bus
 The MIL-STD 1553 differential bus must be
probed with a differential active probe.
 Output of differential probe must be fed into two
channels of the scope in order to establish dual
threshold triggering (upper and lower thresholds).
Probe Output
Agilent’s N2791A 25-MHz differential
active probe is recommended (US$600).
MIL-STD
1553
Option
Copyright © 2010 Agilent Technologies
August 2009