Copyright © 2010 Agilent Technologies Characterizing the Physical Layer of MIL-STD 1553 Differential Bus Networks Presented by: Johnnie Hancock Agilent Technologies

Copyright © 2010 Agilent Technologies 2 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.

Copyright © 2010 Agilent Technologies 3 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

Copyright © 2010 Agilent Technologies 4 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 5 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

Copyright © 2010 Agilent Technologies 6 Message Formats Message Formats (Master/Slave Relationship) Example #1: BC to RT Transfers (BC sends data to RT) Note: Signals probed at BC input/output test plane A Packet - Command Word from BC to RTA = 0F w/ receive bit set: Get ready accept data. A A B Packets - 5 Data Words transmitted from BC to RT BBBBB BBB C Packet - Status Word from RTA = 0F: Got it! C C

Copyright © 2010 Agilent Technologies 7 Message Formats Message Formats (Master/Slave Relationship) Example #2: RT to BC Transfers (BC requests data from RT) Note: Signals probed at RT input/output test plane A Packet - Command Word from BC to RTA = 02 w/ transmit bit set: Send me data. A A B Packet - Status Word from RTA = 02: Here it comes! B B C Packets - 4 Data Words transmitted from RT to BC CCCC CCC

Copyright © 2010 Agilent Technologies 8 Message Formats Message Formats (Master/Slave Relationship) Example #3: RT to RT Transfers (BC requests RT 2 to send data to RT 1) Scope waveforms not available A Packet - Command Word from BC to RTA 1 w/ receive bit set: Get ready accept data. A A B Packet – Command Word from BC to RTA 2 w/ transmit bit set: Send data to RT 2. B B C Packet – Status Word from RTA 2: Here it comes! C C E E Packet – Status Word from RTA 1: Got it! E DDD D Packets - N Data Words transmitted from RT 2 to RT 1 DDDD Note: Signals probed at RT2 input/output test plane

Copyright © 2010 Agilent Technologies 9 Primary Electrical/Physical Layer Specifications Transformer CoupledDirect Coupled Terminal Output Specs Voltage Swing18 to 27 V p-p6 to 9 V p-p Overshoot 900 mV 300 mV Noise 14 mV RMS 5 mV RMS Transition Time100 to 300 ns (10/90) Zero Crossing Distortion 25 ns Output Symmetry< 250 mV< 90 mV Terminal Input Specs Voltage Swing0.86 to 14 V p-p1.2 to 20 V p-p Input Rejection V 0.2 V 0.28 V Zero Crossing Distortion 150 ns 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)

Copyright © 2010 Agilent Technologies 10 Measurement Test Planes Data Device Corporation Graphic 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.

Copyright © 2010 Agilent Technologies 11 The Problem: Most of todays scopes trigger on simple edge crossing conditions Simple edge triggering cant differentiate between transmitted and received words. External/synchronization signals are rarely available. Resultant measurements and display are composites of ALL words.

Copyright © 2010 Agilent Technologies 12 Required MIL-STD 1553 Triggering 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 Received signals at RT2 transmitted from RT3 Probe at RT2 Trigger on Status Words with RTA = 3 Transmitted signals at RT1 Probe at RT1 Trigger on Status Words from RTA = 1 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) 1

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 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 Triggering on MIL-STD 1553 Signals Note: The RTA + 11 bits trigger mode can be used to trigger on and differentiate between specific Command and Status Words.

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 Sub-address = 30 (decimal) Command versus Status Word Triggering Command Word Trigger Status Word Trigger Trigger: RTA + 11 bits = 02 HEX XXXXX Using the RTA + 11 bits Trigger Mode Trigger: RTA + 11 bits = 02 HEX + X 0X000 XXXXX Command Word Status Word Status bits Trigger Command Word Status Word

Copyright © 2010 Agilent Technologies 15 Measuring received signals at RT2 transmitted by the BC Rise Time & V RT input MIL-STD 1553 Trigger Setup (Command Word Trigger: RTA = 2, Transmit, Sub = 1110) T/R Sub-Address Command Word received from BC

Copyright © 2010 Agilent Technologies 16 Measuring received signals at RT2 transmitted by the BC MIL-STD 1553 Trigger Setup (Command Word Trigger: RTA = 2, Transmit, Sub = 1110) T/R Sub-Address Response Time

Copyright © 2010 Agilent Technologies 17 Measuring received signals at RT2 transmitted by the BC Intermessage Gap Time MIL-STD 1553 Trigger Setup (Command Word Trigger: RTA = 2, Transmit, Sub = 1110) T/R Sub-Address Intermessage Gap

Copyright © 2010 Agilent Technologies November 2007 Page 18 Vertically closing eye due to noise and/or insufficient signal level Horizontally closing eye due to jitter and/or signal timing errors Eye-diagrams display worst-case jitter, vertical noise, & signal anomalies. Conventional eye-diagrams measurements require a reference clock signal for triggering. MIL-STD 1553 signals dont supply an explicit reference clock signal. Generating MIL-STD eye-diagram measurements requires either a software- or hardware-recovered clock. 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.

Copyright © 2010 Agilent Technologies November 2007 Page 19 1.Scope triggers on specific word in order to capture and display input or output signals at a particular test plane. 2.Scopes timebase is scaled to repetitively capture just the 1 st Manchester-encoded bit (bit #4) for 50 milliseconds with infinite-persistence turned on. 3.Scopes timebase is scaled to repetitively capture just the 2 nd 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. MIL-STD 1553 Hardware Clock Recovery Algorithm Note: This is an automated test sequence that runs within the scope when a MIL-STD 1553 mask test file is recalled.

Copyright © 2010 Agilent Technologies November 2007 Page 20 Building the MIL-STD 1553 Eye Bit #4Bit #5Bit #6Bit #7Bit #8Bit #9 Bit #4 Bit #5Bit #6 Bit #7 Bit #8Bit #9 … Sync Field = Bits … Bits

Copyright © 2010 Agilent Technologies November 2007 Page 21 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 input test plane) and zero-crossing-distortion (+/- 150 input test plane) specifications. The MIL-STD 1553 Double Eye

Copyright © 2010 Agilent Technologies November 2007 Page 22 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. Summary

Copyright © 2010 Agilent Technologies Page 23 Agilents InfiniiVision Series Oscilloscopes SeriesBandwidthSample Rate (Max) Memory Depth MSODisplaySeg Mem Battery Option 7000B100 MHz to 1 GHz4 GSa/s8MYes 12.1 XGA YesNo 6000A100 MHz to 1 GHz4 GSa/s8MYes6.3 XGAYes 6000L100 MHz to 1 GHz4 GSa/s8MYesNoneYesNo 5000A 100 MHz to 500 MHz 2 GSa/s8MNo6.3 XGAYesNo MSO/DSO7000B MSO/DSO6000A DSO5000AMSO/DSO6000L Engineered for Best Signal Visibility Option 553: MIL-STD 1553 Trigger & Decode Option LMT: Mask Testing N2791A: 25-MHz Differential Active Probe

Copyright © 2010 Agilent Technologies Page 24 Application-specific Measurement Options for InfiniiVision Series Oscilloscopes MeasurementFactory-installed OptionAfter-purchase Upgrade MIL-STD 1553Option 553N5469A I 2 C/SPIOption LSSN5423A RS-232/UARTOption 232N5457A CAN/LINOption AMSN5424A FlexRayOption FLXN5432C I2SI2SOption SNDN5468A Mask TestOption LMTN5455A Segmented MemoryOption SGMN5454A

Copyright © 2010 Agilent Technologies November 2007 Page 25 Characterizing the Physical Layer of MIL-STD 1553 Differential Bus Networks

Copyright © 2010 Agilent Technologies November 2007 Page 26

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 Agilents InfiniiVision Series Oscilloscopes for MIL-STD 1553 Testing (Option ) Compatible models: All 5000, 6000, and 7000 series 4-channel DSOs and 4+16 channel MSOs Industrys 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 LMT 2 ) Entry-level Price: DSO5014A - $5300 Option $1300 Option LMT 2 - $ 700 N2791A Diff Probe -$ 600 Total System Price - $7900 Notes: 1.For after-purchase upgrade on an existing oscilloscope order N5469A. 2.For after-purchase upgrade on an existing oscilloscope order N5455A.

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 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) Sync (red) Manchester (red) Decode Lister Time-aligned Decode Trace Decoding the MIL-STD 1553 Bus

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 RTA Word Type 11 Bits16 Bits Word Type Command/Status Word Sync Data Word Sync Time-Aligned Decode Trace HEX Decode Binary Decode

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 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 Triggering on MIL-STD 1553 Signals Note: The RTA + 11 bits trigger mode can be used to trigger on and differentiate between specific Command and Status Words.

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 Sub-address = 30 (decimal) Command versus Status Word Triggering Command Word Trigger Status Word Trigger Trigger: RTA + 11 bits = 02 HEX XXXXX Using the RTA + 11 bits Trigger Mode Trigger: RTA + 11 bits = 02 HEX Command Word Status Word Status bits Trigger Command Word Status Word

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 Error Analysis and Triggering Parity Error Sync Error Manchester Encoding Error Manchester Encoding Error = Missing transition within bit time

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 Automatic Search & Navigation

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option 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:

Copyright © 2010 Agilent Technologies MIL-STD 1553 Option August 2009 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 Agilents N2791A 25-MHz differential active probe is recommended (US$600). Probing a MIL-STD 1553 Differential Bus