Debugging a SpaceWire Hardware Link Fault - STAR
Contents
1. 50 ns 270 ns Ons 50mS o PARITY ERROR 30 ns 30 ns ee PARITY ERROR 70ns 40 ns NCHAR 5F 120 ns 50 ns 140 ns 20 ns 840 ns 700 ns 880 ns 40 ns Character Display Packet Display Bit Stream Display Complete End A 0 000 Hz End B 0 000 Hz Search Character Display for Parity Error STAR Dundee SD_TN_004 a 6 SpaceWire Link Analyser Mk2 Debugging a SoaceWire Hardware Link Fault The packet display provides a packet level view of the captured data In this scenario we can see the link errors indicated by the red cell have affected two packets on End A one is missing an EOP marker and another is missing the packet header E SpaceWire Link Analyser Mk2 Serial Number 35100030 Not Saved File View Find Settings Trigger Help a xX p a o _Time From Trigger Time Delta End A Delta 3 360 us 50 ns 3 020 ys 340 ns 2 900 us 120 ns 2 830 us 70ns E Cargo Size 7 bytes 2 510 us 320 ns 2 370 Us 140 ns Header 82 2 300 us 70 ns Cargo Size 7 bytes 1 980 us 1320 ns 1 840 us 140 ns 1 790 ys 50 ns ize 7 bytes 1 470 ys 320 ns 1 270 us 200 ns 1 210us _ _ 60 ns 900 ns 310 ns 140 ns il 50 ns Cargo Size 7 bytes 320 ns 340 ns 50 ns Cargo Size 0 bytes2. 70 ns Missed Header Cargo Size 2 bytes 70 ns 700 ns 40 ns Cargo Size 320 ns bytes m Format Data View Bit Width Byte Settings Expand AIl k l J ASCII lt Integer 3 Bit Byte _ 32 Bit DWord Bytes Per Row Collapse All gt Protocol Hex 16 Bit Word 64 Bit QWord Character Display Packet Display Bit Stream Display Complete End A 0 000 Hz End B 0 000 Hz Packet Display The bit stream display provides a graph of the data and strobe signals captured on both SpaceWire links The screenshot of the bit stream display below shows the cause of the parity errors in this scenario Between the marker A the purple vertical line and marker B the orange vertical line a simultaneous transition is highlighted on the data and strobe signals on End A E SpaceWire Link Analyser Mk2 Serial Number 35100030 Not Saved File View Find Settings Trigger Help a xX gt he EN Zoomin a Zoom Out a Zoom All End A Data End A Strobe End B Data End B Strobe 4 b Character Display Packet Display Bit Stream Display Complete End A 0 000 Hz End B 0 000 Hz Bit Stream Display SD_TN_004 STAR Dundee SpaceWire Link Analyser Mk2 Debugging a SoaceWire Hardware Link Fault Inspecting these views and comparing expected SpaceWire link traffic with actual traffic helps trace the ca
3. Analyser Mk2 will allow the traffic to flow on the link between the equipment as before while allowing the traffic to be monitored unobtrusively as aE Application Software PC Link Analyser Mk2 SpaceWire Cable SpaceWire Cable O D n 4 D D D Por STAR Dundee STAR Dundee Router USB Mk2 Device Under Test Link Analyser Mk2 Connected Application Note SpaceWire Link Analyser Mk2 Debugging a SoaceWire Hardware Link Fault View Link Statistics Once connected launch the SpaceWire Link Analyser Mk2 software on the host PC The Link Analyser Mk2 immediately starts to record link statistics To view the link statistics open the Status Counters display This shows the number of errors and characters recorded and the current signalling rate This view can quickly show if the link is operating as expected i e the signalling rate is correct and the number and types of characters recorded are as expected It is also a good immediate indicator of link faults The screenshot below shows in this example parity errors have occurred on End A and a disconnect error on End A and End B The signalling rate is zero because at this stage the link has been disconnected The status counters display can help indicate errors or characters of importance that can be used to trigger the Link Analyser Mk2 and narrow the search for the fault see below for more on triggering Alongside the link statistics are graphs that illus
4. A j T STAR D ndee SpaceWire Engineering Excellence SpaceWire Link Analyser Mk2 Debugging a SpaceWire Hardware Link Fault The SpaceWire Link Analyser Mk2 is designed specifically to support the testing and debugging of SpaceWire systems This application note provides an example of debugging a SpaceWire hardware link fault using a Link Analyser Mk2 saving the engineer significant time and effort in the process Scenario During the development of a piece of SpaceWire equipment we need to debug a hardware problem with a SpaceWire link When the unit under test is connected to another piece of SpaceWire equipment we observe a link disconnect suggesting an error on the link For example the UUT may be connected to a STAR Dundee Router USB Mk2 in which case the disconnect is indicated by the link status LED flashing red Debugging with the Link Analyser Mk2 In this scenario the Link Analyser Mk2 is used to confirm that the link is operating as expected prior to the fault identify the type of errors occurring in the link and allow the specific error to be targeted to capture the trace at the time of the fault The trace can then be inspected for the cause of the fault The following sections describe how this can be done Test Setup Connect the Link Analyser between the two pieces of equipment using the two SpaceWire interfaces on the front panel Connect it to a host PC via USB The diagram below illustrates this configuration The Link
5. or occurs before the disconnect Therefore we need only reserve a small amount of memory to capture the trace post trigger to confirm the cause of the disconnect error is the parity error The majority of the memory is used to store the trace before the trigger to try and capture the cause of any faults ie SpaceWire Link Analyser Mk2 Serial Number 35100030 File View Find Settings alx gt Trigger Sequence ger Options Data Comparators Packet Count Comparator Timecode Comparator Character Enable External Trigger Op Trigger Options b Start Trigger Trigger Delay Stop Trigger od I Character Memory Trigger Position in EEE eee 20 40 60 80 100 Bit Stream Memory Trigger Position in 0 20 40 60 80 100 Cai End A 200 002 MHz End B 200 002 MHz Trigger Options STAR Dundee SD_TN_004 T SpaceWire Link Analyser Mk2 Debugging a SpaceWire Hardware Link Fault It is possible to enable and disable recording of specific character types Disabling the recording of one character type means more memory is available to those remaining enabled character types As disabled character types are not recorded it also means they are not present in the displays effectively filtering the character types For these reasons in this example NULL control code recording is disabled SpaceWire Link Analyser Mk2 Serial Number 35100030 File View Find Settings Trigger Help Soe femmes T OOO Trigger O
6. ptions Data Comparators Packet Count Comparator Timecode Comparator Character Enable External Trigger Options Character Enable Options gt Start Trigger Character Enable Stop Trigger C NULL Enable FCT Enable Data Enable Time code Enable Header Storage C Header Only Enable d e e End A 200 002 MHz End B 200 002 MHz Disable NULL Control Code Recording Analyse the SpaceWire Traffic Once captured we can inspect the SpaceWire link traffic using the character packet and bit stream displays The character display shows the characters events and errors captured In this trace we can see the trigger has occurred on the parity error as setup in the trigger sequence There are a number of indicators of this in the Time From Trigger column the Time From Trigger value equals zero the cell is outlined in red representing a marker and the column background colour is red blue indicates before trigger red after This is shortly followed by disconnect errors on both ends of the link confirming the cause of the disconnect is a parity error introduced by the unit under test SD_TN_004 T STAR Dundee SpaceWire Link Analyser Mk2 Debugging a SoaceWire Hardware Link Fault SpaceWire Link Analyser Mk2 Serial Number 35100030 Not Saved File View Find Settings Trigger Help aja x gt B Time From Trigger _Time Delta End A Event End A Error End A Delta End B E
7. s led to the disconnect therefore it may be useful to trigger on a character sequence error escape error credit error parity error disconnect error or all errors The status counter display has however already indicated the cause of the disconnect as a parity error on End A To confirm this we want to analyse the link traffic surrounding the parity errors The trigger is set to occur when a parity error is detected on End A as shown below In this example the trigger is set to occur when a single event is detected as there is no need to do anything else We can however configure the trigger to occur when a complex sequence of multiple different events is detected SD_TN_004 STAR Dundee SpaceWire Link Analyser Mk2 Debugging a SpaceWire Hardware Link Fault E SpaceWire Link Analyser Mk2 Serial Number 35100030 File View Find Settings ee a e x gt o Monsma __ Trigger Options Data Comparators Packet Count Comparator Timecode Comparator Character Enable External Trigger Tigger Sequence Options gt Start Trigger Stop Trigger Trigger Sequence Ca Leen End A 200 002 MHz End B 200 002 MHz Trigger on Parity Error The Link Analyser passively buffers the SpaceWire traffic on the link in anticipation of the trigger When the trigger occurs traffic before and after the trigger is captured The memory reserved for before and after the trigger is configurable In this example it is known that a parity err
8. trate the character and error activity over time In this example we see data EOP FCT and NULL characters represented by the blue salmon cyan and light grey lines are flowing in both directions of the link up until a disconnect error occurs on End A and End B represented by the red line E SpaceWire Link Analyser Mk2 Serial Number 35100030 Lo es File View Find Settings Trigger Help a Status Counter Display i ho E Status Counters Characters Events Total x EndA EndB Signaling Rate 0 000Hz _ 0 000Hz Disconnect Error i i i Parity Error i as a Credit Error i e Escape ooo a Ss Char Sequence Ero i i iT Data Character 302 712 736 EOP Character 37 839 093 37 839 092 EEP Character i FCT Character 42568979 NULL Character 584 141 013 584 140 980 Time code Character 0 B v Draw Errors On Graph Clear Resume Idle End A 0 000 Hz End B 0 000 Hz Status Counter Display Capture the SpaceWire Traffic In order to view and debug the SpaceWire traffic between the two pieces of equipment we must first capture it SoaceWire link traffic is captured when a user defined trigger sequence is detected on the link The trigger can be configured to occur on a range of different events including time codes data characters control characters and errors In this scenario we want to identify what error
9. use of SpaceWire link problems In this example the character display has confirmed the cause of the disconnect is a parity error the packet display has shown those packets affected by the errors and the bit stream display has shown the parity errors are a result of a simultaneous transition Conclusion When debugging a SpaceWire hardware link problem using a Link Analyser Mk2 allows the engineer to inspect the link traffic target specific event sequences and filter information and therefore enhances their ability to solve the problem quickly and efficiently In this application note we have seen how the Link Analyser is connected and how to set a trigger to capture SpaceWire link traffic at the most appropriate time Once captured the Link Analyser s displays let us inspect and debug the traffic flowing in each direction at the character packet and bit stream level This document only briefly describes some of the Link Analyser s capabilities in relation to a specific problem The Link Analyser Mk2 is provided with context sensitive help and a user manual that comprehensively describes the Link Analyser Mk2 For more information please visit our website at www star dundee com or contact us at enquiries star dundee com STAR Dundee STAR House 166 Nethergate Dundee DD1 4EE Scotland UK _Tel 44 1382 201 755 Fax 44 1382 888 838 Email enquiries star dundee com Web www star dundee com
10. vent End B Error End B Delta 1 070 us 40 ns NCHAR 47 40ns NULL 40ns 1 020 us 50 ns A BE 50 ns 970 ns 50 ns C 50 ns 920 ns 50 ns ICI 39 50 ns 900 ns 20 ns JP 20 ns 850 ns 50 ns 760 ns 90 ns 710 ns 50 ns 660 ns 50 ns 610 ns 50 ns 560 ns 50 ns 510 ns 50 ns 460 ns 50 ns 400 ns 60 ns De m4 r m4 t De pan 12l NQAQaAQqaQqaaQqn mm a m4 320 ns 70 ns 140 ns 50 ns 270 ns 270 ns Ons J50ns PARITY ERROR 50 ns 30 ns 30 ns PARITY ERROR 30 ns 70ns 40ns ICHAR 5F 40 ns 120 ns 50 ns ICE 50 ns 840 ns 700 ns 700 ns 880ns 40 ns JE 40 ns 930 ns 50 ns 50 ns 1 040 us 50 ns A 50 ns 1 090 us 50 ns 50ns 1 130 us 40ns ICE 3 40ns 390 ns 10 ns 140 ns 20 ns 20 ns 990 ns 60 ns 9 60 ns 1 180 us 50 ns ICHAR 96 50 ns 1 200 us 20 ns EOP 20 ns 1 270 us 70ns DISCONNECT 1 660 us 1 810 us DISCONNECT 1 880 us Character Display Packet Display BitStream Display Complete End A 0 000 Hz End B 0 000 Hz Character Display In this scenario the parity error has already been identified as the cause of the disconnect but in a different scenario it may not be immediatel
11. y obvious what the problem is The Link Analyser software can display up to one million events and so searching for problems manually can be time consuming To save time and effort the character display has a search feature to aid navigation and debugging that can be used to find specific events and errors i SpaceWire Link Analyser Mk2 Serial Number 35100030 Not Saved File View Find Settings Trigger Help a b Search Character Display amp Search Packet Display DETA A Event End A Error End A Delta End B Event End B Error End B Delta Time From hgge 1 590 us 50 ns NCHAR E1 50 ns 1 540 us 50 ns 200 ns 50 ns 1 480 ys 60 ns Lar o d F a 60 ns 1 470 us 10 ns Search Character Display 10 ns 1 210 us 60 ns 1 270 us 90 ns Evens Somess 200 ns 1 360 us 110 ns 1 170 ys 40 ns T 4 110 us PEES All Errors NChar Sequence L Escape EOP 1 070 us 40 ns IC Parity Error C EOP Sequence _ Escape EEP ous Tx Credit Error 920 ns 50 ns IC Rx Credit Error 900 ns 20 ns 850 ns 50 ns 760 ns 90 ns 710 ns 50 ns 660 ns 50 ns 610 ns 50 ns 560 ns 50 ns 47 510 ns 50 ns 8E 460 ns 50 ns K 1C 400 ns 60ns ICHAR 39 390 ns 10 ns 320 ns 70ns EEP Sequence C Escape Escape Time Code Sequence Disconnect
Download Pdf Manuals
Related Search