Additional functionality can be added to 4Links SpaceWire test equipment simply by changing the firmware memory card in your platform.
Diagnostic and other Options can improve the usefulness of many of 4Links' products while saving expense for users who do not need the capability of a whole extra unit. See below for a table of available options.
Extra Options may be purchased at the same time as the equipment, or later when the need arises. The installation of extra Options does not require the return of your product to 4Links.
The Options that are available for each product are:
|Diagnostic SpaceWire Interface||SpaceWire RMAP Responder||Flexible SpaceWire Router||Multilink SpaceWire Analyzer||Multilink SpaceWire Recorder||Absolute Time Interface|
|Time Code generator / distributor||TC||available||available|
|PPS Time Code||included|
Details of the individual options follow.
Event/Error Reporting (Option ER)
Normally, only data and EOP/EEP characters are seen in the ESL data streams. Other sequences and tokens or token-sequences are hidden, some because they cause error conditions and result in a link being reset (which might therefore generate an EEP character).
The ER option allows selected events to be seen by the user for diagnostic purposes. In the case of error events, further action may be taken in the DSI if the EI (Error Injection) option is also installed.
Events affected by this option include:
- when the first NULL or FCT arrives on a link that is trying to start;
- when a link fails to start;
- when a link disconnects;
- when ECSS time codes are received;
- when the number of flow control tokens received is inconsistent;
- when ECSS errors (i.e. ESC-ESC, ESC-EOP, ESC-EEP, Timeout, Parity error) are received.
Event/Error Waveforms (Option EW)
Each SpaceWire port has an associated waveform store that captures the transmit and receive wire signals for that port. The capture of a waveform will be triggered by a wide variety of events on that port. Each captured waveform contains:
- traces of the wire signals at the port;
- an indication of the event that triggered the capture;
- an interpretation of the signal waveforms as SpaceWire characters; and
- a time scale that can be used to correlate the event to time-tags in this, or other, 4Links SpaceWire units.
The waveform viewer software allows a waveform to be viewed at various zoom levels, and saved to a file.
Time Code generator / distributor (Option TC)
SpaceWire time codes may be automatically generated using the TC option at intervals between 10 microseconds and 999 seconds, or individually upon user request.
All eight bits of the time code value may be set, although the Standard recommends that the most significant two reserved bits be transmitted as zeroes.
Time-Tags (Option TT)
The Time-Tag option provides a free-running timer, with a resolution of less than 2ns, that can be recorded when a variety of events are observed:
- The first byte of a packet;
- Intermediate bytes of packets;
- The end of packet marker, EOP or EEP;
- All of the events recorded by the ER option, if fitted.
The same timer is used for all interfaces on an individual 4Links EtherSpaceLink family unit, allowing for the precise correlation of activities on several SpaceWire links to a resolution of better than one data bit period.
Customers with more than one DSI, MSR or SRR unit may synchronise the Time-Tag timers of these devices to that of their chosen master unit, to a resolution of better than 3ns. Thus, events recorded on any unit may be correlated together. This facility requires that all of the units be fitted with rear SMA connectors - see option "S" on the Hardware Platform Details page.
Owners of a 4Links Absolute Time Interface (ATI) may synchronise the Time-Tag timers in their other DSI, MSR and SRR units to the ATI's IRIG-B time source, providing time-of-day time-tagging of all events. It is straightforward with this option to identify SpaceWire traffic and error conditions at the time that a situation occurred, such as that from the system clock of the computer being used to generate satellite commands or to control an EGSE.
Event/Error Injection (Option EI)
The Event/Error Injection option, in the Diagnostic SpaceWire Interface, allows errors to be introduced into a data stream in a controlled manner:
- Parity error;
- Idle periods that may be set to exceed the timeout period.
Link behaviour may be changed in ways that produce both ECSS-conformant behaviour and non- ECSS-conformant behaviour:
- At link start, the number of flow control tokens sent may be set between 0 and 15 [only values from 1 to 7 conform to the ECSS standard];
- Automatic sending of flow-control tokens may be suppressed, leaving the user to send FCTs or not, as required - this allows links to be tested with a shortage of FCTs and with an excess;
- The link may be set so that data is transmitted regardless of whether there is sufficient flow credit.
Synchronized Outputs (Option SO)
For some applications, it is necessary to generate two or more signals closely aligned in time, or with controlled delays - such as testing arbitration in a routing switch. The SO Option provides this capability, aligning outputs closely or with controlled delays in multiples of 4 bit periods (e.g. 4*5 = 20ns at 200Mb/s). Delays may be introduced to test the timeout detection function of a SpaceWire link. One or several or all ports may be synchronised, each with its own delay.
Packet Statistics (Option PS)
The 4Links Multi-link SpaceWire Analyzer (MSA) and Flexible SpaceWire Router (FSR) products collect packet statistics, including the number of packets sent and received by each port, the maximum and minimum size of packets on each port, and the total amount of data seen.
PPS Time Code (Option PPS)
The Absolute Time Interface (ATI) enables all the 4Links test units in a test system to be synchronized to an accurate "Time of Year", so that timing measurements can be made with any number of units, all sharing a common time reference.
The ATI also has a single SpaceWire port which, on the basic unit, outputs a 1 pulse per second SpaceWire Time Code. Optionally, further Time Code outputs are available.
If you need more SpaceWire ports or several concurrently available functions, then your unit may need a more major upgrade (see the table on the Hardware Platform Details page), or you will need extra platforms, but they will all share the characteristics of your existing products.