4Links Diagnostic SpaceWire Interface, Руководство пользователя, Страница: 27 / 47

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Additionally, these conditions may be made visible to the user program by being transferred in the usual data
stream using an extended character set - normally they would cause packet termination with an EEP. If visible,
they may also be time-tagged - see the Time-tag option.
We suggest that familiarisation with this feature is gained with the
SpWIO
program before using it from a C
program.
11 Option EW – Event/Error Waveforms
Option EW provides the ability to capture waveform traces of the SpaceWire signals when an error or a trigger
condition is observed on a link.
When option EW is installed in an EtherSpaceLink unit, each SpaceWire port incorporates a waveform recorder
that captures the wire signals at that port continuously. It stops recording and makes the waveforms available
after it is triggered by an event.
The EW option can also output a pulse on one of the rear-mounted SMA connectors, in response to a trigger.
F
IGURE
11-1 A
N
E
RROR
W
AVEFORM SHOWS A PARITY ERROR
(
AND THEN THE LINK TIMES OUT
)
Figure 11-1 shows an error waveform that was triggered by a parity error being observed on port 1 of a DSI. The
erroneous parity bit is shown in red. When the link engine detected the parity error, it
disconnected the link, and this may also be seen in the waveform.
An error waveform is displayed automatically by the
SpWIO
program when it is generated, and the pop-up
window allows the user to inspect the signal waveforms at various magnifications. It is also possible to save the
waveform to a file using the button provided.
When running a program that uses the C-language Application Programming Interface
Saved waveforms may be viewed using the supplied
waveform.jar
program: