The SSnoop testbench module is used to examine serial SpaceWire Data & Strobe signals and report the results to a file. The SSnoop module can be used in as either a standalone (half duplex) examiner or connected to another SSnoop module to create a combined (full duplex) examiner. A simple block diagram for the testbench module is shown below.
The difference between the two operating modes is in what is reported to the file. When operating in full-duplex mode the report files contain not only character information, but also latency information about the NChar's and what FCT's they are related to. A simple block diagram for the testbench module operating in full-duplex mode is shown below.
The SSnoop testbench module works by intelligently tracking the characters transmitted from a CODEC. By using knowledge of the ECSS-E-50-12A specification, the module makes an assessment of the CODEC, and attempts to determine from its transmissions if it is behaving correctly.
Numerous things are checked and reported by the testbench module such as:-
- Coincident D/S Transitions
- Disconnect Errors
- Parity Errors
- Escape Errors
- Time-Out Errors
- Flow Control Errors
- Character Errors
- State Changes
- Characters Transmitted
- Transmitter Frequency
An example half-duplex report file showing one of our SpaceWire CODEC's connected in loopback mode (Serial Tx to Serial Rx) is available here
An example full-duplex report file showing the the same operation is available here