Eye diagrams are added to serial trigger and decode options
Serial data analysis capabilities for oscilloscopes are expanded with the addition of eye diagram capabilities by Teledyne LeCroy.
The company claims that it is offering the widest range of trigger, decode, measure or graph and eye diagram and physical layer options.
Users can isolate events using the serial bus trigger, and view colour-coded protocol information on top of analogue or digital waveforms. Timing and bus measurements allow quick and easy characterisation of a serial data system, says the company. Measurement data can be graphed to monitor system performance over time. Identify physical layer anomalies with eye diagram mask testing and mask failure locator.
An eye diagram of a packetised, low-speed, serial data signal can be rapidly displayed without additional set-up time. Eye parameters can quantify system performance and apply a standard or custom mask to identify anomalies. Mask failures can be indicated and can force the scope into stop mode.
Up to four serial data signals can be decoded and displayed as eye diagrams at one time. These can be different protocols, or the same protocol measured at different points (e.g. transmits and receive, different nodes, or different standard-defined test points). It is also possible to apply a user-defined filter to each eye diagram to display specific signals in the eye.
The signal quality of physical layer can be qualified in the eye by applying parameters for eye height, eye width, and number of mask failures. Some packages (e.g. FlexRay TDMP) include additional measurements defined in the standard.
A user-defined or pre-defined mask may be added to the eye diagram to evaluate if the physical layer signal intrudes too far into the eye opening. Applying a filter to include or exclude specific messages from the eye to determine failure source (e.g. messages from a specific node or with a specific ID). Mask failures are indicated with a red circle and can be displayed in a table. Touching the failure table opens a zoom of the failed area for further inspection.
Some standards, due to their speed or nodal complexity, provide specific guidance on what eye diagrams or measurements should be made and exactly how they should be performed. FlexRay and MIPI DPHY are examples. In these cases, the eye diagram capability is augmented with additional, specialised physical layer measurements, as per the standard.
The eye diagram is available for I²C, SPI, UART RS-232, CAN, CAN FD, FlexRay, LIN, ARINC429, MIL-STD-1553, USB 2.0, 8b/10b, LPDDR2, DDR2, DDR3, D-PHY/CSI-2/DSI, M-PHY and NRZ standards.