Protocol-level debug test

Serial bus protocol test

Whether USB or CAN Bus decoding confirming that data is being transmitted correctly between the modules connected to each other by serial bus, and that the data content is as intended, is a part of developing and maintaining any system using serial buses for data communication via a serial peripheral interface; over distances as small as a few millimeters for PCIe interconnects on computer boards, up to the 1700 meters possible with 10BASE-T1L Ethernet for factory automation,

As the data communication is a series of events, oscilloscopes are best suited to investigating serial buses, primarily in the time domain. Both for debug and maintenance, two basic functions based on the protocol rules defined for a standard are required:

  • Trigger (and search) on protocol events
    The oscilloscope shall acquire the waveforms resulting from a selected bus event such as the start of a frame, frame ID, specified data content, or error conditions. Being able to use search functions to locate the part of the acquired waveform containing the trigger event quickly, greatly speeds any analysis.
  • Decode data
    Decode the binary values used to transmit data via a serial bus into a suitable protocol level for a man or machine to understand, such as alpha-numeric characters for plain text or hexadecimal values (for example) depending on the bus application.

Your serial bus protocol test challenges

You want to be confident that you have detected all the errors causing messages not to be transmitted correctly, and as quickly as possible.

You need to decode the message content to the suitable protocol level for analysis, whether this is machine-based or as a manual human task.

In bi-directional buses, you need to identify the direction in which a message is being transported.

Our serial bus protocol test solutions

The entire portfolio of Rohde & Schwarz oscilloscopes include serial bus trigger and decode software options, from the 50 MHz bandwidth 2-channel R&S®RTC1002 to the 16 MHz bandwidth 4-channel R&S®RTP. The protocols supported by each oscilloscope depend on whether its performance matches the individual protocol parameters such as bandwidth and data rate, and the amount of data to be decoded to make sense of its content and purpose.

The standards supported include;
I²C, SPI, UART, RS-232/422/485, 10BASE-T, 100BASE-T, MDIO, 8b10b, USB 1.0 – 3.1, USB-PB, USB-SSIC, PCIe Gen 1-3, CAN/LIN, CAN-FD, SENT, CXPI, 100BASE-T1 BroadRReach/Ethernet, 1000BASE-T1, MIL-STD-1553, ARINC 429, SpaceWire, MIPI RFFE, MIPI D-PHY v.1.2, MIPI M-PHY, Manchester, NRZ (configurable).

In many cases a test fixture is required to connect the device under test to the test instrument; Rohde & schwarz supply a wide range of test fixtures, including directional couplers to identify forward and reverse signals in full duplex standards.

As a test fixture has its own RF properties, these will affect the signal values measured. Rohde & Schwarz supply de-embedding functions to evaluate the impact of the test fixture on a test setup.

To sample a bus at locations throughout the device under test, Rohde & Schwarz supply all the necessary probes with a wide range of tips and other connectors, with high impedance and high bandwidth. The physical contact between a probe and the test point inevitably affects the electrical properties of the waveforms; Rohde & Schwarz supply functions to characterize and remove the influence of the probe from the measurements.

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Your benefits from our serial bus protocol test solutions

Find what you are looking for quickly and easily with powerful Search functions on the protocol layer most suited to your needs; from signal properties to selectable levels of data content.

Detect even short transient disturbances and errors in need of debugging. The hardware-based high-speed acquisition and fast refresh rate minimizes the signal blind time.

Only invest in trigger and decode functions for serial busses in which you are interested. Add additional bus technologies as you require them quickly and easily.

The complete test setup including probes and test fixtures is from a single supplier.

If you have any further questions regarding serial bus protocol test solutions, please contact us.

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