Non-Intrusive PHY IP Core

With InvisiPHY® DapTechnology offers a unique IP solution that enables 1394 devices with a non-intrusive listen capability of 1394b bus activity. The technology is easy to add to any standard 1394 interface and opens a whole new world of “stealth”-like bus monitoring capabilities! InvisiPHY®-enabled devices are not participating in the bus arbitration and for that reason do not get assigned a node ID. Contrary to other implementations they are actually not part of the bus at all! And since InvisiPHY® is essentially a bus pass-through, input/output buffer delay as usually observed with optimized PHY silicon for reconditioning and therefore, retransmitting is no longer an issue. InvisiPHY® is a combination of signal integrity preservation techniques (an adequate impedance matched design is critical to providing the required “isolation” from the twisted pair lines) and a unique variation of a 1394 PHY layer device implemented as an IP core running in an Xilinx Virtex 4 FPGA. This solution is only available from DapTechnology!

Key Feature

• Compliant with IEEE1394-2002 (BETA)
• Supports 100(B), 200(B), 400(B) and 800(B) Mbps transfer rates
• Connects to standard 1394b Link Layer
• Requires bus pass-through connectivity
• FPGA implementation for PHY simulation (receive only)
• Analog front end comprising primarily off:
  • High voltage SMD capacitors
  • High Speed ESD clamp diodes
  • High Frequency Amplifiers with SIEGET Transistors
• No SW needed

Products

Implementation Example:

InvisiPHY-enabled devices are not participating in the bus arbitration and for that reason do not get assigned a node ID. Contrary to other implementations they are actually not part of the bus at all! And since InvisiPHY is essentially a bus pass-through, input/output buffer delay as usually observed with optimized PHY silicon for reconditioning and therefore, retransmitting is no longer an issue.

As a first application InvisiPHY technology was first successfully implemented and used in DapTechnology’s FireStealth® bus analyzer product. The possibility to non-intrusively monitor the bus under test gives an entirely new approach to the challenging task of dealing with a test system in the presence of a measurement instrument.

The graphic on the right illustrates how a 1394 test instrument affects the bus topology and the associated node ID assignments. And readers familiar with the nature of asynchronous messaging are aware what fundamental effects this can have on the message ‘routing’. As shown below the original messages will address different nodes if the destination node identifier in the message header is not modified correctly.

If the analyzer above was enabled with InvisiPHY then the topology on the left would not change at all, all transactions would be routed properly and the analyzer would still be able to recognize all bus transactions. Granted, many plug-and-play compliant device implementations are smart enough to handle such changing bus scenarios. But these services require overhead and, especially in closed systems with non-changing bus topologies, they are often missing. And when bus analysis or monitoring devices are added to the system then things suddenly get a bit messy. InvisiPHY offers a unique solution to this problem as the devices on the bus under test are entirely unaware of the connected monitoring devices and can resume their operation without further adjustments needed.

Besides its usage in data analysis instrumentation the InvisiPHY technology has turned out to be an extremely useful tool for the implementation of a non-intrusive monitoring device and can be used in any industry application such as aerospace flight monitors, automotive data recorders or industrial system loggers. DapTechnology will license the technology to interested partners and assist with adaptation for critical environments.