| Electronics > Projects, Designs, and Technical Stuff |
| ezSniffer - Hardware USB Packet Sniffer on a Budget |
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| TimCambridge:
I have cooked up a $79 USB Packet Sniffer that's an add-on for the FX2LP boards that you can get for a few dollars on ebay and similar sites. FX2LP boards are also sold as Ez-USB or CY7C68013A boards. You can get the marketing pitch at bugblat.com/products/ezsniff/, here is some technical info. How does it work? Essentially the ezSniffer is a special purpose logic analyzer. An on-board FPGA samples the USB signals, compresses the samples, and sends the compressed data to an analysis PC via the FX2LP's buffered high speed USB link. Software on the analysis computer decompresses the samples and puts up the pretty pictures. What can it sniff? Full Speed USB devices of course, but also High Speed devices. All High Speed USB devices start off at Full Speed, then negotiate a change up to High Speed. The ezSniffer prevents the change up. How deep is the buffer? For the compressed samples it is up to 4GB in theory, though we have not tested that deep, current software sets a 256MB limit. If your main concern is the configuration packets 16KB of compressed data is usually enough. There's lots more - disconnect/connect so that you can sniff the configuration packets, you can save the data and play with a python interface, you can even write protocol decoders in Lua.... I'll do my best to answer any technical questions here. |
| magic:
What's wrong with sigrok? I've never used it for USB but it supposedly supports it and 24MHz sampling may just barely do it :-// |
| NiHaoMike:
How does it compare to a Beaglebone Black? |
| TimCambridge:
--- Quote from: NiHaoMike on June 24, 2019, 05:47:31 pm ---How does it compare to a Beaglebone Black? --- End quote --- As I understand it, a solution with a BBB or any of the other similar systems works by programming the BBB to relay USB packets from a device port to a host port. On the ezSniffer the device/host connection is fixed hardware. Getting the BBB set up when you are struggling with a configuration problem is not for the faint hearted. Once any USB configuration issues are addressed the BBB comes much more into its own. |
| TimCambridge:
--- Quote from: magic on June 24, 2019, 12:59:00 pm ---What's wrong with sigrok? I've never used it for USB but it supposedly supports it and 24MHz sampling may just barely do it :-// --- End quote --- Sigrok can be an excellent solution if you can install the USB support and it works for you. The ezSniffer has a few advantages - easier setup, USB disconnect/connect for inspecting and debugging configuration packets, easier connection to the USB target, and supporting high speed devices. |
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