Sometimes you run into a few problems when developing your own hardware, and to solve these problems you have to build your own tools. This is exactly how [KC Lee]’s USB Packet Snooper was created. It’s a small device that allows for capturing and analyzing Full Speed USB traffic to debug one of [KC]’s other Hackaday Prize entries.
[KC] is building an HID Multimedia Dial for this year’s Hackaday Prize. It’s kind of like the Microsoft Surface Dial or the ubiquitous Griffin PowerMate that has been on the market for the better part of two decades. This multimedia dial is bitbanging USB with an STM8, which means [KC] needs a tool to capture raw USB packets.
The design of this USB Packet Snooper is split up into two parts. The first is either a dongle or a pass-through device that simply serves as a tap between a USB device and a USB host. The logging and analysis board attaches to this dongle, and uses a rather fast ARM microcontroller to listen in on USB packets and send everything over serial to a PC.
This is a rather novel device; V-USB is limited to Low Speed USB, and other USB capture tools are far out of reach of the hobbyist budget. Software solutions on a PC obviously won’t work because [KC] doesn’t even know if he’s sending valid USB packets. This is a great tool that finally brings hobbyist-level USB analysis up to Full Speed USB.