Tools
Logic Analyzer
Helpful to analyze/debug data streams or measure ppm signal length.
saleae (works with linux)
The original costs about 120€, china clones begin at 10€.
The Seleae software for windows only allows their original hardware by setting the VID (Vendor ID) and PID (Product ID) in the saleae.inf file. This file is required as driver for the harware.
There is also an open source support for a lot of different logic analyzers (china clones) sigrok