VirtualBreadboard
VirtualBreadboard electronic circuit components are modeled at the function block level and are wired together to create a real-time interactive circuit simulation representing the whole embedded application. Compared to other simulators many find the high level approach taken VBB easier to use and much faster to model and test out new ideas and circuit variations.
VirtualBreadboard was made free in early 2009 and is extensible through the OpenVBB API and the team is working to open the source of most of our component libraries for others to build on. These projects are available in the OpenVBB directory of the VBB release.
OpenVBB is a simulation framework for building function block components that can be wired together inside VBB. OpenVBB provides support for things like graphics, properties, and the simulation lifecycle.
Their official website : http://www.virtualbreadboard.net.