I use one of the best diagramming software from Microsoft i.e. Visio to create different types of diagrams. You can give a try for creating the diagrams by using Visio and see whether it works it for you or not.
WaveDrom is Free and Open Source online digital timing diagram editor that uses JavaScript?, HTML5 and SVG to render WaveJSON input text description into vector graphics.
The project is in progress. Any feedback appreciated.