Question: In EE all we need to draw some waveforms to ask or answer questions.

Is this could be done with TeX? Or what are the software's you people are using?

Could we have add some tools to draw waveforms in here?

Answer: 
This indeed is possible with LaTeX using the [`tikz-timing`](http://www.ctan.org/pkg/tikz-timing) package. It isn't included in the markdown editing though. But this might be possible..? It would be really useful, the `tikz-timing` is used by every professional organization to draw logic diagrams in datasheets, application notes, etc...
Some timing diagram answers were listed [in this question](https://electronics.stackexchange.com/questions/3564/software-to-create-timing-diagrams). [TimingDesigner](http://www.timingdesigner.com/Docs/TD_datasheet.pdf) and [TimeGen](http://www.xfusionsoftware.com/purchase_timegen.html) were mentioned. Another is TimingDiagramer.