"PDF"s are not a really suitable format to put in a posting here to illustrate your project as they are not directly rendered in the Web page and tablets/ phones may not be able to render them at all. Of course you may link to them as datasheets and the like, but not to illustrate your project.
Post photos as images, but anything that comprises text, such as your code or serial monitor output, should be posted as text or in the case of code and extensive listings, using the "code" mark-up so it can be conveniently scrolled.