We also used SDCC for teaching embedded devices. We deployed the compiled hex into simulation software called Proteus - it's a weird combination of schematic capture / pcb design / realtime circuit simulator supporting analog, digital and programmable components.

SDCC worked very well in this environment. Students could easily download it to work from home without any environment dependencies or license issues. Error messages were descriptive. Our customization needs were nicely solved by some compiler flags. All in all it was a good choice.

I did the same, for my college thesis project, back in 1998! It sure has been around for quite a while, glad to see it is still chugging along.