I'm also an EE starting my PhD doing research in hardware/software co-design and circuit design. I'm also heavily interested in CS in general, so I'm planning to take as many CS courses as possible.

One thing I'm trying to do is keep myself current when it comes to software development. I think it's good to have a backup skill that I can fall back on in case my PhD doesn't work out.

It's good to know that someone like Dan Luu went through ups and downs before getting to where he is now.