First off - you applied for a principal engineer position, despite apparently being unqualified for the role. Then, you not only did not take a senior position, you took an entry level position.
So - you may have a more than slightly inflated image of your own self-worth.
OR, you may be amazing, in which case your company may be taking advantage of you. If you are performing at a senior level, at the very least, after a full year, you should see a significant raise.
So, what to do?
Again - you need a reality check. So, go and apply for some senior engineer positions at good companies in your area and see if you get offers. If you do, then hey, you're a senior engineer! Bam. If not, then, well, you got your reality check anyway, and you can talk to those companies, as well as yours, about what they feel like the gap is between your performance and that of a senior engineer.
Good luck.ANSWERS： As others have pointed out, you might need "a reality check". However I am going to assume you're not entirely headstrong and foolish (you settled for less than a "principal engineer" position), and you're not entirely a sheep (you're not entirely willing to wait to get promoted until the company, in all its infinite wisdom, decides you've "earned" it, without questioning when, why, and how much).
If you've been there a year and they haven't given you a raise or promotion:
Make sure your manager knows your concerns and that you think it is reasonable that you get a raise and promotion at this time. Find out exactly what things they believe are a gap between your abilities and experiences and that title. If it is a concrete set of things, fill that gap immediately, show you've done it, and then then you have the leverage you need. If it is a number of years thing, leave your company now, as it isn't a fit for your expectations (very fast career growth rather than a career on rails). ... Well, interview at 4 or more places first, and land at least 3 offers so you can see what you are comparing to.
Unless there are reasonable gaps that your manager brings up, then consider that another company will give you both the promotion and raise you are seeking, as long as you state those as requirements of joining, and interview successfully for your target position.
If you have been there less than a year, and they didn't tell you up front there would be an X day or Y month probationary period that you've already passed:
Companies tend to deliver the salary that they intend to in the beginning. They give large raises to extraordinary people, not people who are just satisfactory, unless they give a promotion at the same time. Even then, they typically only give them once a year at the max, unless you do some crazy feat or demonstrate some very specific criteria outside the bounds of their typical employee review period.