I normally release my projects using the same licence as any code I have used (eg if I've used your GPL library I will release the project as GPL and acknowledge you as the author)  however as far as I am aware all of the information in this design was gleaned from the datasheets of the products and public domain information and no code or design is knowingly used from any other project.

Any similarity to your code is therefore purely coincidental as I'm sure there are only so many ways you can write an SPI or UART function in C. I am therefore declaring Public Domain.

This means you can use the design or any part of it without any restrictions, acknowledgements or whatever, this also means you can use the information for commercial closed source projects too if you are so inclined.