Or, do I need to buy the full IDE?
The evaluation version of keil has some restriction, such as code space limitation.
Although it could be beneficial to buy the full IDE, you can get a lot of things working fine without it.
In the SDK we have focused on working within the code size limitations.
To clean things up, I'd be happy if you could evaluate the answer you have received and accept it if you feel it's sufficient. If not, it might be useful to expand your question a little and provide further information.
