I will list the links and learning material to get started on the UCD3138 firmware development :
Initial documents to read:
1) Datasheet : http://www.ti.com/product/UCD3138/datasheet
2) The next document to keep is the Technical reference Manual . It is not necessary to go through the document completely by keep this in mind whenever there is a question .
UCD Firmware development environment :
1) The firmware development for the UCD family happens with the help of two software's . The first is the TI’s Code Composer Studio. The recommended version to download is 6.1.3.00033. This can be downloaded here : http://processors.wiki.ti.com/index.php/Download_CCS
2) The recommended version of the compiler is ARM 5.2.4.
Steps on how to change the compiler version : https://e2e.ti.com/support/power_management/digital_power/f/184/t/611874