I Have attached my project which is an SDK 15. project, starting with the simple twi sensor project and including some functions calls from gpio from SDK 14.0, porting gpio from 14.0. The project does not compile correctly on account it can not see the function calls to the nrfx_gpiote.h file located in the modules folder. The port has utilized the function call of the 15.0 and does not utilize any defines between 14.0 and 15.0. I utilize the command line and armgcc makefile inside the pca10040 directory. Can anyone see a problem with the port and makefile edits? MPUsimpleTWI.zip