Change target MCPU

You can change the target CPU of the project by the CPU type (-mcpu) option from the menu Project  Properties  C/C++ Build  Settings  Tool Settings.

ide project mcpu
Fig. 1. CPU type (-mcpu)
When you did change the CPU

Do not forget to update all other CPU type related settings and files as linker script, CPU register headers, CPU related symbols, or CPU specific compilator options defined within the miscellaneous options.