Starting with Keil MDK version 5.37, the is no longer included by default. To use it, you must download it as a standalone "add-on" and manually register it within the IDE. 1. Download Arm Compiler 5
AC5 has reached "End of Support." No further updates are planned.
Choose a dedicated directory (e.g., C:\Keil_v5\ARM\ARMCC_506u7 ).
armcc -c --cpu=Cortex-M4 --c99 -O2 -I./inc -o main.o main.c
Once you have the installer, follow this process to avoid common pitfalls.