Example of what happpens inside the Cortex-M 4

Hello i am a student at cphbusiness in Denmark, and i am currently doing a research project on the Cortex-m 4. 
i am hoping someone can help me understand what exactly is going on inside the processor. I have attached a picture, and i am hoping someone can tell me with an example, what happens in the different parts when the processor is given "a comand" 

eg. when a smart bulb changes color, what happens inside the processor to do this?

thank you 

- Frederikke 

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