Volatile is a keyword to specify the compiler that this variable VALUE can change any time, so compiler should always read its value from its address, and not to USE temporary registers to STORE its value and use in later PART of the code. This is especially important to handle the memory mapped registers which are mapped as some variables or structures in embedded systems, such as hardware status registers etc, whose value can be changed anytime, depending on the hardware state.

Examples of volatile variables are,
• Hardware registers in peripherals (for example, status registers)
• Non-automatic variables referenced within an interrupt service routine
• Variables shared by multiple tasks in a multi-threaded application

Volatile is a keyword to specify the compiler that this variable value can change any time, so compiler should always read its value from its address, and not to use temporary registers to store its value and use in later part of the code. This is especially important to handle the memory mapped registers which are mapped as some variables or structures in embedded systems, such as hardware status registers etc, whose value can be changed anytime, depending on the hardware state.

Examples of volatile variables are,
• Hardware registers in peripherals (for example, status registers)
• Non-automatic variables referenced within an interrupt service routine
• Variables shared by multiple tasks in a multi-threaded application