MICROPROCESSOR AND MICROCONTROLLER

Detailed explanation-1: -R14 is also called the Link Register (LR). This is used for holding the return address when calling a function or subroutine. At the end of the function or subroutine, the program control can return to the calling program and resume by loading the value of LR into the Program Counter (PC).

Detailed explanation-2: -A link register (LR for short) is a register which holds the address to return to when a subroutine call completes. This is more efficient than the more traditional scheme of storing return addresses on a call stack, sometimes called a machine stack.

Detailed explanation-3: -Register r14 is the subroutine Link Register (LR).

Detailed explanation-4: -On an ARM Cortex M series device, the link register (LR or R14) is a core register that stores the return address, such as when making a function call. In the case of an exception, the return address is pushed onto the stack by hardware and the LR is set to EXC RETURN (0xFFFFFFF1, 0xFFFFFFF9, or 0xFFFFFFFD).