5 Real Time Counter

The Real Time Counter aims to provide an abstraction interface to Timer-type peripherals such as the Timer0/1/2 peripherals and their derivatives. It abstracts the true size of the Timer peripheral selected so that users can just specify the amount of time the abstracted timer will run. RTCounter operates like a 32 bit timer, combining the Timer peripheral counters (8 or 16 bits) and an overflow counter stored in the remaining bits. RTCounter is different from the normal Timer operation as instead of setting a period, RTCounter should always be set to maximum period of the selected Timer Peripheral. The RTCounter is part of the MCC Foundations Services Library that aims to further simplify the configuration of the different peripherals for the benefit of first-time users and those with a limited MCU programming background.

It is important to note The RTCounter Software Library uses structures and linked-list implementation to perform functionalities such as creating, adding, and deleting timers. The term "timer" that we will be referring to in this discussion is represented by a structure rtcountStruct whose members are shown below:

typedef struct rtcountStruct { rtcountcallback_ptr_t callbackPtr; void* payload; struct rtcountStruct* volatile next; uint32_t absoluteTime; } rtcountStruct_t;

The member callbackPtr with data type rtcountcallback_ptr_t is a function pointer that points to a function that handles the event that would be triggered at the end of the timer period, henceforth referred to as the callback function.

The void pointer payload contains the data that the user would like to pass along to the callback function.

The pointer next is a pointer to another timer structure that is the next in line to be run after this current timer expires.

absoluteTime The structure member absoluteTime holds the time or more accurately, the number of ticks the timer would count before this timer expires.