Workflow

1.
Initialize system.
```
system_init();
```
2.
Configure and enable module.
```
configure_rtc_count();
```
3.
Create a RTC configuration structure to hold the desired RTC driver settings and fill it with the default driver configuration values.
```
struct rtc_count_config config_rtc_count;
rtc_count_get_config_defaults(&config_rtc_count);
```
Note: This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.

Alter the RTC driver configuration to run in 16-bit counting mode, with continuous counter register updates and a compare value of 1000ms.

config_rtc_count.prescaler           = RTC_COUNT_PRESCALER_DIV_1;
config_rtc_count.mode                = RTC_COUNT_MODE_16BIT;
#ifdef FEATURE_RTC_CONTINUOUSLY_UPDATED
    config_rtc_count.continuously_update = true;
#endif

Initialize the RTC module.

rtc_count_init(&rtc_instance, RTC, &config_rtc_count);

6.
Enable the RTC module, so that it may begin counting.
```
rtc_count_enable(&rtc_instance);
```

Configure callback functionality.

configure_rtc_callbacks();

7.1.

rtc_count_register_callback(
        &rtc_instance, rtc_overflow_callback, RTC_COUNT_CALLBACK_OVERFLOW);

7.2.

Enable overflow callback.

rtc_count_enable_callback(&rtc_instance, RTC_COUNT_CALLBACK_OVERFLOW);

Set period.

rtc_count_set_period(&rtc_instance, 2000);