I try to integrate https://github.com/NordicPlayground/nrf5-calendar-example into Keil project. But the following error messages shown when accessing NRF_CLOCK.
error messages
nrf5-calendar-example SOFTDEVICE: INVALID MEMORY ACCESS
source code
int main(void) {
_initVariables();
// Initialize.
log_init(); // Power_saving
uart_init(); // Power_saving
//_showInfo();
fstorageInit();
batteryVoltageInit();
timerInit();
button_events_init();
scheduler_init();
power_management_init();
ble_stack_init();
gap_params_init();
gatt_init();
db_discovery_init();
services_init();
advertising_init();
conn_params_init();
timerPeriodStart();
timerStart();
// SOFTDEVICE: INVALID MEMORY ACCESS occurred when running the following code
NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
NRF_CLOCK->TASKS_HFCLKSTART = 1;
while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
nrf_cal_init();
nrf_cal_set_callback(calendar_updated, 4);
}