Having a function for long Delay

Sorry for that. I actually meant xxxmin or hour by the use of /. Didn't realize it actually meant divide in programing language.

the purpose of the delay_function_for_xxxmin should do nothing for xxx number of minute. Im trying to have a 15 min delay before I execute the next function. I also want to be able to change it to 30min if required.

Doing some research i found out that i can use UL after value of 320000 in delay. However i can see there is a time shift of 5 sec every 10 minute.

I was hoping to have a void function that uses RTC module which creates a delay of 15 minute or 30 minute when called.

Regards
Vishal