The accompanying code to this application note enables easy reconfiguration of the sample period. In order to change it from the default value of 30 seconds, all that needs to be done is change the hash define "SAMPLE_PERIOD" at the top of the main file. This value can be changed to any value between 1 and 65535 seconds (more than 18 hours).
If an ATtiny817 Xplained Mini is being used, change the hash define "MINI_BOARD" from "false" to "true". This affects the LED output pin and the clock source for the RTC.