Ever since OH 1.6 (and before) setting an alarm clock in OH has been troublesome. We used to have to go to great lengths to set it up and expose it on our sitemaps with one Item each for the year, month, day, hour, and minute with rules to trigger when any of them change to construct a DateTime out of them and eventually to set a timer. Search for “Alarm Clock” and you will find many tutorials with different variations on this theme.
Now in OH 3 we have options to make this much simpler and more flexible.
Thus tutorial is focused mainly on the use case where the ability to update an item with the next scheduled alarm on the Android app. It can be expanded relatively easily to support more use cases.
Create a.DateTime Item called
AlarmClock. Configure this Item to be populated with the date and time of the next alarm. This can be done any way you choose. Options include:
In the Android app open settings and scroll down to “Send device information to server” and enable “Alarm time”, using “AlarmClock” as the name of the Item.
Link the Item to an Astro Channel to have the alarm be relative to a sun or moon event.
Create a Rule to update the time of the alarm based on some openHAB event.
Manually enter the date and time on MainUI. If using this approach, create a rule to advance the date of the alarm time to the current day.
Populate the Item based in calendar entries and the iCalendar binding.
If using manual entry, add the following as a custom widgets under Developer Tools. Then select the widgets as the Default Standalone Widget and Default List Widget in the
AlarmClock’ Item’s metadata. See the following for more details:
- OH 3 Examples: How to boot strap the state of an Item
- OH 3 Tips and Tricks - #2 by rlkoshak
- Example Custom List Widgets
Then add a rule to advance the alarm clock time to the next day at midnight which will retrigger the creation of the alarm clock timer.
For use on custom Layout Pages
uid: datetime_standalone tags:  props: parameters: - description: Label for the widget label: Label name: label required: false type: TEXT - context: item description: An item to control label: Item name: item required: false type: TEXT parameterGroups:  timestamp: Jul 27, 2021, 10:06:53 AM component: oh-input-card config: outline: true clearButton: false inputmode: text footer: =items[props.item].state item: =props.item placeholder: mm/dd/yyy, --:-- -- title: =props.label type: datetime-local sendButton: true
For use in the Locations, Equipment, Properties, and inside List Card Widgets.
uid: datetime_list tags:  props: parameters: - description: Label for the wiodget label: Label name: label required: false type: TEXT - context: item description: An item to control label: Item name: item required: false type: TEXT parameterGroups:  timestamp: Jul 28, 2021, 9:01:20 AM config: outline: true inputmode: datetime-local subtitle: =items[props.item].state name: alarmtime label: =props.label placeholder: mm/dd/yyy, --:-- -- title: =props.label type: text sendButton: true
The above should handle daylight savings but has not been tested. One minute after midnight move the AlarmClock Item’s state to the same time but with today’s date.
Sometime soon we will have a marketplace for rules. In the mean time you need to copy and paste. Follow the instructions to install the rule found at openhab-rules-tools/alarm_clock at main · rkoshak/openhab-rules-tools · GitHub.
At a high level:
- create a new rule
- open the code tab
- copy the contents of alarmclock.yml on github to that code tab
- manually run the rule to create the timer; be sure to run it manually every time you modify this rule.
- on the Scripts page create a new Script using “alarm_script” as the UID
- select any language desired and write the code that should run when the alarm goes off
The rule in alarmclock.yml handles all the processing of changes to the
AlarmClock Item and creating and managing the timer. When the timer goes off at the
AlarmClock time, it will run your
By separating this into two parts it allows the user to code the stuff to do when the alarm goes off in the script language of their choice. It also allows the user to make modifications to the code that runs when the alarm goes off without needing to remember to manually rerun the rule to reschedule the timer. Finally, it provides a way to upgrade the library code without requiring users to update their custom code to install the updates.
Note, if using text based .rules files, the UID of your rules will be the name of the file followed by a one-up number based on the order of they appear in the file. If using text based rules be sure to update the alarmclock.yml imported rule to use the appropriate rule UID. If using some other language, review MainUI’s list of rules to find the UID for the rule to run and update as appropriate.
Here are some ideas for expansion and customizations:
Instead of using
AlarmClock, use one of the Items used in Time of Day so the day starts when the alarm goes off instead of a fixed time or Astro time. Be sure to update the trigger on the rule if a different Item is used.
Update the rule to handle more than one
AlarmClockItem, such as one per day. To do this add each DateTime Item to a Group and trigger the rule when a member of the Group changes. Iterate through the members of the Group and create a Timer for all the Items that have a DateTime for the future. As an added bonus add the UID for the Script rule to run as Item metadata so each alarm can do something different.
Use ephemeris to choose between two or more different alarm scripts based on the type of the day. For example, run one Script rule on weekdays and a different one on weekends and holidays.