You can use the Talking Reminders in Text Speaker. Talking reminders are used to read out loud any message at a scheduled time.

To add a reminder, click on the ‘Talking Reminders’ option from the tool bar. Then click on the ‘Create’ button to schedule the reminder. Enter your message in the text field. Configure the start date and time. Select the option to repeat the message and set it for 30 minutes.

The message will be read aloud every 30 minutes.