For an alarm clock I am trying to have the interface in HTML and CSS and I need the GPIO pins for PWM-output (3 channels and some digital, possibly also "analog" inputs). I want a neat web-interface, where I can set the alarm for some days and another alarm for other days of the week. I guess with CSS and HTML5 this is an easy/clear task from the web-perspective.
However, I wonder how I 1) establish the alarm feature: do I need a RTC clock or can I do this conveniently from the Raspberry system clock? And 2) how do i best interface the web-frontend with python (I know python, but not PHP) to access the GPIOs and other features of the Raspi? For this I found Flask and remi. It seems to me the former is more separated and uses the full potential of both worlds.
How do I best achieve 1) the alarm feature? And 2) is Flask a good option for me?
edit: I use an Raspi Zero W, so I have wLan and Internet (hopefully at all times). And I use a standing powersupply - in case the connection is dead it should resync, but otherwise I want the webserver for the interface to run 24/7.
I just wonder how I should implement the alarm itself. In the future I want to upgrade to a RTC. But for now I want to do it quick. But polling seems very bad - also I don't know how to poll in the flask context. It seems, that Flask just calls python, whenever a specific website-part is requested.