Read and write schedule (enhancement)

[Eugen4]

Installation specifics

• Heating type: Vitotronic 200
• Protocol: P300
• Board: ESP8266 (Wemos D1 mini)

Symptom

What happens? I wasn't able to read and write schedule for water heating
What would you expect? Add function to the library for simplify read and write schelude info to Viessmann

Extra info

ESPHome provides such possibilities:
Schedule plans info: https://deploy-preview-2737--esphome.netlify.app/components/optolink.html#schedule-plans
Code reference: https://github.com/80morpheus/esphome_optolink/blob/optolink/esphome/components/optolink/helpers.cpp

Some usefull info from here openv/openv#282

 * ## Unit: CycleTime
 * Desc: 1 byte coding of the switching times.
 * The switching times are divided into 10 minute steps and coded
 * this saves space.
 * The upper 5 bits represent the hours, the lower 3 bits the number
 * share of 10 minutes
 *
 * MSB LSB
 *      +---+---+---+---+---+---+---+---+
 *      | h4  h3  h2  h1  h0 | m2-m0 * 10|
 *      +---+---+---+---+---+---+---+---+

[bertmelis]

Can be implemented. Could you remind me in a week or so? I'm enjoying some time off 🎄.

[bertmelis]

I don't use this feature myself so I'm not really familiar with the schedule.

A single schedule is encoded by a series of 8 bytes with each byte representing a time (rounded to 10 minutes). So for one day you can define 4 periods (time on + time off = 2 bytes). A whole week needs 7 * 8 bytes = 56 bytes, as referred to on the Home Assistant page.

I don't know if a single time entry can be read or written or the whole schedule (56 bytes) need to be requested.

So my main question: How would you use the schedule?