Extend timer randomization window

[Andreas-Marx]

The distinction of timer randomization windows [-14,+14] and [-15,+15] seems insignificant. We can make better use of the 4 bits in Timer.window by employing a kind of exponential scale:

• 0x0: +/- 0
• 0x1: +/- 1
• 0x2: +/- 2
• 0x3: +/- 3
• 0x4: +/- 4
• 0x5: +/- 5
• 0x6: +/- 7
• 0x7: +/- 10
• 0x8: +/- 15
• 0x9: +/- 20
• 0xA: +/- 30
• 0xB: +/- 40

If an Off-Command is scheduled within 79 minutes of the corresponding On-Command and both use window +/- 40, the On may be executed after the Off, leaving the switch on. To safely allow large randomization windows for short intervals, we reserve some codes to effectively carry over timer_window[index] from timer_window[index-1] and apply some additional randomization to it.

• 0xC: timer_window[index] = timer_window[index-1] +/- 0
• 0xD: timer_window[index] = timer_window[index-1] +/- 3
• 0xE: timer_window[index] = timer_window[index-1] +/- 10
• 0xF: timer_window[index] = timer_window[index-1] +/- 20

Caveat: Safe migration of existing settings will be challenging.

[Andreas-Marx]

I have implemented this feature for my own use. Presentation in the GUI leaves room for improvement :-)

Code can be found at https://github.com/Andreas-Marx/Tasmota.git Extend_Timer_Randomization_Window

tasmota/xdrv_09_timers.ino | 86 ++++++++++++++++++++++++++++------------------
1 file changed, 52 insertions(+), 34 deletions(-)