Adjust Clock

Adjusts clock continually in the background to counter clock drift.

Basic usage

First you need to determine the clock drift of your watch in PPM (parts per million).

For example if you measure that your watch clock is too fast by 5 seconds in 24 hours, then PPM is 5 / (24*60*60) * 1000000 = 57.9.

Then set fixed PPM in settings to that value and this widget will continually adjust the clock by that amount.

Make sure that Mode is set to Basic. (Configuring Advanced mode is not documented.)

Settings

See Basic logic below for more details.

• PPM x 10 - change fixed PPM in steps of 10
• PPM x 1 - change fixed PPM in steps of 1
• PPM x 0.1 - change fixed PPM in steps of 0.1
• Update Interval - How often to update widget and clock error.
• Threshold - Threshold for adjusting clock. When clock error exceeds this threshold, clock is adjusted with setTime.
• Save State - If On clock error state is saved to file when widget exits, if needed. That is recommended and default setting. If Off clock error state is forgotten and reset to 0 whenever widget is restarted, for example when going to Launcher. This can cause significant inaccuracy especially with large Update Interval or Threshold.
• Debug Log - Where to log debug messages.
  • Off: No debug logging.
  • Console: Log to console.
  • File: Log to file widadjust.log. This file is not deleted if widget is removed.
  • Both: Log to console and file.
• Mode
  • Disabled: Widget is disabled and doesn't adjust clock.
  • Basic: Use fixed PPM configured in main menu.
  • Advanced: Use temperature-dependent PPM configured in submenu.
• Advanced PPM - Configure values A, B and C for temperature-dependent PPM which is calculated as At^2 + Bt + C where t is temperature in Celsius.

Display

Widget shows clock error in milliseconds and PPM.

Basic logic

• When widget starts, clock error state is loaded from file widadjust.state.
• While widget is running, widget display and clock error is updated periodically (Update Interval) according to PPM.
• When clock error exceeds Threshold clock is adjusted with setTime.
• When widget exists, clock error state is saved to file widadjust.state if needed.

Services

now

WIDGETS.adjust.now() returns adjusted Date.now().

To support also case where this widget isn't present, the following code can be used:

function adjustedNow() {
  return WIDGETS.adjust ? WIDGETS.adjust.now() : Date.now();
}

setClockError

WIDGETS.adjust.setClockError(x) sets clock error to given value, in milliseconds and returns the old clock error or undefined if widget is disabled.

GitHub

Main repository for this widget is malaire/banglejs.

Please report any issues or feature requests there.

Acknowledgment

Uses Clock Settings icon by Icons8.