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Caffeine

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Caffeine

If you have problems with your PC locking or going to sleep, caffeine will keep it awake. It works by simulating a keypress once every 59 seconds, so your machine thinks you're still working at the keyboard, so won't lock the screen or activate the screensaver.

The icon is shown above - it's the leftmost one in the task tray, and this is all you see. Double-clicking the icon empties the coffee pot (that's what the icon is) and temporarily disables the program. Double-clicking it again refills the pot, and will keep your machine awake.

By default the app starts enabled, and works every 59 seconds. There are some command line switches you can use to alter this behaviour:

  • xx - where xx is a number which sets the number of seconds between simulated keypresses. This must be the first text on the commandline
  • -startoff - application starts disabled.
  • -exitafter:xx - application will terminate after xx minutes
  • -activefor:xx - application will become inactive after xx minutes
  • -inactivefor:xx - application will become active after xx minutes
  • -appexit - terminates current running instance of application
  • -appon - makes the current running instance of the application active
  • -appoff - makes the current running instance of the application inactive
  • -apptoggle - toggles the running state of the current running instance of the application
  • -apptoggleshowdlg - toggles the running state, and shows dialog
  • -replace - closes the current running instance, replacing it
  • -noicon - does not show a task tray icon
  • -useshift - simulate the shift key instead of F15
  • -showdlg - shows a dialog indicating whether caffeine is active
  • -ontaskbar - show a task bar button (use with -showdlg)
  • -allowss - prevent sleep, but allow the screensaver to start
  • -key:xx - simulate using virtual key code xx
      Note: the codes on the linked page are in Hex, convert them to decimal for use with this parameter
  • -keypress - simulate a full key press, not just a key up event

Windows 98: Caffeine works by simulating the F15 key down and up events every 59 seconds.
Windows 2000/XP/Vista/7/8: Caffeine works by simulating an F15 key up event every 59 seconds.

Of all the key presses available, F15 is probably the least intrusive (I've never seen a PC keyboard with that key!), and least likely to interfere with your work.

Video

Caffeine user humancar2n has put together a short YouTube video showing how the app works.

Mac version

Do you need this functionality on your Mac? Lighthead Software have written a separate app, also named Caffeine, which can help you out.

Versions

v1.6 - 8th July 13
New command line options:

  • -allowss
  • -ontaskbar
  • -apptoggleshowdlg
  • -key:xx
  • -keypress
Added menu items to go Active/Inactive
Type in About box corrected
-apptoggle will re-show the dialog if it was originally shown

v1.5 - 2nd November 10
New command line options:

  • -inactivefor
  • -showdlg
  • -apptoggle
Simulated keypress changed from right context menu key to F15 as this is likely to be even less intrusive.

v1.4 - 18th July 09
New command line options:

  • -replace
  • -noicon
  • -useshift
Hovering over the tray icon now shows the status of the app

v1.35 - 28th May 09
Simulated keypress changed from shift to the right context menu key (at the suggestion of Kevin Kleinfelter) as this is likely to be less intrusive.

v1.3 - 3rd February 09
Command line switches added to terminate the app after x minutes, disable the app after x minutes, and enable or disable the currently running instance of the app

v1.2 - 15th March 08
Command line switches added to set the interval and to start disabled

caffeine.zip (14k)

© Zhorn Software 2013