I cannot get some Android devices to wake up using the AlarmManager. Following the advice in other StackOverflow posts, I am testing CommonsWares cwac-wakeful demo unmodified, compiled in Eclipse, and sent directly to my tablet devices.
When the screen is on the app wakes every 15 minutes and dutifully writes a log message, if I switch the screen off (short press on the power button) and remove the USB cable, then reconnect say 30 minutes later, there are no log messages for the period during which the device was asleep. The alarm does trigger immediately after I wake the device up (according to the log message timestamp). If I leave the USB cable connected the alarm does trigger even with the screen off, presumably because the device is in “debug” mode.
I have seen this behaviour on an older Android 2.2 tablet and I think it might be a bug in the hardware or OS common to both devices. However, I would like to rule out a bug in the cwac-wakeful utility and “operator error” if possible.
Has anyone else seen this behaviour and have any suggestions about further diagnostics or remedies?
I actually get the same behaviour when I set the built-in clock alarm from the home page, i.e. the A90 and the VEGAn-TAB don’t wake up until the next manual power on. Therefore it must be a fundamental problem with the tablets rather than a bug in AlarmManager or WakefulIntentService.