April 16, 2014

Samsung GT-I5500 with Android 2.1-update1: AlarmManager not suitable

Nov 13th, 2010 | By fabian | Category: Blog

Recently, there was a Samsung GT-I5500 (Android 2.1-update1) user with a problem similar to that described in one of my recent posts (→LINK). So I sent him the test application I already used to figure out the AlarmManager problem on Samsung’s Galaxy S with Android 2.1-update. Here is the result:

If everything went OK, the whole red line should be covered by blue dots. But the result seems to be very odd, because there are many alarm events just missing, as you can see in this plot. So it’s not only that the CPU was not waked up correctly, it’s even that these alarm events are completely removed.
The second point: The user turned on the screen three times. At (roughly) half past two, at half past eight and finally at 10 o’clock. At these times, the last scheduled alarm, which was not fired up yet, was processed. Because the CPU stayed on for a short while at these times, multiple events went off (in the intended sequential way). Here, it is important to mention that the first event (respectively) of these sequences was delayed by an arbitrary amount of time (one minute at the maximum, of course).The following events had no time delay.

So my guess: Samsung avoids waking up the CPU from standby mode in general. The alarm events are not fired up until the user turns on the screen. This may save battery power in an efficient way, but it makes it impossible to schedule time-dependend tasks (like AlarmDroid does). This avoids abuse by unpractised application developers, but also rattens serious applicatoins.
And secondly: when scheduling repeating events, all events except the most recent are removed. In the background of the assumption above, this actually makes sense because it avoids repeating the same task multiple times once the screen turns on. But it’s unreasonable with application development.

Workaround

I don’t think there is a workaround for these device/firmware combination. (I don’t know how former firmware versions behave.)

My recommendation

I’m sorry for all of you who buyed this phone. But my recommendation is to either buy another phone or to install an alternative firmware. The way it works now, you won’t enjoy Android very much because the AlarmManager is one of the most important tools in Android and it is used in many applications.

12 Comments to “Samsung GT-I5500 with Android 2.1-update1: AlarmManager not suitable”

  1. fabian says:

    By the way, I guess the Samsung i9000 Galaxy S with Android 2.1 (not 2.1-update!) behaves in the same way.

  2. Paul says:

    This is so stupid. Because of the alarm clock not working I’ve arrived late at work. I figure that it has something to do with the sleep mode of the CPU.. because the alarm worked when I’ve tested it to fire 1 hour in advance. I hope i will find out something to fix this.. otherwise the alarm is useless.

  3. fabian says:

    I guess it’s just Samsung’s way to save battery power and to prevent application programmers to wake up the CPU too frequently. On the one hand it works: battery power is indeed saved. But on the other hand, any application that uses Android’s AlarmManager will fail.

    An interesting question aside: Does the default alarm clock of your GT-I5500 work as it should?

  4. Paul says:

    Yes it works. I’ve tested some other Android alarms like Alarm plus v2 and Android Alarm but because they did not work i’ve uninstalled them and switch back to the default, even if it lacks some key features like setting up a specific audio file to wake you up.

    Also I’ve searched other forums and found out that it’s not only Samsung phones that are having this issue, there are other people who have HTC or LG with the same problem. So I think this is related to the OS Android 2.1.

    I’ve manage to do some tests with the default alarm and as a result after 3 hours of inactivity, the alarm still worked. I’ve read that after 6 hours the system enters the so called “sleep mode”. I hope i will mange to test it tonight for 6 hours.

  5. Paul says:

    Back again, done 2 tests.

    First I’ve set up the alarm 5 hours and 40 min in advance, then I’ve set it to 6 hours in advance. Both ran successfully. I will test for 6 hours and 55 min, then for 7 hours, in order to see the moment the phone enters the “deep sleep” (if it exists or not).

    • laura says:

      Yeah, mine doesn’t work at all, not the default alarm or anything i download. It’s just so frustrating :( Any ideas?

  6. fabian says:

    Good news! The issue seems to be fixed on devices with Android 2.2. So if you can get the upgrade, do it :)

  7. dwyane says:

    hi, i having problems with the battery on the samsung galaxy 5 (gt-i5500) i charge it over night and it lasts about an hour, i got a new battery thinking that the old battery was the problem, but this does not seem to be the case, i have noticed that the gold plate on the charging block prongs have turned silver, will this make any difference to the battery holding charge, any help would be much appreciated, thanks :)

  8. liz swanage says:

    Hi my son gave me a samsung gt 15500 for xmas but the battery life is really dissapointing he turned off any running apps but still only lasts about 11hrs!!! I do have 2 alarm times set to go every day (and they do go off as set every time!) is it this that is causing rubbish battery staying power.I don’t even use the phone somedays and it still only lasts a short day!!! any help would be great…thanks

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