TaoK wrote: > - If not, are "ACTION_BATTERY_CHANGED" intents the best way to > monitor for battery drain?
There is also a separate ACTION_BATTERY_LOW Intent, but it is undocumented how low LOW is. > - Does Android really put the CPU to sleep when you lock the phone? Not necessarily immediately, but yes, the CPU will go to sleep. > - Otherwise, how does it decide when to put the CPU to sleep? When nothing holds a WakeLock (or a native equivalent), I imagine. > - How does this CPU sleep affect "naive" simple services? A sleeping CPU processes no instructions, so those services stop in their tracks until the CPU starts up again. > - How does this CPU sleep affect broadcasted intents such as > "ACTION_BATTERY_CHANGED" and "ACTION_TIME_TICK"? I seriously hope ACTION_TIME_TICK is not sent when the CPU is off. I have no idea about the former. > - Can a service "schedule" itself to cause no battery drain for, say, > 30 minutes, wake up and do something for a second, and sleep for 30 > minutes again (and does this effectively equal zero drain on the > battery?) You found part of the answer for this in your followup post. AlarmManager lets you schedule service work. However, bear in mind that "something" may take more than a second if it depends on a radio. Jeff Sharkey's "Coding for Life -- Battery Life, That Is" Google I/O presentation on power drain was first-rate: http://wiki.andmob.org/videos > I recently aquired a Samsung Galaxy i7500 (from Germany, via a mailbox/ > shipping company) They shipped you a mailbox? ;-) > Several times, the phone has run out of batteries and turned off, but > until today I didn't have proof - there is NO AUDIBLE WARNING that the > phone is running out of battery - how is this possible?? I don't recall audible warnings for low battery on my G1, if that helps. > Assuming that this is simply a flaw in the OS (on the Galaxy I'm > running Cupcake/1.5 standard with Google APIs, haven't tried rooting > it yet), I guess the only solution would be to write a service that > somehow monitors the battery level and does something when it start > running low. The old Power Manager app used to do that, but I think it may have been lobotomized with the Android 1.5 secure settings changes. On the other hand, somebody linked to this app today, and it looks really interesting: http://www.gearsoft.mobi/wisyncplus.html > In an (unrelated, location-based) application I'm writing now I use > the "ACTION_BATTERY_CHANGED" Intent Action with a BroadcastListener to > find out if the battery is running low (and quit doing expensive GPS > stuff if that is the case), and that is, or at least seems to be, a > very easy solution... *applause* > If I'm understanding correctly, even if I ran a service that I didn't > quit, it would somehow be put to sleep (until the user did something > to wake up the CPU) unless I did something clever with CPU Wake locks? Correct. Keeping a service running has more of an impact in terms of memory consumption than battery consumption, assuming the service is not being stupid while it's running (e.g., busy-wait in a tight loop). > Is the "correct" approach a combination of the two? > > - Service Yes. > - running all the time Use AlarmManager if possible. > - When the phone is awake / active: > - checks battery status (or listens for "ACTION_BATTERY_CHANGED" > intents for a couple minutes) every 5 minutes. > - when the phone is asleep: voluntarily puts itself to sleep for 30 > minutes at a time, listens for "ACTION_BATTERY_CHANGED" intents for a > few minutes, and goes to sleep again. If you're not using a radio, and not doing much work per alarm cycle, I wouldn't bother with the ACTION_BATTERY_CHANGED stuff, as you won't be a major contributor to battery drain. However, the general notion of scaling things back on low battery is a good implementation idea -- in fact, I have a tutorial in _Android Programming Tutorials_ just to make that point. -- Mark Murphy (a Commons Guy) http://commonsware.com | http://twitter.com/commonsguy Android App Developer Training: http://commonsware.com/training.html --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
