WM6.5 Lock screen turns off GPS service

Question

I'm developing a GPS tracker For WM6.5 which can receive coordinates with GPS and send it into. All works fine but I have one problem when the screen is locked: packets are sending but GPS does not work (it shows same position) but when I wake up my phone then the GPS starts working again.

How can I can I keep the GPS service running when the screen is locked? I'm testing with a HTC Touch 2 and my solution is written in C#. For GPS i'm using the Microsoft.WindowsMobile.Samples.Location library.

Answer 1

This is probably because the device is going to sleep. If it stays awake, the battery will run down quickly. Mobile devices are designed to enter a hibernate like state almost immediately so that they last longer on a charge.

If battery life is of no concern, you could go into the power settings and tell it to never turn off. However, you risk having a dead device if your battery ever runs out.

Answer 2

Windows Mobile devices know different power states.See HKEY_LOCAL_MACHINE\\System\\CurrentControlSet\\Control\\Power...

An application can request a specific minimum power state using SetPowerRequirement API call: http://msdn.microsoft.com/en-us/library/ms920689.aspx . Instead of specifying which device should not fall below a power reqirement, you can also specify a general requirement for the application: http://www.hjgode.de/wp/2009/07/14/howto-run-an-application-periodically/#more-193 using SetPowerRequirement and SetSystemPowerState.

I recommend using SetSystemPowerState, if you want to avoid the device falls into a hibernate mode. If you know the GPS port and GUID, you can also use SetPowerRequirement with the device name.

I have no experience with changing the Control\\Power branches to change the behaviour of a device within a named power state.

You may try SetSystemPowerState with Power_State_Unattended or enable the user to choose for 'keep device ON'.