Touch screen suddenly inaccurate; goes crazy

[CappinMorgan]

Hello, i am using a Motorola Droid and I ran into the same thing and it was because I was using a 3rd party charger. I am getting the specs, but when I used my wifes Blackberry cord it worked fine. When I use the USB cable and the wall plug it works fine.

I firmly believe it is the amount of power being delivered, I am getting the specs between the two and will post.

One theory on the USB cable doing this is that USB ports provide different power depending on what you are plugging it into. On most PC's the USB ports on the back of the PC are fully powered, USB ports on the front, on USB hubs, on Monitors or Keyboards provide less power to the USB device plugged in.

Hope this helps.

[CappinMorgan]

Hello, I found that if your screen is acting wierd while charging, as described in the original post, that the power from the charger to the phone may be too low. My testings are below...

I purchased a 3rd party charger to have at work and the mA (milliamps) output was 350mA. It would make my Droids screen go crazy. I used my wifes Blackberry adapter which is 700mA and it worked great. The adapter out of the box is 850mA.

As for using your USB cord on your PC, USB ports like the ports on the back of your PC versus the ports on a USB hub, keyboard, monitor or even laptop will put out different voltages and mA's. Normally the ports on the back of a PC or USB hub that has its own power supply will be ok but this isn't something I have tested.

[ChrisK15]

Yeah, I guess that does make sense. Plugged into my laptop it jitters all over the place, but with the AC adapter, not so much. USB only puts out 5V at 500mA.

[Nobodyspecial]

just got the same issue i do have a non oem charger plugged into it right now and several apps but it doesnt seem to be the apps i have killed them all.

[delaen]

Only one app can run at one time.. the Android platform allows multiple apps to run at once.. BUT they aren't running, they are suspended while the front app that a user is using is running. All apps go thru various states.. if you are running a game, hit the HOME key and run another app, the game *might* still be running but Android sent it a message saying "Yo.. going to run a different app right now, you are going to be pasued for a bit.. save anything you want incase I have to shut you down later, and I'll resume you when this user switches back to you". Essentially, services can run in the background, and one foreground app can run. The rest of the apps are suspended until the user switches back to them. For apps that have a user interface AND seem to get notifications, as far as I know those are background services running. I am still very new to Android development tho, I am not sure if when you switch from one foreground app to the next, if the other apps that are suspended can still receive notifications or not. I think only the foreground app can receive notifications of any sort and other apps (that are not services) are suspended until the user switches back to one of them. I believe that is correct.. if another android developer knows for sure, please correct me if I am wrong.

You're really describing how almost any operating system handles running applications. You can make the distinction between "service" and GUI like they're not both part of the application, but I'm not sure it's the most accurate way to think about it.

A service+the GUI = the app. Android might not be drawing the screen of the application when it's in the background (why would it? no OS does), but if the service portion is still running and doing stuff, the application isn't paused or suspended - the GUI just isn't being rendered. At least from a user's perspective.

If I start my music and then switch to a GPS logging application, the music keeps playing. If I switch back to the music app, the GPS keeps logging. Both apps are running at the same time. Android does some fancy memory maintenance to try to optimize how much CPU/power these background apps use, but for all intents and purposes, both apps are running simultaneously and they'll both keep running in the background if you open a third app.

You're not wrong with what you're saying, but you're looking at it from a developer's perspective. To most people and for a majority of apps the background service IS the app and they DO keep consuming resources in the background.

So really it all depends on the app.

[delaen]

I bought a third party charger and experience the same touch screen inaccuracies when it's plugged in. When I remove it from the charger it immediately begins working properly again.

[Dream]

I have a similar issue but I dont think it has anything to do with the charger. Ill touch the screen to select something and it will scroll all the way up or down super fast. I just figured it was some kind of OS bug.

[tsitalon1]

I notice that the screen calibration for the droid is not nearly as good as my Itouch....I have to always touch just slightly above what I want.

Is there no calibration sequence at all?

[cal2vin]

When I have my droid plugged into my laptops USB port with the laptop being plugged into the wall charger my screen goes nuts. But when I unplug my computer charger and let it run on the battery the droids screen works fine. Could it be possibly getting too much power from the USB port when the computer is plugged into the wall?

[Dr. Tenma]

One issue I have had like this in the past with my Droid and laptop was due to the AC adapter not being properly grounded- usually a car inverter or such. Perhaps this is related? My Voyager would lock and unlock itself constantly when not grounded.