================================================================== HTC Desire 200 - auto boot when charger is plugged in

What's this?

I have made a car alarm system for android - tATA Protector. I have an android phone in my car hidden somewhere, I use it for GPS tracker, location based car alarm system, "engine start" detection, etc. The phone is connected to a charger, when the car's engine is running the phone is being charged.

If I don't use my car for a while the phone will discharge and power off. So I needed a solution to automatically power on my phone when it's being charged.

Further info, apps:

• https://play.google.com/store/apps/details?id=com.tomicooler.tata.protector
• https://play.google.com/store/apps/details?id=com.tomicooler.tata.watchergcm
• https://play.google.com/store/apps/details?id=com.tomicooler.tata.watchersms

Rooting

Open your bootloader: http://www.htcdev.com/bootloader/

Root your phone: http://forum.xda-developers.com/showthread.php?t=1886460

(3) New Standard-Root (thx Ariel Berkman)

Auto boot

I got it working - auto boot when charger is plugged in - on my HTC Desire 200. There is no playlpm/lpm/idot/chargemon on these HTC devices. Fortunately there is something similar, /system/bin/zchgd. This is a service that takes care for the charging animation. On this specific device, the charging animation is played even though the phone is powered on (on the lockscreen), it is also played when the phone is powered off and it's on a charger. (BTW: the images for the animation can be found at /system/media/zchrgd.)

As I found out, the zchgd service is started differently when the phone is powered off or on. I just grep through the init scripts, in my case /init.gtou.rc:

service zchgd_offmode /system/bin/zchgd -pseudooffmode
    user root
    group root graphics
    disabled

service zchgd_onmode /system/bin/zchgd -onmode
    user root
    group root graphics

on property:dev.zcharge=true
    start zchgd_onmode

on property:dev.zcharge=false
    stop zchgd_onmode

So, I created a fake zchgd service, a simple sh script that replaces the original service.

Steps:

adb shell
su
mount -o rw,remount,rw /system
cd /system/bin
ls -l zchgd*
mv zchgd zchgd_original
touch zchgd
vi zchgd # <- insert content, see zchgd service
chmod 0755 zchgd
chown root.shell zchgd
ls -l zchgd*

When the service is stared with -pseudooffmode argument, then it checks the battery status periodically (every minute in my case). If the phone is being charged or the battery is full then it will automatically restart the phone. I could not use /system/bin/reboot, I got permission errors, even though I had them, I'm pretty sure about that :). So I restart it with a hack, that two echo lines. The -onmode is there only because, I don't want to see the charging animation even if my phone is powered on.

You can debug the script with adb logcat -s zchgdwrapper. I hope this was helpful!

IMPORTANT

For this to work, you MUST enable Settings/Power/Fast boot option. It won't work if it is disabled, I think without fast boot another firmware is booted, but not sure about that.

Also I have this config in SuperSU#, I don't think it is necessary but, here it is:

• Default Acces < Grant
• Enable su during boot
• Trust system user