using a tablet in a car.. flow help request please

[bmccann101]

Hello all.. im brand new here... and while i am generally quite a smart guy.. this apps programming is a bit past my expertise.. Im no code writer and i did poorly in Visio too lol.
The item is a Nexus 7 tablet, gen 2. Android.

I am looking for a way to use the tablet as permenatly mounted in the console of the car.. used for a program called DashCommander.. its a display of OBD2 functiosn as gauges etc..

WHat i am looking for is a way to wake the tablet up when it senses an AC adapter connected w power ( car turns on) and to power down when AC plug is off... if this is impossible i may have a solution by remote mounting the power button from the tablet circuit board.


-Id like the tablet to turn on.. set the display timer to never... to open bluetooth and connect to the OBD2 adapter in the car.. and to start the DashCommand program..

-Id also like the tablet to power off when the AC adapter charging state is turned OFF.

This will get me moving for now.. I bought the items and programs while following a thread done by soneone who ahs done just this.. but i am unable to reach that member on that forum.

Thank you a TON!

Its going in this car btw, my render.. the car is nearly complete now..




.. here are some picture examples..

[kamil_w]

There is no way to turn on/off device. All you can do is only turn off display (standby mode) and wake up device, so if your car will not be used over few days you will have no possibility to turn it on if you hide phisical button.

[MURTUMA]

It is possible to turn device off using execute root command action. Sorry, I cant remember that right now, but the command is easily found with google or maybe on the forums. Also, you might want to check Secure settings plugin on play store. It works great with AM and allows you to shut down your device among other things.

Obviously it is impossible to turn device on by software. I should not need to tell you the reasons?

[bmccann101]

yes i can imagine having it turn on was a stretch, but im not fully aware of phone/tablet softwre capability honestly.

I will therefore remove the back case and have some leads soldered to the PCB.. i can easily then use a timer relay to momentarily send turn on power when the car is turned on.
Using the ap would be far easier if it was available.

[Wibbly]

A bit off topic, but you may want to consider leaving it in standby/screen off rather than switching it off, as the standby current should be very low once it goes to sleep. It should be in the same order of magnitude as a car alarm or similar. So you will need a a capability to reset it if it crashes/turn it fully off if you need to (still wire to the on-off button) but I wouldn't be too concerned you'd have to use that a lot. Even if you COULD do this in software, you still need a away to recover/reset from a nasty crash (of the tablet, let alone the car!) anyway.

Why not try and measure the current to prove this? Every one milliamp of standby current taken by the tablet where it connects to your car wiring will discharge your car battery by 24mAh a day. Your car battery's capacity is going to be 30Ah min and possibly more than twice that! So at, say, 20mA standby current a 30Ah (that's 30,000mA/h!) battery would go completely flat in more than 60 days if you never started the car. Of course there will be other drains on the car battery (such as that car alarm) and you need some capacity left to be able to start the car...

I don't know if this would work with your N7, but maybe this would help if you want to take it to the max http://mehrvarz.github.io/nexus-7-usbrom/ ?