Dedicated Dash Tablet

[maccos01]

Hey Guys and Girls, I am looking for assistance for a project I am working on. I am not very skilled with digital devices or programming, so that is where I will need your experience.
My goal is to have my Nexus 7 permanently mounted in the dash of my car. This is a custom car and there is no radio.
My goal is to have the following:
Bluetooth OBD2 adapter to send engine data to tablet (this I already have figured out).
The dash will be used to display all of the engine data (currently using Torque App with RacingMeter Plugin (because I like the display layout)).
I would also like to use the dash as a backup camera as it is nearly impossible to see behind yourself once in the car.
Lastly I would like to have navigation available as well, not important at this time though.

I would like these systems to work without having to actually touch the Nexus 7 display (unless going into navigator mode, then its OK to use the screen). The basic function should be this:
Turn ignition on and the tablet turns on (awakens), shows a display screen and then the dash display appears and connects to the bluetooth.
At any time that the ignition is on and I put the car in reverse, the display will immediately show the video from the backup camera, and once it is taken out of reverse, it goes back to the last screen (either the dash or any other screen that I was previously in).
When I turn the ignition off, a display will show and then the tablet will sleep and go into a low power mode.

I found out that the Tasker App is going to be perfect for programming this and began to learn more about how it works. I found these series of videos to be pretty good at explaining what I need to do with Tasker to get me part of the way through.

So this is a two-part problem 1. Hardware & 2. Software (Tasker programming).

For the hardware, I uploaded a file to show my current plan of attack.
My current questions are:
1.Will the USB port give the tablet enough power to keep it going with full brightness, Bluetooth, GPS & Torque App all running at once? I noticed on the reviews of the USB charger (http://www.amazon.com/gp/product/B0082CXEI8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1) that it may need to be modified to get more charging capacity out of it. It appears that the tablet wants to see a certain level of power for it to trigger the Tasker state, and ofcourse I want it to be able to keep up with the usage of the tablet.
2. I read that a good USB cable will help for optimizing the charging rate, so I threw in the PortaPow USB cable. Since I am also planning on using an OTG cable, I hope that the OTG cable will not bottleneck the power supply to the tablet.
3. Connecting the backup camera to the tablet. I found a youtube video (

) which shows a backup camera connected to a tablet with what appears to be an EasyCap USB audio/video adapter. I am not sure if this is the right thing that I need or not to do the job? I bought this: http://www.amazon.com/gp/product/B0019SSSMY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
4. By sending power to the camera when the car is put in reverse, and a video signal sent to the tablet, I am hoping that will generate some signal that can be used to open an app to show the video. Am I on the right track here?

For the software:
I have been playing around with Tasker and this is what I have so far.
1. When power is plugged in, the tablet awakens, shows a custom display and then opens the Torque app and turns on Bluetooth. When I remove the power, the custom display shows again and the screen times-out shortly after, turning off bluetooth. This usually works, but sometimes it doesnt. You can see in my video what I mean. (I'll put a link to the video when its done uploading)
2. For low power-state when the car is going to sit for 7 days at a time, I am hoping that the tablet won't completely die if it doesnt have any power. I looked into going into airplane mode, but that is not supported on Tasker from what I can tell, unless I believe you really get deep into things, which I have no experience. Are there other ways to go about going into a low-power mode? What about if the tablet turns off after 10 hrs of inactivity, would it be possible to have it automatically power back on quickly once power is re-supplied after the tablet has been off? I was also thinking about using a wireless charger that can "trickle" charge the tablet to keep it charged for days at a time, while the USB power is off. Not sure if that will kill the car battery?
3. I only really need GPS if I use the tablet as a navigator (google maps). I was thinking that I could program a button that is transparent over the dash display such that if I did a long press on that button, it would open up google maps and turn GPS on. Maybe it would be preferable to easily switch back and forth between Maps and the dash display. I am not too concerned about it at this time though, that can be figured out later.

It would be great if there was someone available to help step me through the software programming. I am not the greatest at it.

Please let me know if you have suggestions, ways to do it better, or anything else. I should have the hardware mentioned above in the next week or so.

 

[codesplice]

Hi @maccos01, John B. here - welcome to Android Forums

I went ahead and moved your thread into our Tasker-specific subforum. While not all of the questions in your post are directly related to Tasker, this also happens to be where many of our nerds members most able to help out tend to hang. Some of the topics covered may best be addressed through their own threads in other parts of the site, but this is probably the best place to start.

Is the Nexus 7 rooted? Root access greatly enhances the abilities of apps like Tasker to be able to control apps, radios, etc. It's also pretty easy to accomplish on Nexus devices, but let us know if you need some help on that front. (We also have dedicated forums for the Nexus 7 (Nexus 7 (2012), Nexus 7 (2013)) - which version is yours?)

 

[maccos01]

Hi John,
Thanks for moving the thread, anything that helps get the right people, I am for it.

The Nexus is not rooted. If that is necessary to do this, I am up for it, if someone can just refer me to a how-to, then I can do that and anything else I should know about rooting. It is a Nexus 7 2013, 32 GB. I dont have a service carrier, I just bought it off ebay in December of 2014. If I look under the "About tablet" it says it is using Android version 5.0.2 with Kernel version 3.4.0.

Still working on uploading the tasker video which shows what I have at the moment....slow connection here.

 

[codesplice]

We've got a pretty solid "how to root" guide here: How to Manually Root the 2013 Nexus 7

I strongly recommend that you do go that route, which doesn't take any shortcuts and also gets you at least somewhat familiar with the fastboot bootloader and recovery options - which subsequently makes you better prepared if you do run into issues down the road.

If you'd rather just root and forget it, WugFresh's Nexus Root Toolkit is another option. It's safe and easy, or so I've heard.

Either route should work fine for your needs, and you'll then be able to use Tasker plugins like Secure Settings to toggle radios and terminate apps. I've used that for managing Airplane Mode on my Nexus 4 running 5.0.1, so it should work fine on your tablet as well.

When you have a moment, could you share some screenshots of your current Tasker configuration? That may help us to track down any inconsistencies.

 

[maccos01]

I looked into the rooting setup, I just have to get a moment to to that before I go too far.

Attached are some screenshots of the current config with Tasker. I only have one profile with an Exit Task Condtion. This is different than how the cbutters guy did it on his video in the original post. I tried both ways and both seem to give the same results. I am just playing around and trying to learn the app at this time, so if you think its better to take a different approach for what I am after, I am all ears.


Video is finally done, this shows what I am seeing with the current program:

 

[vosg]

You can simulate screen touches to launch the speedometer but your tablet needs root. Here's is a tutorial:

http://www.pocketables.com/2013/07/how-to-emulate-touch-input-using-tasker-and-root.html

I suppose getting root will also help killing the app when power is disconnected.

 

[codesplice]

Hey @maccos01,

Wanted to let you know that I spun the root-specific discussion out into its own dedicated thread: http://androidforums.com/threads/rooting-help-n7-2013.912263/

Hopefully that will let the rooting experts (who may not hang out in the Tasker forum) help out.

 

[maccos01]

OK, back to the good stuff now that the root is taken care of.

John, you mentioned having the tablet shut down and be able to start back up automatically when the device is powered. I assume if it starts up from being off, there is no simple way to get it to power up quickly (it currently takes about 40 seconds for the home page to appear when its turned on). (I wouldn't want it to take that long every time I start the car. Assuming that is the case, would it be possible to program a feature that says: if the USB power has not been enabled for 10? hours, and the battery % is below 30?, then power off device. This I think would be perfect for the longer lapses where the car will sit for 2 weeks, and when I go to start it up for the first time it will take a bit for the tablet to power up and load, but that is acceptable. The remaining on/off cycles during that day, the tablet would be constantly being used and wont power off and there wont be a start up delay.

 

[codesplice]

You shouldn't even need to set up anything for fully powering the device off if the battery gets low - it will actually do that on its own once the battery gets extremely low. (Just for gee-whiz information, I've had my N7 idle off-charge but with Wifi (and sync) still enabled for about 72 hours now; it's at 76%, estimating 9 more days before it shuts off. So if you get everything tweaked correctly (no radios, no sync while in standby) it shouldn't have any problems lasting a week or more.).

(Did I close all those parentheses?)

Have you seen the silly little charging-battery animation that shows up on the screen when the tablet is turned off (actually shut down) and you connect it to power? That's the special "charge mode" that just boots up enough of the system to operate the charging circuitry and show that animation on the screen. Executing fastboot oem-off-mode charge 0 disables that silly charge mode, which means that the powered-off device will automatically boot all the way into Android whenever external power is applied.

It definitely sounds like we're on the right track with that.

 

[maccos01]

Wow, that is a long time that the battery lasts without being powered. From the factory, the tablet was losing all power within 2-3 days of sitting on the desk, not being used.

So how do you go about enabling this "power up when plugged in" is this a tasker setting?

 

[codesplice]

Remember when you were rooting and had to type out "fastboot oem unlock"? It's just like that, just a slightly different magical incantation verbiage.

So basically, reboot the tablet to the bootloader, connect it to your computer, run fastboot devices from your mini-SDK tools directory to make sure it's connected correctly, and then execute fastboot oem-off-mode charge 0.

You can then unplug the tablet, power it off, and when you plug it back in it SHOULD boot up. *fingers crossed*

I'm about to have to call it a night though, so good luck - I'll find out how it went in the morning.

 

[maccos01]

hmm, doesnt seem to be working. I am now showing the device is connected in the command prompt as you can see in the screenshot. I am in bootloader mode and I typed your command and the long script appears in the command prompt as you can see. I unplug, then power off and then plug the usb back in and the battery logo appears for a second, but tablet does not turn on.

is it "...charge o" (as in the letter "O") or is that the number zero? I tried both and I get the same result.

 

[codesplice]

hmm, doesnt seem to be working. I am now showing the device is connected in the command prompt as you can see in the screenshot. I am in bootloader mode and I typed your command and the long script appears in the command prompt as you can see. I unplug, then power off and then plug the usb back in and the battery logo appears for a second, but tablet does not turn on.

is it "...charge o" (as in the letter "O") or is that the number zero? I tried both and I get the same result.

Sorry, I was recalling the command incorrectly.

I just tried it on my 2013 N7, though, and got it working:

fastboot oem off-mode-charge 0

(I had the right words, just wrong hyphenation. Computers are apparently picky about that sort of thing.)

Using the right commands should work - sorry about that!

 

[maccos01]

That works! Thanks!

Today I received all the hardware in my diagram in the original post. Backup Camera, EasyCap adapter, OTG cable, etc. Seems that I am not getting any video signal to the tablet. I did some research and apparently there are various types of EasyCap connectors. After looking at mine, it is actually named "EasierCap", what the heck! Doesn't match the images in the Amazon product page, turns out there are sub-prime units floating around. I saw on another forum that the "correct" EasyCAP adapter has to have a STK1160 chip. I am going to try ordering another from a different supplier, fingers crossed. I didn't see any alternatives to this product, at least that people are using for this application.

The OTG cable has a poor physical connection to the tablet, it easily falls out. Dang...need to find a new one of those. Anyone have advice for a good supply? I didn't think it would be that hard to get quality hardware.

Anyway, I have a specific tasker question. As you saw in my video earler, the show-scene image would take up the entire screen, like I wanted. I know originally it took me some time to get it that way. I for some reason cannot get it to show up like that anymore....what am I doing wrong? I am using the same image (same size).

 

[maccos01]

I also noticed that the OTB cable does not charge the device. Is that because it is not the correct cable, or does something with my software need to be changed to allow charging? Sorry, not a tasker question.

 

[codesplice]

Unfortunately I don't have a lot of experiences with Scenes in Tasker so someone else may need to step up to help with that piece.

I also haven't done a whole lot of playing with OTG - my daily driver N4 doesn't support it, so I just haven't experimented very much.

What sort of cable do you have? Is it a straight or a Y-cable with a separate power input?

Edit: Again, no personal experience here, but it sounds like you might need a custom kernel to enable the tablet to charge while OTG'ing: http://mehrvarz.github.io/usb-host-mode-power-management-nexus7/ That may be a good question to throw up back in the N7 2013 All-Things-Root subforum to see if anyone does have some practical experience to share .

 

[maccos01]

I attached a reference pic of the OTG cable, not my exact one. Thy one I have just doesn't clip into the tablet well enough. You have to apply pressure on it for it to connect, no good.

I made some progress on the backup camera. From the play store, I installed an app called EasyCap Viewer. I had to change some of the settings in the app, but now I am getting video on the tablet from the backup cam and the app opens/closes automatically when the power to the camera is toggled (just like my schematic shows in the original post). I attached a picture of the test setup. Turns out the "knockoff" EasierCap actually does work after-all.

Edit: Again, no personal experience here, but it sounds like you might need a custom kernel to enable the tablet to charge while OTG'ing: http://mehrvarz.github.io/usb-host-mode-power-management-nexus7/ That may be a good question to throw up back in the N7 2013 All-Things-Root subforum to see if anyone does have some practical experience to share .

Yes your are right I did come to that same conclusion...need a custom kernel. I have emailed that guy "Timur" to see if I can get my hands on it. Sounds like that is exactly what I need.

 

[miggzz]

did you ever get it to connect to the car?