Tablet PC as Carputer?

[solidxsnake]

For power-on/power-off delays and timing, you'll want something like this: http://www.ebay.com/itm/5V-Power-OFF-Delay-Relay-Module-Delay-Circuit-Module-/121125210233

 

I'd probably approach this as follows: I'd leave my 12V-5V converter hooked up to a constant +12V source (the current draw is negligible when idle, on the order of uA). I'd use a time-delay relay between the converter and the input to the USB-OTG Y cable. It will switch on instantly, and delay switch-off by some time (probably 10-30 seconds). Then I'd toss a second, regular relay in between the micro-USB end of the Y cable (between the tablet and the power source, but NOT between the peripherals and the power source). Both of these relays would be switched with +12V switched power from the car.

 

Once the key is turned, everything gets power "instantaneously." This would trigger the tablet to do its power-on sequence (wake screen, enable radios, mount external storage, etc.) and power all the peripherals. On short power losses (i.e. cranking), power will remain to the peripherals, but not the tablet... this is easily handled by having a delayed shut-down sequence on the tablet (via Tasker, etc.). On full power-off, the tablet will perform its shut-down sequence (unmount storage, kill apps, disable radios, etc.), then shut down. Then after the pre-programmed delay, the delayed relay will switch off, killing power to the peripherals.

[xt2005bonbon]

For power-on/power-off delays and timing, you'll want something like this: http://www.ebay.com/itm/5V-Power-OFF-Delay-Relay-Module-Delay-Circuit-Module-/121125210233

 

I'd probably approach this as follows: I'd leave my 12V-5V converter hooked up to a constant +12V source (the current draw is negligible when idle, on the order of uA). I'd use a time-delay relay between the converter and the input to the USB-OTG Y cable. It will switch on instantly, and delay switch-off by some time (probably 10-30 seconds). Then I'd toss a second, regular relay in between the micro-USB end of the Y cable (between the tablet and the power source, but NOT between the peripherals and the power source). Both of these relays would be switched with +12V switched power from the car.

 

Once the key is turned, everything gets power "instantaneously." This would trigger the tablet to do its power-on sequence (wake screen, enable radios, mount external storage, etc.) and power all the peripherals. On short power losses (i.e. cranking), power will remain to the peripherals, but not the tablet... this is easily handled by having a delayed shut-down sequence on the tablet (via Tasker, etc.). On full power-off, the tablet will perform its shut-down sequence (unmount storage, kill apps, disable radios, etc.), then shut down. Then after the pre-programmed delay, the delayed relay will switch off, killing power to the peripherals.

 

Can you provide a diagram ?

 

Also, do you know how to delay Timur's 5 second time out? I can't find how to do this anywhere. Currently, as soon as the tablet stops charging, it straightaway triggers Timur's time out. I'd like the time out to get triggered, say 10 sec AFTER it has sensed power is lost.

[solidxsnake]

Can you provide a diagram ?

 

Also, do you know how to delay Timur's 5 second time out? I can't find how to do this anywhere. Currently, as soon as the tablet stops charging, it straightaway triggers Timur's time out. I'd like the time out to get triggered, say 10 sec AFTER it has sensed power is lost.

 

I don't think it's possible to do that on the 2012 Timur's ROM (I refuse to give him a cent for the 2013 ROM), at least not through any graphical interface. Maybe there's a config file buried somewhere in the system partition, but I gave up on Timur's ROM and switched to AutoDroid pretty quickly since I think it's vastly superior in terms of interface. The kernel seemed a little less stable, but I generally had little problem until there were power fluctuations (from cranking, etc).

 

Here's a quick schematic detailing what I'm talking about. You'll have to custom-splice into your Y cable, but it's pretty straightforward. On power loss, the tablet will lose its 5V as soon as the relay can switch off (considered practically instantaneous). Set up a task/script to wait however long you would like (I'd say 3-5sec is a reasonable wait time for cranking power loss) on the tablet. Then set the time-delay relay to delay for some duration longer than that (I'd probably set it to 10-30 seconds or so... the extra power draw isn't really going to hurt anything). It might even be smart to get a power-on delay relay for the tablet, that way you can be sure your peripherals are powered before the tablet begins its wake-up sequence (I'd probably delay this by only a second or so... power-on times should be in the micro- to millisecond range for the peripherals).

 

This looks promising... a bit more expensive than I'd like but the form factor is really nice and compact: [ame=http://www.amazon.com/Timer-Delay-Relay-Hours-Cycling/dp/B00PD65UGA]Mini Timer Time Delay Relay .2 Sec to 1000 Hours. 12V 5A. Power on or Off Delay, Cycling and More - - Amazon.com[/ame]

 

This is probably what I'll end up getting: [ame=http://www.amazon.com/Delay-Relay-Switch-Module-Timer/dp/B00VFUG3KK/ref=sr_1_3?ie=UTF8&qid=1454108970&sr=8-3&keywords=time+delay+relay]Amazon.com: GERI® DC 12V Delay Relay Delay Turn On / Turn Off Switch Module with Timer: Home Improvement[/ame]

Edited January 29, 2016 by solidxsnake

[xt2005bonbon]

Thanks for the diagram. So I guess in my case, if I can't get to adjust Timur's time out, I should hook up the tablet to the time-delayed relay as well. Cause if I don't, it would still result in a mess when cranking: the Timur time out scenario gets triggered while cranking, and therefore dismounts all usb devices during that short period of time.

[solidxsnake]

Thanks for the diagram. So I guess in my case, if I can't get to adjust Timur's time out, I should hook up the tablet to the time-delayed relay as well. Cause if I don't, it would still result in a mess when cranking: the Timur time out scenario gets triggered while cranking, and therefore dismounts all usb devices during that short period of time.

 

Yeah. Honestly, I would just skip the Fixed-Installation mode and just use Tasker to handle your power-on/off sequencing. You'll still have OTG+Charging as well as fast-charge if you need it. Just make sure you kill any apps that could wakelock the tablet, and then flip on airplane mode and lock the screen. On wake, just turn the radios back on and unlock the screen. I don't think Timur's shutdown sequence does much else.

[Shogun506]

Yeah. Honestly, I would just skip the Fixed-Installation mode and just use Tasker to handle your power-on/off sequencing. You'll still have OTG+Charging as well as fast-charge if you need it. Just make sure you kill any apps that could wakelock the tablet, and then flip on airplane mode and lock the screen. On wake, just turn the radios back on and unlock the screen. I don't think Timur's shutdown sequence does much else.

 

"Deep sleep battery saver" is an app that will do the same thing as Timur's sleep but without any power issues. It activates any time the screen turns off so just make Tasker turn the screen off when power is disconnected and voila

[xt2005bonbon]

Thanks guys for your inputs. Appreciate it.

[solidxsnake]

"Deep sleep battery saver" is an app that will do the same thing as Timur's sleep but without any power issues. It activates any time the screen turns off so just make Tasker turn the screen off when power is disconnected and voila

 

I didn't mention that app because I haven't personally used it, but I didn't realize that a fully-functional (at least, for a car-install) version was free! I'll probably end up using that for my install as well.

 

Updates on my end: still having USB connectivity issues... I think it's my Y cable. Ordered a new one, along with a pair of relay boards from. Should all be here by the end of next week. Hoping it wasn't my relocation of the USB port that's causing the issue.... I'm fairly confident it's not, since the tablet has no problem working with my computer/laptop, or even with my SD card reader or Tactrix OP without the hub in the mix.

 

Speaking of the USB port relocation, here's a couple pics. I've got quite a bit of experience with surface-mount soldering and rework, so this was a quick task for me (from pulling the tablet out of the box to buttoning it back up, was about a 30min task including disassembly, rework, and clean-up). I mangled one of the traces, luckily it was just the OTG trace. Repaired that by following it back until the first via/test-point and soldered a jumper wire in between.

 

Pro-tip in case you want to do this: be careful on desoldering! Add enough leaded solder (63/37 or 60/40 is fine) to make the joints easy to work with, then use wick to suck all the ground joints clean. Then add a bunch of solder to the 5 pins (bridge them, it's fine), and heat it all up until the jack comes off the board. Be careful, too much heat and you'll ruin traces and make the task much harder. Once the jack is off, clean everything up with wick, again, being careful not to rip a trace off the board or bend any pins. To bend the pins 90deg, I just used a flat-edge (pliers, ruler, etc), dug in between the plastic of the connector and the pins, then made sure to bend evenly and slowly. Once that's good, the best method of resoldering is to TACK DOWN THE SIDES FIRST. I know better, but was impatient and went to soldering the pins first. The best way is to add some solder to one of the side ground connections, then line up the jack with the board, heat up the solder, and remove heat after the jack is perfectly positioned. Let it harden, tack down the other side solidly, re-solder the first side, THEN solder the pins down. Use plenty of flux if you need it.

 

Desoldered:

http://i.imgur.com/eTwH3zo.jpg

 

Soldered at 90deg:

http://i.imgur.com/nLpJuyO.jpg

 

Hotglued (I bought a high-temp hot glue gun! yay!!) for mechanical rigidity:

http://i.imgur.com/JPnqAlu.jpg

 

Buttoned up:

http://i.imgur.com/nuBkfKQ.jpg

[Shogun506]

Hey guys just leaving a quick video clip of my final product:

 

Good luck with your installs!

[battelready]

Looks great and good thing you're not OCD like me or else those strips around the edge would've drove me crazy.

[Shogun506]

Yeah they aren't perfect - with the cold weather they became more evident, but the only one that bugs me is the bottom one and that's because I accidentally scored the bottom of the bezel with my dremel when I was making it. I might replace them with something else at a later date but it beats paying $200 for a JDM bezel and does the job for me.

[battelready]

Yeah they aren't perfect - with the cold weather they became more evident, but the only one that bugs me is the bottom one and that's because I accidentally scored the bottom of the bezel with my dremel when I was making it. I might replace them with something else at a later date but it beats paying $200 for a JDM bezel and does the job for me.

 

True. I tried doing what you did originally but i messed up the bezel so i just ordered a jdm one. Maybe you can find strips of plastic that can fit there .

 

Like this perhaps but in the color .

[ame=http://www.amazon.com/KYDEX-Sheet-0-028-Thick-Black/dp/B00KDMLJ0A/ref=sr_1_12?ie=UTF8&qid=1454193348&sr=8-12&keywords=plastic+sheet]http://www.amazon.com/KYDEX-Sheet-0-028-Thick-Black/dp/B00KDMLJ0A/ref=sr_1_12?ie=UTF8&qid=1454193348&sr=8-12&keywords=plastic+sheet[/ame]

[solidxsnake]

True. I tried doing what you did originally but i messed up the bezel so i just ordered a jdm one. Maybe you can find strips of plastic that can fit there .

 

Like this perhaps but in the color .

http://www.amazon.com/KYDEX-Sheet-0-028-Thick-Black/dp/B00KDMLJ0A/ref=sr_1_12?ie=UTF8&qid=1454193348&sr=8-12&keywords=plastic+sheet

 

All you really need is something to jig some body filler or epoxy and hold it in place until it cures. Then just dremel/sand it to fit. Which was what I was originally trying to do, but was getting impatient. The JDM bezel is so much cleaner, and I wouldn't be able to live with a non-stock-looking install. Granted the JDM bezel isn't a perfect fit. Maybe that'll motivate me to shape the stock USDM cubby bezel I started chopping up

[Windza]

Dang it...

 

If you can, could you post close-up pictures of the 'rear' of the bezel with the nexus in place? This way, I'll see how you modified the bezel, held the nexus in place, and took care of the usb port. That'd be great.

 

 

Hey sorry mate... got busy and haven't been hanging around the forums too much.

Unfortunately I won't be getting any close-ups of the rear anytime soon... the assembly is installed and doesn't like coming out! Thankfully I've only had to pull it once after full install but I was on eggshells the entire time!

If I end up having to pull it again, I'll make sure to take some pics and post them up.

 

Truth be told though, I'm not sure how much help they'd be because I think every install is going to be different depending on what you have available and what you like to work with...

My preference was hot glue because it's so easy to work with but it also comes with challenges ensuring you get a solid bond.

 

Just be prepared to do a lot of dremel work on everything... a scalpel or sharp knife helps with final trimming too.

You'll need to cut ducts, bezel and even the horizontal vent fins if you want the screen to sit flush against the bezel.

 

Also, before I started mounting the tablet, I started having issues with the touchscreen - I was able to fix that but it did make me decide it'd be better to hard mount a Nexus 7 shell case rather than the device itself.

That way, I can simply pop the old out and new in if something ever goes wrong in the future (broken screen, hardware failure etc.).

I ordered [ame=http://www.amazon.com/gp/product/B00EE1G6VI?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00]this shell case[/ame] for $7 (I have Prime) and cut the front cover off - it's a nice tight fit and secured in place very well. I do have peace of mind knowing I can put new tablet perfectly in place inside 30 seconds (that exclude the 45mins it'd probably take to get the assembly out of the car!).

 

In terms of the USB cord, I already had a 90 degree OTG adapter that I used - I didn't relocate the port or anything, just removed a vertical vent fin and called it a day... unless you knew to look, you wouldn't notice.

Edited January 31, 2016 by Windza

[Windza]

Just an FYI for anyone using the USDM nav bezel style - if you've already done the install, you know the bottom ~125 screen pixels get covered by the lower trim and you lose the native Android navigation bar (unless you're willing to do more dremelling and trim work).

 

I've seen where others configured gestures or navigation bar mods to workaround this but I tried various options in this vein and while you can restore some functionality, there is still some compromise and for the most part it felt half-assed to me.

 

I figured there had to be a way to tell Android not to use those pixels and it turns out there is.

If you've already gone through the motions of installing Timur on your Nexus, the fix is a walk in the park.

 

Simply open up your command window, connect to your device and run the following ADB commands;

 

adb shell wm size 1075x1920

adb shell overscan 125,0,0,0

 

Basically we've just told Android that it only has 1075 of the 1200 pixels available to work with and that those pixels are offset by 125 from the bottom edge (which is actually the left edge of the Nexus).

I've only been using this for an hour or so at time of writing but it appears setting Android up like this means everything runs natively at that resolution so there is no compromise with scroll bars going off screen, aspect ratios etc.

An added bonus is that the change persists after reboot as well, so no messing with a boot script or Tasker to make it stick!

WIN!

 

Depending on your own install, those numbers can be tweaked to whatever you want to get the alignment perfect or even put a small 5 pixel border around the perimeter to help with swiping in from the edge of the screen (for things like notification drop down).

 

Also, if you happen to mess something up, you can reset things back very easily with

 

adb shell wm size reset

adb shell wm overscan reset

 

Now I'll just wait for someone to tell me that this was mentioned in a previous post that I missed :-)

[Windza]

Here are some pics of the results (the gray border is deactivated screen area and is barely noticable - the photos make it standout).

 

Seems you can just use

adb shell wm overscan X, X, X, X

 

without setting resolution.

 

I ended up using

 

adb shell wm overscan 130, 5, 5, 5

 

Absolutely stoked that this works so well!

Ideally I'd love to have the JDM bezel but this saves me $200+ and I'm not about to lose any sleep over the loss of screen real estate.

[Squishy808]

Is Timur still active - I sent him an email inquiry cuz I just didn't want to send money without being sure. I have a N7 2013, so autodroid is out. I know his 2012 rom is out there, but I am already invested and ready to go with the 2013 :[

[solidxsnake]

Is Timur still active - I sent him an email inquiry cuz I just didn't want to send money without being sure. I have a N7 2013, so autodroid is out. I know his 2012 rom is out there, but I am already invested and ready to go with the 2013 :[

 

I'm not sure. If you can live with rebooting or unplugging/replugging your devices (for now... I'm working on how to get this to work correctly), I'd use Glitch or ElementalX with your choice of ROM (I'm on the latest SlimLP beta with Glitch r412, running /data and /cache as f2fs with an ext4 /system partition).

 

The only problem I have currently is the tablet refuses to re-enumerate USB devices if power is lost on them (need to reboot or unplug and re-plug the USB cable). I think my next step is to rebuild the Glitch kernel with the USB drivers as a module instead of a built-in driver, so I can unload and reload the module on command. Not sure if this will work, but it's worth a shot

[xt2005bonbon]

Here are some pics of the results (the gray border is deactivated screen area and is barely noticable - the photos make it standout).

 

Seems you can just use

adb shell wm overscan X, X, X, X

 

without setting resolution.

 

I ended up using

 

adb shell wm overscan 130, 5, 5, 5

 

Absolutely stoked that this works so well!

Ideally I'd love to have the JDM bezel but this saves me $200+ and I'm not about to lose any sleep over the loss of screen real estate.

 

 

Thanks Windza for relocating all your info in this thread. Another question for you. Can't remember if you mentioned this or not: do you retain full usage of your vents?

 

 

Also, for anyone in here, which USB DAC are you guys using and what kind of issues are you encountering if any? How is the noise level compared to analog?

[solidxsnake]

Thanks Windza for relocating all your info in this thread. Another question for you. Can't remember if you mentioned this or not: do you retain full usage of your vents?

 

 

Also, for anyone in here, which USB DAC are you guys using and what kind of issues are you encountering if any? How is the noise level compared to analog?

 

I'm using the Behringer UCA202. Haven't run into any compatibility issues related to the unit. Sound quality is much greater than analog (at least with grouper; I haven't tried the analog out on flo), since no digital noise from the CPU/GPU/etc. is induced in the USB DAC. Also was cheap off Amazon (I think like 25-30 bucks?).

 

Keep in mind that if you're powering your USB devices with a non-isolated supply, you can still get noise on your output, unless your DAC is specifically designed otherwise (which I would assume most are not). I can tell you that with the UCA202, noise on the USB COM line propagates to the audio output. This is why I built myself an isolated 5V converter. I still get noise if I plug my Openport into my hub though, since the Openport 2.0 doesn't isolate the OBD COM from the USB COM :spin:

[xt2005bonbon]

^ That's annoying. So one may eliminate noise from the tablet, but then gain some from auxiliary USB devices .

[solidxsnake]

^ That's annoying. So one may eliminate noise from the tablet, but then gain some from auxiliary USB devices .

 

It's possible, but unlikely. As long as you've got a good isolated supply, then you should be good on the noise front. If you don't, I can almost guarantee you'll get noise on the audio line, unless you've got a very high quality DAC, but even then, you'll need to make sure you power the DAC with a clean 5V supply (using the car's COM is a no-no).

[heiche]

I'm not sure. If you can live with rebooting or unplugging/replugging your devices (for now... I'm working on how to get this to work correctly), I'd use Glitch or ElementalX with your choice of ROM (I'm on the latest SlimLP beta with Glitch r412, running /data and /cache as f2fs with an ext4 /system partition).

 

The only problem I have currently is the tablet refuses to re-enumerate USB devices if power is lost on them (need to reboot or unplug and re-plug the USB cable). I think my next step is to rebuild the Glitch kernel with the USB drivers as a module instead of a built-in driver, so I can unload and reload the module on command. Not sure if this will work, but it's worth a shot

 

This would be quite an accomplishment! You could become the N7 kernel go-to guy

[Windza]

Thanks Windza for relocating all your info in this thread. Another question for you. Can't remember if you mentioned this or not: do you retain full usage of your vents?

 

 

Also, for anyone in here, which USB DAC are you guys using and what kind of issues are you encountering if any? How is the noise level compared to analog?

 

So I removed the 2 innermost vertical fins for clearance and notched a few horizontal fins and a section of linkage. I retain full movement/use of the vents with the exception of horizontal direction on the RH vent which is restricted to ~1/4” movement. Considering I haven't been a passenger in any of my vehicles for years, I'm OK with that ;-)

 

In terms of audio, I went with the Behringer UCA202 DAC because it seems most everyone has had success with it... I did have some background static/noise that was completely eliminated by this device;

https://www.amazon.com/gp/aw/d/B0171PQLB8/ref=ya_aw_oh_bia_dp?ie=UTF8&psc=1

I was very impressed with the difference it made - night and day. If I crank the volume while nothing is playing you might pick up some faint noise while things are powering up but otherwise its perfect for my needs.

[Stryx]

I'm not sure. If you can live with rebooting or unplugging/replugging your devices (for now... I'm working on how to get this to work correctly), I'd use Glitch or ElementalX with your choice of ROM (I'm on the latest SlimLP beta with Glitch r412, running /data and /cache as f2fs with an ext4 /system partition).

 

The only problem I have currently is the tablet refuses to re-enumerate USB devices if power is lost on them (need to reboot or unplug and re-plug the USB cable). I think my next step is to rebuild the Glitch kernel with the USB drivers as a module instead of a built-in driver, so I can unload and reload the module on command. Not sure if this will work, but it's worth a shot

 

Looking forward to hearing these results! Based on bonbon's input I'm guessing Timur's ROM does not fix it either.

 

The Limefuel pack worked great up until yesterday using 1A out. Now the passthrough on the pack is hit or miss, as if the chip is confused. (Display goes wonky as the pack tries to decide what to do for several seconds at a time). Haven't decided if Im going to get it replaced or see if it can be modified to suit my needs.