Using custom ROMs on Android devices

[Brian Fist]

Hey guys, I figured I would start a new thread and try to keep it on topic...

I have a Samsung Galaxy Tab Pro 8.4, which has a 2.3Ghz quad-core processor which is plenty fast to run the DJI GO 4 app.

Now under the stock 4.4.2 ROM, the app runs, but it has issues. It has the broken video feed issue a lot of tablets have, and it also crashes at times. One example is trying to do a firmware update. It downloads and then gets to between 5% and 6% and then crashes. (I have been able to update the bird with DJI Assistant 1.1.0 on my laptop, for reference)

Another is at times when trying to exit the app the "press again to exit" overlay was stuck on the screen and the app wouldn't end on it's own, I had to kill it in the task manager.

Since I really don't want to deal with the app crashing while flying and I believe tear-free video is a priority, I went all-out and reset the tablet, then deleted everything off it I could short of rooting it. I disabled auto updates, sync, uninstalled all the apps I could, etc, etc...

Nothing fixed the disconnection and firmware upgrade issues, the video tearing persisted and the "stuck" app still remained. In the end it is obvious that Samsung has hobbled this device because it basically is just about as good as anything else they have released since. There is no way to remove all the Samsung bloat and I am determined to get this thing stable for use with my P4P.

So, we enter the realm of custom ROMs.

Now, I looked high and low and there is a lot of development for the SM-T320 (model code for the Galaxy Tab Pro 8.4), but nothing I could consider wanting to "waste time" dealing with, especially with CyanogenMod now gone. That was until I came across SlimRoms.

It just so happens they have a "stable" custom rom based on 6.0.1 Marshmallow. And not just a single stable release, but also a second stable release with known security fixes and optimizations. Now in reading a lot about the DJI GO 4 app and it's issues, it seams that Android 7.0 Nougat is something of a dice-roll if your device will work or not with it, but almost everyone says Marshmallow 6.0 just flat out works, so that was where this seemed to be a "perfect fit".

Installation requires rooting, no biggie since there are plenty of tools/guides out there. I installed the TWRP recovery, then I loaded the custom ROM and the "pico" varient of the gapps.

First installation I just cleared the data/cache/davlik, installed the ROM and the gapps and then rebooted.

On the first setup it got stuck on looking for WiFi and the formatting of the SD card caused a reboot. Not a good sign. But I remember that when I went to select the ROM and gapps to install it still showed a ton of previous data on the internal storage, and since I wanted to start "fresh", I decided to reload the SD card with the ROM and gapps from the laptop, then boot into recovery and this time I told it to wipe EVERYTHING. I manually selected everything but the external SD card.

Once the complete wipe was done I reloaded the custom ROM (I used stable 2.0, fyi) along with Pico gapps.

This time the boot not only optimized the apps quicker, it also didn't get stuck on finding WiFi, and formatted the SD card without issue. I can only assume the previous data was causing issues.

So, I finally got to set everything up, I told it NOT to sync anything, went and installed Google Maps, made sure the GPS was working on High Accuracy and the maps pulled up (and I noticed right away it was absolutely BLAZINGLY fast compared to the stock OS), then installed B4UFLY and then DJI GO 4.

I can't stress enough how quick everything runs and how smooth it all works on this ROM compared to stock. Night and day.

I have yet to try it with the bird, but I will be doing that tomorrow and I will report back with my findings.

Oh, I also changed one of the settings in regards to the display, that being the LCD DPI. I switched it from teh default 280dpi to 360dpi. The device has a screen density of 359ppi (pixels per inch) so I figured the 360dpi setting was darn close.

The outcome being that all the text and icons were increased in size. The display is MUCH more readable and it would seem as if that was the way they designed the app to be optimal. Before the text was a bit too small in menus and settings. The screen is also easy to switch brightness with their built-in quick-bar that lets you turn various items on/off and change levels for others (such as WiFi, bluetooth, GPS accuracy, sync and screen brightness)

If everything works out, I am hoping that this might just be an ideal setup for use with DJI GO 4. It has double the speed of the Nexus 7 (2013 version), 31% more screen area, and overall should be plenty for the DJI GO 4 app.

As a side note, it would seem that this ROM also has outstanding battery life. I was on 37% at 9:17 and almost an hour later it is at 34%, and that is with WiFi, bluetooth and GPS active and it sitting in maps.

 

[The Springs]

I have a Tab s 8.4 and have rolled the os back to 5 due to Litchi/GO problems but its still not quite right.So I will be keen to hear how you go with this ROM

 

[David Seda]

Cyanogen mod has just become lineage OS, it's not gone as I purchased a nexus 7 2013, rooted it and have Android 7.1.1 on it. Nougat runs dji go app excellent.

Just a heads up the nexus has plenty of speed to run the dji go 4 app. As a matter of fact the speed difference is negligible between my galaxy tab e, my Galaxy s7 edge and my nexus when it comes to the dji app speed or latency.

One thing you'll be losing is the brightness as the nexus 2013 has the brightest of any Android tablet out to date.

Cyanogen = Lineage OS now

 

[Brian Fist]

The problem is the Nexus 7 (2013) isn't available. The used ones you find are chipped/cracked/etc... And to spend $125-150 on a "good one" is crazy considering the battery is old and at that point you might as well buy a nVidia Shield K1.

I started this thread because almost ALL Lineage and CM builds are not listed as "stable". I for one have 5 kids, tons of responsibility and it is crazy to just install nightlies and "hope" they don't compound the problems that DJI GO 4 has on so many devices. The idea here was using known STABLE builds that aren't a crap shoot.

There are those of us that are not finding ANY reasonable info on stabilizing usage of Android tablets for use with our drones and this was meant for that.

Fact of the matter is that people will use what they have, if they are reasonable. I have a Galaxy Tab Pro 8.4, Note 10.1 2014, Note Pro 12.2, 2 S5s and a S3 as well as a few Nexus S and a 2012 Nexus 7 at my disposal. Given that collection of hardware, the Tab Pro 8.4 is the natural choice for use with my P4P for size/usability. It doesn't make sense to spend another $150-200+ on more hardware when I have plenty on hand already.

 

[DanMan32]

I'd be interested if this works on a Tab E 9.7 Wi-Fi only with Go3, Airmap, B4UFly, video player, OneDrive. My biggest problem is getting the Tab to connect to the RC without hassle, reception issues and video lag not always appearing to be reception related.

 

[David Seda]

The nexus is available. I found one on ebay in perfect condition for 85 bucksa few weeks ago. No scratch no dings or dents or cracks.

Lineage OS runs perfectly with everything working at least on the nexus.

I also have a galaxy tab e which has a nice big screen but the brightness is lacking.

I brought up lineage because you said cyanogen no longer exists, which is false, it just exists under a different name.

For maximum screen brightness and lineage I brought up the video I just posted that is in fact running lineage os. Sorry if my video offended you. But you can get a good working nexus 7 2013 for well under what you have stated, and run a good custom rom on it with it working perfectly as I haven't had any crashes yet. Also the nvidia shield doesn't have the screen brightness. Actually no Android tablet has the same brightness as the nexus 7 2013. But if you have it on hand use it.

As far as dji go having problem on many or several devices as you've stated, I've tried on 4 different android devices, one with a custom rom (lineage) and stock roms and haven't had a problem with crashing.

Honestly my Samsung tablet has a problem connecting to the Rc on boot up, but cycling the Rc seems to fix it.

I get people will use what they have, but 85 bucks is reasonable for a super bright Android display which I have designated strictly for flying. Just trying to help.

Ive removed my video link and have left the rest, because lineage at this point in time is quite stable on most devices. FYI nightlies are considered stable unless stated otherwise by the rom developer.

 

[Brian Fist]

In regards to SlimRoms, at this time i cannot recommend it. Two major issues reared their head and both are somewhat of a deal-breaker.

First is the fact that battery charging on the Tab Pro 8.4 is problematic under Marshmallow. It took it almost 10 hours to fully charge and when booted at 93% the OS showed "Slowly Charging" as a status, which is a known issue. Considering the tablet charged fully in 4-5 hours before, to wait twice as long doesn't make sense. It may resolve after the first recharge, but it is quite disconcerting to have it happen at all.

Second is the fact that DJI GO 4 ran great, that is until I went to exit out of it. I mean the app performed flawlessly while running the drone, it flew great, no video tearing, menus were responsive, etc, etc... But trying to exit out of it caused a freeze. I mean I couldn't even hit the DJI logo at the upper left and go back to the main screen it would freeze. Now this could just be an app issue and they could resolve it in a future release, but I won't go out flying with it like this.

So my next step is to find a stable release of Lollipop 5.1.1. From what I can gather LineageOS/CM never really got everything working properly for the Tab Pro 8.4, as there is still outstanding issues in the notes for CM12.1 on this device. But considering there are tons of ROMs out there, I am not throwing in the towel just yet. The responsiveness of the tablet under SlimRoms 6 was just outstanding.

David, thanks for the clarification. And, don't get me wrong, the Nexus 7 2013 is a great option if it is available, but I am sure a LOT of people are like me, with other various Android tablets and it only makes sense to be able to task one of them with dedicated drone use.

 

[David Seda]

In regards to SlimRoms, at this time i cannot recommend it. Two major issues reared their head and both are somewhat of a deal-breaker.

First is the fact that battery charging on the Tab Pro 8.4 is problematic under Marshmallow. It took it almost 10 hours to fully charge and when booted at 93% the OS showed "Slowly Charging" as a status, which is a known issue. Considering the tablet charged fully in 4-5 hours before, to wait twice as long doesn't make sense. It may resolve after the first recharge, but it is quite disconcerting to have it happen at all.

Second is the fact that DJI GO 4 ran great, that is until I went to exit out of it. I mean the app performed flawlessly while running the drone, it flew great, no video tearing, menus were responsive, etc, etc... But trying to exit out of it caused a freeze. I mean I couldn't even hit the DJI logo at the upper left and go back to the main screen it would freeze. Now this could just be an app issue and they could resolve it in a future release, but I won't go out flying with it like this.

So my next step is to find a stable release of Lollipop 5.1.1. From what I can gather LineageOS/CM never really got everything working properly for the Tab Pro 8.4, as there is still outstanding issues in the notes for CM12.1 on this device. But considering there are tons of ROMs out there, I am not throwing in the towel just yet. The responsiveness of the tablet under SlimRoms 6 was just outstanding.

David, thanks for the clarification. And, don't get me wrong, the Nexus 7 2013 is a great option if it is available, but I am sure a LOT of people are like me, with other various Android tablets and it only makes sense to be able to task one of them with dedicated drone use.

Absolutely... I agree though that finding a good stable rom would be best without all the BS thrown in with the system.

Have they upgraded to 14.1 on the Samsung tab? I haven't rooted a Samsung device in a while because the bootloader is typically a pita to unlock.

Only issue with the Samsung I have experienced is the whole restarting the Rc problem.

If you come across CleanRom I'd give that a try if it exists. A totally debloated stock firmware may have luck [emoji256]

 

[smiller]

Samsung has done a good job wrecking the Android OS with it's crappy UI modifications and bloatware. Most problems I see reported seem to be with Samsung products and it would appear that the closer you stay to the pure Android OS the better you will be. It is trivially easy to unlock a Nexus 7 2013 and load any pure Android OS version you like. I use 6.0.1 and the combination works very well as a dedicated DJI GO 4 / Litchi platform (I use both and I have no problems with interaction.) The Nvidia also garners good reports but I have no personal experience there. I can say that the Nexus 7 2013 is a great platform for DJI/Litchi and a great bargain as well if you can find a clean one, one of the brightest tablet screens as well. Mine is several years old but the original battery is going strong, but replacement is not difficult it it comes to it by removing the back (you do not need to disturb the screen.)

 

[Brian Fist]

Well, I had a bunch of stuff going on with some of the kids today, but I was able to fit in some ROM loading and testing...

First I tried was the LineageOS version of 6.0.1. No luck, it was exactly the same result as SlimRoms. Total freeze on exiting of the app.

So I then downloaded the latest "stable" compile of 5.1.1 Lollipop and the associated Pico gapps, and then decided to grab the 3/19 build of Lineage 14.1 aka 7.1 Nougat along with it's associated Pico gapps...

Things got busy making dinner, getting everything set up for "movie night" with the kids, so I said screw it and loaded 14.1.

Well, that went way better than I hoped, no issues, seemed totally smooth, basically only the camera and flash don't work. I loaded on Maps, B4UFLY and DJI GO 4. Got everything setup, disabled sync, optimized a few more OS parts, setup the P4P, plugged it in and started the bird and controller. It set the default properly, went in, detected firmware and gave the the "GO FLY" option.

I got into the controller and I had good video feed, no tearing. Everything looked good on all the menus, so I tried exiting. Lo and behold I was able to exit back to the opening screen. I went back into flight mode, even using the DJI button at the upper left worked as it should.

Now I still need to test battery charging, so I am draining the tablet as I type this. But, if it charges properly it looks like we might just have a winner.

Personally, I could care less about the camera and flash, but I am sure at some point they will get them working. If charging doesn't work properly I always have 5.1.1 Lollipop to try, but obviously I would prefer 7.1 Nougat for long-term use.

 

[David Seda]

Well, I had a bunch of stuff going on with some of the kids today, but I was able to fit in some ROM loading and testing...

First I tried was the LineageOS version of 6.0.1. No luck, it was exactly the same result as SlimRoms. Total freeze on exiting of the app.

So I then downloaded the latest "stable" compile of 5.1.1 Lollipop and the associated Pico gapps, and then decided to grab the 3/19 build of Lineage 14.1 aka 7.1 Nougat along with it's associated Pico gapps...

Things got busy making dinner, getting everything set up for "movie night" with the kids, so I said screw it and loaded 14.1.

Well, that went way better than I hoped, no issues, seemed totally smooth, basically only the camera and flash don't work. I loaded on Maps, B4UFLY and DJI GO 4. Got everything setup, disabled sync, optimized a few more OS parts, setup the P4P, plugged it in and started the bird and controller. It set the default properly, went in, detected firmware and gave the the "GO FLY" option.

I got into the controller and I had good video feed, no tearing. Everything looked good on all the menus, so I tried exiting. Lo and behold I was able to exit back to the opening screen. I went back into flight mode, even using the DJI button at the upper left worked as it should.

Now I still need to test battery charging, so I am draining the tablet as I type this. But, if it charges properly it looks like we might just have a winner.

Personally, I could care less about the camera and flash, but I am sure at some point they will get them working. If charging doesn't work properly I always have 5.1.1 Lollipop to try, but obviously I would prefer 7.1 Nougat for long-term use.

Nougat has been a joy for me to use so far! And not for nothing, if you're using the tablet for flying who cares about the camera?

Glad you had time to tinker and try it out. It's nice and snappy to boot!

 

[Brian Fist]

I agree, it is fast as all hell...

So, it is OBVIOUS that the tablet manufacturers bog down just about every device out there to sell newer devices. What a sad, sad situation.

I mean once you have a reasonably fast quad-core tablet with at least 2gb of RAM and a decent display, why the heck would you need to upgrade?

It is just sad that there is such a push to obsolete tech so quick to sell new products. I mean I just upgraded my 2010 rig (x58 chipset, 24GB ram, new GTX980 video card from dual GTX480s, added a SSD) and installed Windows 10 and even Intel is on the bandwagon to kill off all the older tech out there by not offering something as simple as chipset drivers. I mean c'mon! I mean you can buy brand new processors that will drop into a board like mine and they run just great. People have even provided updated ROMs that include newer controller firmware and CPU microcode to run newer processors. But the manufacturers can't wait to drop support to force people to spend money. Hell some even hamstring their products with updates that do nothing but hinder performance, or worse, kill off hardware (there was a set of drivers that literally killed off GTX480s left and right, all because two or three in SLI would "hang" with the latest cards for most games).

But, in regards to tablets, there definitely seems to be a "wall" in regards to performance and capabilities, so holding back with firmware updates is all they can do to force people to buy newer products, or even when they do offer a update for "security reasons" they end up screwing it up so that the performance drops. How sad.

Now the aforementioned 2012 Nexus 7 I have is running on 6.0.1 from Google and it is a slow pig, but that is because it is pushed way beyond what the hardware is capable of. That tablet, left on 4.4.4 was a solid device, ran well and snappy and didn't show any of the issues seen since 5.x...

 

[David Seda]

When I picked up the 2013 model, I read that Google stopped giving it updates past marshmallow. Proceeded to root and all is well... I really enjoy it but that's what these companies want... More and more money

 

[smiller]

Now the aforementioned 2012 Nexus 7 I have is running on 6.0.1 from Google and it is a slow pig, but that is because it is pushed way beyond what the hardware is capable of. That tablet, left on 4.4.4 was a solid device, ran well and snappy and didn't show any of the issues seen since 5.x...

Just to clarify for those not familiar, the Nexus 7 2012 and the Nexus 7 2013 are two very different models. The former is generally considered inadequate for DJI GO while the latter has a much faster processor and higher res screen, and while not leading edge these days it still performs quite well with DJI GO/Litchi.

And yes, while the N7 2013 performs well under 6.0.1 the N7 2012 is better left at 4.4.4.

 

[Brian Fist]

Actually, I spent some time modding my "extra" tablets and I can attest that the Nexus 7 2012 runs 7.1.1 Nougat just fine.

I have LineageOS 14.1 aka Nougat 7.1.1 on it along with just Maps and DJI GO 4, and I turned off all notifications/sync/etc. It works just fine. (as a side note I disabled local caching of recorded video, since the N7 2012 is known for slow memory speeds, so I figure why stress it). The N7 2012 also has a decent quad-core processor and video chip in it, it is just the flash memory they used is slow compared to what everyone used even a year later. So any sort of issue with performance is solely associated with the flash memory. Once the device is up and running and "stabilized", it is just fine for limited usage like DJI GO 4.

Now, I completely plan to use my Tab Pro 8.4 as my main flying device, but it is nice to know I have a backup with the Nexus 7 2012 as well.

 

[David Seda]

I have video caching disabled on the nexus 7 2013 because I only have 16gb version. But I supposed it has the power to hold onto a couple of gigs of video if needed. But like you said why stress it? I hardly ever use it. Glad you've found lineage to work successfully for you!

 

[Brian Fist]

Oh, forgot to mention, the Samsung Galaxy Tab Pro 8.4 charges just fine under 7.1.1. None of the weirdness I noticed under 6.0.1.

It just takes it a good full charge, full discharge, full charge again to start showing proper battery life. At first it seemed to be draining way too fast and then you would plug it in to charge and it would show 30% right away. after it charged up the battery life was a little better, but still seemed to drain fast. The second recharge after a full charge and drain showed 28% to start. But now that it is fully charged I have had it turned on for the past 11 hours or so and it is showing 94% battery available, so I do believe it has finally "calibrated" the battery.

Now I have to go through that same song and dance with my Nexus 7 2012. I am currently trying to figure out the wifi issues that tablet though, as it is fine in the house, but in the garage it shows full signal strength but streaming music it breaks up. I popped the back off and readjusted the "fingers" to the wifi antenna in the caseback and hopefully after it charges it will be better. Even with the stock ROMs wifi has always had issues on that tablet.

 

[Brian Fist]

Well, I figured I would follow-up and as it turns out either the current DJI GO 4 4.0.5 Android app, or the 7.1.1 ROM itself has issues. The DJI GO 4 app just basically exits at random times while flying. Now it isn't as bad as it sounds since I can just go right back in and reconnect, but it is still far from what I consider "stable".

So, back to the quest for a valid ROM. I will see if there is an updated 7.1.1, but I figure I might just hunt down a "known good" 5.1.1 Lollipop ROM. I do know they got Lollipop running perfect on this device at one point, including the cameras and everything else, so that might just be a good place to start.

 

[Brian Fist]

To be honest, NONE of this would be necessary if DJI would hire some decent Android coders and make sure their app just "works".

I mean c'mon, look at how many complex android apps there are and they run without crashing and all the other BS so many of us run into. They can't even get their OWN android system stable on their Pro+ controllers.

 

[Brian Fist]

Another follow-up:

So, after my disappointment with 7.1.1 (which, as it turns out, I am not alone, as the nVidia Shield K1 guys have the EXACT same issue of the app just exiting mid-flight), I got a hold of the two *latest* and best 5.1.1 offerings for the Galaxy Tab Pro 8.4. One is a SlimRoms unofficial build, the other is a CyanogenMod 12.1 build.

Since I have heard that the CM 12.1 build is "rock solid" on my tablet I went ahead and loaded that one along with the Pico Gapps for it. Got it all setup, tweaked the OS for battery, loaded on Maps, DJI GO 4, B4UFLY and Kodi (the latter to watch video via a OTG Micro SD adapter on the tablet itself once I am done shooting footage, which I find is easier than swapping out MicroSD cards inside the tablet itself), got all the quick-bar stuff setup for my use while flying and then did the dreaded drain/recharge/drain/recharge cycle to establish a battery calibration. I may add that if you do not do that the battery calibration is way off and you won't get the full battery usage.

Well, first off there is ZERO issues charging the battery under 5.1.1. There is also no issues with any of the built-in cameras, sensors, wifi, bluetooth or USB port. I also get full video acceleration under Kodi and the OS just flat out works with nothing running when nothing is supposed to be running.

Now, I can say that in all my testing with the P4Pro I have never been able to say that the video feed is "stable" indoors. I always have issues with 2.4GHz indoor because I have 4 wifi routers/APs running with 6 radios sending/receiving on ALL the 2.4GHz wifi bands and at least 32 of the 5GHz bands. Now those channels are all spread out, but I still have a hard time finding channels that work on the P4Pro and even when I do I can't say they have been "solid" in the past. Auto channel mode was almost always wrong.

And, trust me, I understand that all of this is in the controller and bird itself, and that a tablet connected should have zero to do with it, but I am sure we all know that the tablet connection video is more than flakey at times and we can't just attribute it to the controller/bird comms, in that it has to do with the Android OS/app/USB throughput combo more than anything at times. Especially in the face of a "good" signal reading from DJI GO 4 and/or the absence of any interference while outdoors.

But, this time, under 5.1.1, when I had a "good" signal rating I had absolutely FLAWLESS video feed. I mean I left the bird up in the loft on the second level of my home and went down to the computer center/theater in the basement and then back into the utility area and had ZERO breakups/pixellation. Now for reference my house is constructed in an "overbuilt" manner with all treated lumber, 1" thick drywall and 1/2-3/4" textured plaster over the drywall, Italian tiled floors on the main level with 3" thick concrete with two layers of wire mesh imbedded into it, etc,etc. (Now you know why I have 4 routers/APs running, and stud finders are basically useless with the plaster)

And that was with the radio set to Auto 5.8GHz. I tried manual channels and every one that showed a "good" signal was flawless as well.

I might add that ALL the features of DJI GO 4 worked, for the first time ever, including the simulator, firmware updater, entering/exiting, all the menus, etc.

I will be doing some flying tomorrow morning, but I am hoping I have found a perfect combination. If so I have to start looking for a decent hood/screen-shade that will fit the Galaxy Tab Pro 8.4. As it is I have a matte screen protector I am probably going to install that I have been holding out on just in case I couldn't get anything stable going.

Oh, I may add that in doing further research I found that the controller built into the P4Pro+ model is ALSO running 5.1.1... Kinda makes sense if that it their target OS revision that it would work flawlessly under it.