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Snorkler's astronomy-optimized Nexus 7 (Android)

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#1 snorkler

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Posted 29 October 2012 - 03:00 AM

I have my Android-based Nexus 7 working about as well as I ever imagined a tablet could work, so I thought I'd share what I've done with all of you. If this spurs some of you on to share what you've done with your tablets for astronomy, then we'll all be richer for the experience.

First, here's my setup on July 18, shortly after I received my 8gb N7.
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The home screen wallpaper is my photo of a Black-browed Albatross, taken in Australia.

Next capture shows my current setup, with the wallpaper being my astrophoto of M42. I took the photo from my back yard in the light-polluted metropolitan San Francisco Bay Area of California, stacking about fifty 90 second exposures taken through a Meade Schmidt-Newtonian telescope.

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Notice the red navigation bar buttons at the bottom of the screen. They're white on unmodified N7s. I rooted (or jailbroke) my N7 and I'm running the Paranoid Android v. 2.50 ROM, which lets me customize the navigation bar background, button, and glow colors. V. 2.52, just released 27 October, is buggy, and either stops setup from working, or simply doesn't respond to nav bar button change attempts. So, if you try this on your Android, v. 2.50 is the version to flash. Versions prior to 2.50 didn't have nav bar color-changing ability.

Paranoid Android has some really neat features. Notice the day of the week and date are shown on the status bar in the second screen capture above. I don't know if you can customize the status bar with the stock 4.1.2, but I can do it in Paranoid Android.

Here's something I know isn't available in stock 4.1.2. The capture below shows my USB storage stats in Paranoid Android's Settings > Storage function. I added a 32gb USB flash drive to my N7 and partitioned it with the first partition having 28gb total space, and still have 16gb available - not bad for the $200 base model 8gb N7. I have a 40gb N7 for $225. In case you're wondering, I set aside 1.5gb in a second primary partition for future experimentation with moving apps themselves to the second partition
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I rooted my N7 as soon as guides for rooting the N7 came out. i'm keeping about 6gb of Nandroid backups, and 2.5gb of astronomy and birding app data files on a $20 USD 32gb USB flash drive (plus ~$4 for the USB-0TG cable, shipped), and I'm running those data-intensive apps while they're reading the data from the flash drive. Obviously, I can't do that without being rooted.

#2 snorkler

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Posted 29 October 2012 - 03:19 AM

I put a lot of work into optimizing my N7. I use the Screendim app to drop screen brightness well below the minimum stock brightness. i switch from my bread and butter Swiftkey 3 Tablet keyboard app to the Omegacentauri GB Keyboard app, because it has a red layout that's best for inputting in search target names to Sky Safari Pro. See the attached screen capture below. If I could only change the white magnifying glass icon to red...
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I use a sideloaded Directory Bind app to redirect my app's data queries from the N7's "external" 8gb storage to my 32gb USB flash drive.

Hsre's how my night-optimized N7 shows the naked eye view of Orion in red light. Actually, this view is much brighter than I use under dark skies. It and the previous capture are set this way so you can see them without going dark-adapted.
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I mentioned the data files for my astronomy and birding apps total 2.5gb. Since the 8gb N7 only has 5.92gb total space after the OS and OEM apps are loaded, and I'm using 1.9gb to store two Nandroid backups (my stock 4.1.2 and my Paranoid Android), those 2.5gb of data had to move outside to the USB flash drive. It took me a long time (see my 64 gigabyte question thread in the Nexus 7 forum) before other users there told me about the Directory Bind app that accomplishes this.

Sky Safari Pro needs 1.4gb of storage to store the specifications, locations, descriptions, etc. for its catalog objects.

My birding apps need 1+gb of data to store their 800 species illustrations, range maps, song and call recordings, and more. The following screen capture shows the Sibley Field Guide comparison function results for two species - Black-throated Gray Warbler and Townsend's Warbler. I'm looking at adult male and adult female comparisons, but juvenile comparisons and songs from several different states are typically available.
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Questions? Comments?

#3 Chucky

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Posted 29 October 2012 - 08:25 AM

Nice job!! You certainly have thought things through and put forth a great amount of time and effort into your configuration.

This Friday my new white Ipad Mini should be delivered. I plan to do the 'KISS' thing by simply installing SF, and putting a red film on the screen. This should wirelessly (SkyFi) integrate perfectly with my push-to Dobs/refractors on DM-4 alt/az mount. Kind of a 'no brainer'.

#4 rockethead26

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Posted 29 October 2012 - 09:07 AM

Hey, Snorkler! Nice job with the Nexus. That's something I'd like to do as soon as I can free up some funds for a new tablet.

#5 rboe

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Posted 29 October 2012 - 10:30 AM

Wow! :bow:

#6 Spaced

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Posted 29 October 2012 - 05:08 PM

Darrell, thank for sharing the fruits of your labors. After much study and navel-gazing I decided to acquire an iPad Mini (which I may order later today,) but I hope that none the less you'll be willing to try to explain a couple of my lowbrow, bonehead questions, despite my confession to allowing myself to be sucked into the Apple maelstrom.

You mention that you "rooted" a couple of your apps. I've seen the term a number of times before but don't understand. Would you be willing to explain?

I was going to ask a couple of questions about your flash drive setup but, having gone through some of your "Nexus 7" thread I think I now understand.

Finally, do I understand accurately that SF Pro and your large birding program together use about 6 gig of storage?

Thanks!

#7 btschumy

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Posted 29 October 2012 - 05:30 PM

Mike,

On iOS devices, SkySafari Pro uses 590MB of storage. It takes about twice that on Android due to the (somewhat screwy) way it requires us to package the large amount of data.

Bill

#8 snorkler

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Posted 29 October 2012 - 08:08 PM

Mike,

Android rooting is the same as iPhone and iPad jailbreaking. It simply gives the user access to, and control of, the system area of the mobile device. So, I rooted my Nexus 7, not its apps.

My flash drive setup uses a USB-OTG (USB on-the-go) connector. One end is a male micro USB connector that plugs into my N7. The other end is a female USB connector that accepts my flash drive, memory card reader, or other peripherals.

Nexus 7s do not support USB-OTG hosting natively. I had to root my N7 in order to enable USB-OTG hosting on my N7. Stock N7s can only read from devices connected to the USB cable. They're essentially at the end of a one-way street. Rooted N7s can read from and write to connected devices, so they're on a two-way street.

No, my astronomy and birding app data only amount to 2.5gb, I have ~6gb of Nandroid backup files. Since my 8gb N7 has less than 6gb of free OEM storage space, the utility of my 32gb flash drive is easily apparent.

#9 StarWars

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Posted 29 October 2012 - 08:40 PM



Cool little gadget... :bow: :jump: :jump:


For $225 I need one too but I have no idea how to get it working... :(

#10 snorkler

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Posted 30 October 2012 - 12:34 AM

Neither did I, when I first got mine. I was brand new to Android, and hadn't even used an Android cell phone. I joined the Nexus 7 forum after pre-ordering mine, and learned about the N7 and Android along with everyone else, even before getting mine in my hot little hands.

None of us knew how Android 4.1 Jelly Bean would look or operate. We learned together how to root our N7s. We shared knowledge about the most useful apps.

I think you can all see the attention to detail in my modifications. Some of the things you can't see. The minimum factory backlighting brightness is about 25%. Screendim lets me adjust it down to 0% brightness, plus allowing me to adjust the contrast. I have 3 preset night settings and 2 day settings, selectable by clicking on different widgets, so my lowest might be set at 3% brightness and 30% contrast, the next brightest at 6% brightness and 40% contrast. Night3 is a night reading setting for me to use in bed without disturbing Mrs. Snorkler. There's also a Screendim off widget to restore the brightness to regular function.

One of the best features of rooting is my ability to block ads.

I've also got the ability to edit PDF and MS Office files, to print to my home printer wirelessly (directly) and remotely via the cloud, to resize and edit pictures, and much more. Tablets have come a long way.

#11 Chucky

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Posted 30 October 2012 - 06:13 AM

Fascinating reading about all the rooting, jail breaking, comment on USB-OTG hosting natively, etc. Jeez....the endeavor of optimizing to your level is a hobby in itself! I'm glad folks like you are on the cutting edge of what these new tablet marvels can do. Allows many to reach higher levels of capability. For me at least, I'll be sticking to the more basics....hoping astro programs I purchase will work seamlessly with my tablet without having to rack my brain too much. But again, you did a great job with your Nexus 7. I'm very impressed with your knowledge and willingness to share and challenge others. People like you help us all in that maybe manufactures will enhance their products in ways they never thought about previously.

#12 Spaced

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Posted 30 October 2012 - 03:12 PM

Thanks for the description, Darrell. I envy your confidence in diddling with those gadgets' innards.

#13 snorkler

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Posted 31 October 2012 - 11:38 AM

Thanks, but you folks give me too much credit. I simply took other people's work and consolidated it into my finished product.

I do have a lot of computer experience - 34 years of it, just none with Android before I bought mine.

#14 snorkler

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Posted 31 October 2012 - 03:36 PM

Since I meant for this to be a useful reference thread on what's possible for Android, I'll explain the Directory Bind app, which is available on the XDA Developers Forum. This app let me move my large backup, astronomy and birding data directories to my flash drive, keeping my N7's storage space available. I understated my backup directory size. It's grown to nine backups and 8gb! now. I keep two backups on my N7, which use 2.8gb of my 5.92gb of storage.

Directory Bind isn't an intuitive app to use, but I think anyone can eventually figure it out. You, the user, have to identify the locations of the largest data directories to bind. I used SD Card Storage Optimizer to find those files and directories. On the good side, if I want to bind the following directories:
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/files/
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/files/skydata/
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/files/skyimages/

I only need to bind the trunk directory, and all the upper branches get bound
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/
to a similar directory on my usbdrive
/mnt/sdcard/usbstorage/sda1/Android/data/com.southernstars.skysafari_pro/

The directorybind app developer mounted his external drive at /sdcard/external_sd/ but I used Stickmount's default location, /mnt/sdcard/usbstorage/sda1/, which is where it mounts my USB flash drive's first partition.

I copied all the files from
/mnt/sdcard/Android/data/com.southernstars.skysafari_pro/
to my flash drive's first partition
/mnt/sdcard/usbstorage/sda1/Android/data/com.southernstars.skysafari_pro/,
deleted the original data tree above the trunk, bound the empty trunk directory as the source directory, and the flash drive tree as the target directory(ies).

It worked like a charm. In the capture below, S=source (data) directory, and T=target directorsy. The target is the (now virtual) location where the app is looking to find its data. The source is the actual location where those data are stored.

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Finally, I grabbed a screen capture of SSP's object search screen without my mods shown above, so you can see what it looks like on an unmodified system. No wonder most of you try to operate your touch screen tablets through two layers of red plastic!

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#15 JAT Observatory

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Posted 02 November 2012 - 02:31 PM

I finally rooted my Nexus7 & my Galaxy Nexus. The main reason I did it was so I could use a USB flash drive. What also works is USB mice,keyboards etc. Even my USB to RS-232 adapter works.

I really do like the tablet the laptop sits idle most of the time now. My only complaint is I can't print to my local network printer.

#16 _Z_

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Posted 03 November 2012 - 07:36 AM

You don't need to root the nexus 7 for USB on to the go, there is at least 1 app that can do it.
https://play.google....xususb.importer

#17 JAT Observatory

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Posted 03 November 2012 - 06:40 PM

The problem (for me) is that software is read only.

#18 Ctwo

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Posted 03 November 2012 - 06:57 PM

New N7 (and first tablet) owner here. I was looking for a good astronomy app, this is far beyond my experience, so just looking for a good (the best) astro app for finding object in the night sky - I'm thinking of stellarium on N7 - i.e. just as good and free.

#19 tezster

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Posted 03 November 2012 - 09:15 PM

I just got a N7 and Bluetooth DSC (BETI) this week. For my purposes, I find that screendim along with sky safari's night/red mode sufficiently dark, although it is annoying the home buttons maintain their brightness.

A wireless DSC paired with a tablet is awesome, BTW.

#20 Digital Don

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Posted 03 November 2012 - 09:35 PM

I just purchased a Nexus 7. My main reason for doing so was that I was so impressed with SkySafari I recently installed on my Android phone, I couldn't wait to see it on a larger screen!

SkySafari is an amazing piece of software and I highly recommend it!

Don:usa:

#21 snorkler

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Posted 04 November 2012 - 02:37 AM

Marcus, your printer manufacturer may have a printing app, if you have a wireless printer. If not, you can print to your printer via the cloud from your Nexus 7.

Zeldaboy, no. An unrooted Nexus 7 can only read from an attached usb flash drive. It cannot write to it, nor can it bind directories until it's rooted.

There's a new 2.53 Paranoid Android out as of 11/2/12. Unfortunately, it's just as buggy as 2.52,and crashes in the same manner. I'm unable to set the nav bar color. Needless to say, I'm back running on 2.50 again.

#22 snorkler

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Posted 04 November 2012 - 05:09 PM

Yesterday, Paranoid Android v. 2.531 was released. It's getting good reviews, but still fails to allow me to make changes to the navigation bar colors on my Nexus 7. Ergo, I'm still running PA v. 2.50.

#23 snorkler

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Posted 06 November 2012 - 11:17 AM

Two more versions of Paranoid Android came out 11/3 and 11/4. 2.531 crashed upon leaving the Settings menu. 2.532 successfully changes the navigation bar colors and saves them, but doesn't load them on a reboot or cold boot.

#24 snorkler

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Posted 06 November 2012 - 07:34 PM

Sorry, I missed Ctwo's query on free astronomy apps, and I have no experience with any other Android astronomy apps. But I chose Sky Safari Pro based on recommendations from other threads in this forum. I think there's an Android v. Apple thread that discusses several Android astronomy apps, or there may be an Android apps thread.

Looking on Google Play, and listing the apps I remember other CN users using Google Sky Map, SkEye, Mobile Observatory ($3.99), and the basic Sky Safari ($2.99) and Sky Safari Plus ($14.99).

A search for astronomy app map brings up a few more possibilities, Droid Sky View, Deep Sky Calculator ($1.39), Star Odyssey, Sky Map Assistant ($1.29), Star Chart ($2.99), and AcruSky for Android.

#25 Jon Isaacs

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Posted 07 November 2012 - 08:20 AM

Darrell:

I am curious about the size of the Nexus 7. I have an 8 inch tablet that I use with Sky Safari but it's too big to shirt pocket handy so most of the time I end up using my cell phone with strong reading glasses to magnify the small screen.

A friend just got a Samsung Galaxy Note 2 with it's 5.5 inch screen, it looks like a reasonable choice, small enough to easily fit in a pocket, small enough to be a phone and yet the large screen makes it better suited for apps like Sky Safari...

Size wise, where does the Nexus 7 tablet fit, can you just keep with you in a pocket or something is it necessary to put it somewhere when you are not using it?

Thanks

Jon






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