Choosing an Android Tablet for the DRO Application

Wednesday, January 9, 2013


When I started the Android Digital Readout project my only tablet was a rooted B&N Nook Color. At that time it was one of the few tablets that could be had for under $300, but it came with a few limitations. First of all, it required rooting to be usable, which voided the warranty etc. Second, the Bluetooth was included “by accident”. While Bluetooth was a part of the wireless chip, the feature was not fully implemented on the hardware level, and was lacking an antenna. This reduced the range to a few feet at most. Finally, even the custom ROMs only went up to Android v2.3 [Gingerbread]. There is nothing inherently wrong with this particular version, but Honeycomb (3.0) and Ice Cream Sandwich (4.0) have much better tablet support.

Please note that there is a Cyanogenmod 9 ROM for Nook. In my experience, while Cyanogenmod 7 has been pretty stable as of late (that's what's installed on the Nook now), CM9 is still largely work in progress. Although it's theoretically possible to get Ice Cream Sandwich on the Nook, it wouldn't be a viable option.

I hesitated to move up to Honeycomb, since Gingerbread still has almost double the market share of ICE (little over 50% vs. approx. 25% for ICE). After a few weeks of “soul searching” I've decided to go for it. The new APIs are much nicer than what is available in 2.x. Since I have precious little time to work on the project, my time will be better spent on the DRO features rather than reinventing the wheels that will become obsolete in a year or two. Even though this means that the DRO won't run on an old cell phone/Nook/Kindle Fire, in the long run the tradeoffs are worth it (at least in my opinion).
With that in mind, here are the hardware requirements for the DRO as it stands right now:

Must Have Features

  • Android 3.0 Honeycomb 4.0 Ice Cream Sandwich or newer. The app will run on 3.0, but given the choice, 4.0 is a better option.
    UPDATE Jul 8, 2013: The upcoming version will no longer support since the limited (1.6%) usage of 3.0 does not justify the required compromises
  • Bluetooth. At this point Bluetooth is the only communication method implemented. In the future I am planning to add USB support as well.
  • Touch screen. The UI can theoretically work without a touch screen, but that defeats the whole point of this project.

Nice to Have Features

  • Screen size of 7” or larger. The application will run fine on Android Phones, but the buttons will be very tiny. The larger the screen, the better obviously, but 7” feels reasonably well, even with my “fat fingers”
  • 1024x600 display resolution (WSVGA) or better. Same as the screen size: the app will run on lower resolution screens, but he user experience will be suboptimal.
  • WiFi. This is mostly for future expansions, but I'm planning to add some features that work better with an internet connection.
  • SD or MicroSD card slot. Again, this is mostly for future expansions.


As you might've noticed, I didn't mention anything about the CPU, RAM, Storage etc. As far as the DRO application is concerned, even single-processor tablets with modest RAM are practically super computers. After all we are reading some short strings 10-50 times per second and refreshing a styled text screen. A quick search on Amazon found over a dozed good candidates for around $200 or less. The least expensive tablet that satisfied all of the above (at the time of this posting) can be had for as little $120. Spending a bit more will get you a nice name-brand tablet that can be used for much more than a DRO.

Since I intend to use the tablet as the “garage computer”, my top choices were Google Nexus 7 and Samsung Galaxy Tab 3. 2013 version of Nexus 7 retails for $230; Galaxy Tab 3 and the previous version of Nexus 7 can be had for $170 or so. I use galaxy Tab 2 in the garage and Nexus 7 for testing and development and can't complain about either.






12 comments :

  1. The next version of the application will target Android OS 4.0 and newer. According to the stats I get from the Google's Developer Console Honeycomb accounts for only 1.6% of all installs. On the other hand, the overhead associated with backwards-compatibility is fairly large.
    The current version will still be available for 3.0 but no future updates will work on it.

    Thank you
    Yuriy

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  2. This has been a fun and great project for me so a big thanks for that. I have been able to get this up and running using my HTC phone, however when I try to connect on my Nook HD+, it connects but then disconnects over and over again. Can you point me in a direction to solve this? Thanks, Josh

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    Replies
    1. The app will disconnect if it doesn't see any input for over 2 seconds (normally the controller send each scale's position 20x per second).
      Make sure that you are getting position reading from the interface (using a BT terminal application, etc.)

      Thank you
      Yuriy

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    2. I finally got it to work on my Nook HD only after doing a cyanogen mod. Thanks.

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  3. Hi Yuri,
    Just purchased an Android phone/tablet to use as a display for this project. Runs Android 4.1.1
    When trying to download from Google Play it says device not supported. I got a tablet that meets all the specs above.
    Also found a link on your site to the apk so tried that as well bur got error message "There is a problem parsing the package".
    Any ideas what could be going on here?
    Glenn

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    Replies
    1. Glenn,
      Do you happen to have a link to the tablet you got? I've seen some "Chinese" tablets that advertise Android 4.1.1 but in fact run a heavily skinned 3.0 or so.

      Thank you
      Yuriy

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  4. Yuriy, on further investigation it appears to be Android 4 but running on a 2.6.35 kernel (gingerbread). That would be the problem I imagine.
    Glenn

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    Replies
    1. Glenn,
      This is what I meant by "heavily skinned". So the one you got is basically a Gingerbread tablet with something that looks like Android 4 :(
      Regards
      Yuriy

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  5. Looks like it. Will have to get another device (and get a refund for the one I have). Frustrating as I now have all the other parts required and have begun mounting the DRO's

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  6. Yuriy I purchased a dell venue 7 with blue tooth 4.0 I am having issues getting it to see the linvor modem.(the modem is blinking and I can see data going to it with a scope. do you think the BT 4.0 could be the issue? (I have another modem coming in case the one I have is bad. ) I will try to connect to the modem tonight with my home laptop. thanks for the product and any help.

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    Replies
    1. Does the tablet bind to it and the app can't see it or does the tablet refuse to bind to the modem?

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    2. Hi, I'm having the same problem (this is also mentioned in the beta-group). The external BT module is BT V2.0 and the module in the tablet is V4.0. This mix seems to work with some apps (BT SPP, Bluetooth SPP Pro, Bluetooth SPP Test) and not with others (TouchDRO,Blueterm). The tablet mates fine, but TouchDRO fails to connect to the stack. I dunno if V4.0 in both ends would solve the problem. TouchDRO is such a nice app, so I hope there will be a solution to this soon.
      Thanks!
      /Johan

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