17' tablet (OPi normal)

gaara

Hi all!

Here is my project: build a 17.1' tablet with Android system and Orange Pi model 1, normal (A20 SoC)

I already have the screen (from and old laptop): Philips LP171WP4

So, to build it, I want a touch screen, wifi, and others...
The material:
- touch sreen (usbtouchscreen driver) -> OK
- 42000 mAh @ 5V power bank -> OK, 4h15 autonomy with the screen. Now, I want to have a jauge in Android!
- Android 4.2 or better (this source do not active the wifi, but touch driver can be compiled) -> OK
- The case: Difficult question, but I think make it with resin and glass cloth. It's lightweight and strong !  Other solution: 3D printing.

And maybe later other gadgets if my budget allows me:
GPS, Bluetooth, Accelerometer, etc..

For this moment I make trys with Orange Pi, but if all works I will make it with Orange Pi Plus.
Here is a pic of my project at this time (05/2015):
-Pro: -touchscreen ok
        - android ok, with all the apps
        - sata ssd 64gb ok  but now I use a 64Gb fast SD, it's more power-economic      - gps ok (see here)     
-Cons: - sound, need a DAC (2x2W)
           - start-up some times impossible, need to remove/replug the sd card          - can't use GPIO, no app for Android exist          - accelerometer too hard to install / work.

Website of the project: http://www.diskiopi.com/

KingNyx

Wait, are you putting an OTG over top of the laptop screen?

gaara

What you mean by OTG ?

RaveenBouy

How's the Progress, Gaara? :V

gaara

Well... Not so bad !
The screen and the touchscreen are ok, both works with Android. It's a resistive touchscreen, so no multitouch !
However, it doesn't matter. I havn't tested XBMC yet, but mali driver is here.


Now, the big question will be: how to power all of this? 0.93A is with 12V, but the card can be powered with 5V (maybe 3 or 4A)
So I will to study about battteries now...
edit: the pic is awful, sorry

KingNyx

You will want something similar to this. http://www.aliexpress.com/store/ ... 1777_519758791.html

Then the 5v will power the pi and the 12v will power the screen. Might want a couple in parallel for extra run time.

gaara

It's a good idea, thanks. But unfortunately I would like a slimest battery as possible, like 10 or 15mm maximum.
The screen can be powered with 5v (5~24v), so I think a 7.2V battery can be used for all the system. (with the maximum capacity)

For the board, I think I will hack it, like this: http://misapuntesde.com/post.php?id=432
All things I don't need will be removed, and other components (audio jack, I/O button..) will be moved !

I would like also to boot Android from SATA/SSD, but I havn't tried yet to see how I can do.

KingNyx

I think youll find that a screen that big will suck a lot of juice. Also the lower the voltage the higher the amperage needed to power it. Since 7.2v is the low end of its 5-24v. Meaning unless you run several batteries in parallel OR sacrifice thickness, youll be losing run time.

http://www.alibaba.com/product-d ... for_1938394219.html

This is slightly thick, but you can open it up and take the battery out. Plus you'll gain the circuitry for recharging it.  

gaara

yes, because the safely charge is also a big question

gaara

Some news!
I have done some try with a battery I have purchased 4 years ago, it's a Tekkeon MP3450.
This battery can be set with 7.5V, 9V, 12V, 14V and 19V. The capacity is 50Wh, so about 4500 mAh@12V.
I have tried the screen alone, without Pi for the moment. The display is just the desktop of android, not a movie (XBMC works!! )
The results are:

Voltage	consumption of the screen (A)	duration
7.5V	xx (don't work)	xx
9V	0.90	35 min
12V	0.85	15 min
14V	0.80	7 min, but the luminosity is better than 9V
19V	0.68	don't try

      table
                                      
So, you're right KingNyx, it's short !!
But this battery is just 4500 mAh, so with 20000 mAh it should work about 2h, and 3h with 30000mAh, if my calculation is true.
I have found this, the higher capacity I have found for a slim battery: http://www.alibaba.com/product-detail/China-Factory-Universal-Powerbank-30000mAh_1454289280.html
or this other one: 20000mAh@14.8V
It includes the charging circuit and it's possible to charge & discharge at the same time.
With this battery, the total thickness of the tablet would be 25 ~ 28 mm, a little thinck... And I don't speak about the weight! But it don't matter.

I will try 9V with the Pi soon, to see how long time it works with the 4500mAh battery. I will have a better idea of the total duration.
Edit: with the Pi, the duration is 20 min@9V. So 2h15 with 30000 mAh battery !