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Re: [SLUG] Hacking "Hackable Android Pads"
- To: "David Lyon" <david.lyon.preisshare@xxxxxxxxx>, slug-bounces@xxxxxxxxxxx, "SLUG" <slug@xxxxxxxxxxx>
- Subject: Re: [SLUG] Hacking "Hackable Android Pads"
- From: "Christopher Barnes" <chris.p.barnes@xxxxxxxxx>
- Date: Fri, 17 Feb 2012 09:28:59 +0000
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I don't really know too much about ARM based devices and dev boards but from what I've seen most of them have the same basic features - at least 1 serial port, Card reader, eeprom flashed with boot-loader, and the ARM processor in an SOC (System On Chip) configuration.
If you are lucky the system board will have the serial port brought out to a header or Vias that you can attach the wires to.
In my case there were vias but they weren't labelled. I found a web article a guy wrote who had a similar netbook and who had determined which vias were tx, rx, ground.
If your unlucky in that the serial port HASN'T been brought out onto the system board you'll have to get the datasheet for the proc and identify the serial pins that way.
A PC serial port (RS232) can run voltages anywhere from 10volts to 50volts from what I remember which is why we use the RS232 to lvTTL converter.
LvTTL is low voltage (3.3volt) Transisitor to Transistor Logic.
I've got some schematics to make such a converter - pretty basic, couple of caps, couple of transistors, couple of resistors.
But I'd recommend buying one of the nokia sync cables because you can be fairly certain its going to work.
The last one I bought was about $5 with free shipping. An ebay search for "Nokia CA-42" should give you a few local options.
As for butchering it, I've got a link somewhere. ill dig it up and send to you. Its really easy.
One question I've got, can you see any obvious ways to open the tablet?
A guy I work with bought a cheap one off ebay, couldn't workout how to open it without destroying it.
And another question, what do you want to hack it to do?
The only thing I don't like about these devices is you can't really just run the netinstall of debian, or you can't run a stock standard linux kernel because of device drivers and other board specific stuff.
You need to use kernel compiled for the board which peeves me off because I still haven't found any up to date kernels, and the kernels lack things I'd really like - like the prerequisites for IPSec VPN, more supported filesystems, etc
I was able to get my hands on the manufacturers source thanks to GPL obligations but I'm a total amature at taking someone elses device driver source and integrating it into a recent kernel source.
Anyway, really interested to see how you go hacking it.
One word of advice, if you get on to the console, take a full backup before you start changing anything. Just dump the raw data via tftp somewhere safe so you can dump it back on to the tab if you mess up.
If the previous owner of my netbook had done that it probably would have saved me about 2 solid months of searching for compatible boot loaders and android images.
Sent from my BlackBerry
From: David Lyon <david.lyon.preisshare@xxxxxxxxx>
Date: Fri, 17 Feb 2012 17:42:05
Subject: Re: [SLUG] Hacking "Hackable Android Pads"
That's very interesting information. Perhaps because I half understand
what you're talking about.
I bought an ARM development board and it exposes the exact same
serial console on boot. So many the Arm boards work like this?
So I would be looking for two pins on the processor ?
I'm up to speed with running a 5v serial line. But aren't those processors
a bit lower? as in 2.7v or something?
Thanks for the leads. Fantastic.
On Fri, Feb 17, 2012 at 2:45 PM, Christopher Barnes <
> I don't know about these tablet devices but I once had to "hack" a little
> android netbook because it had been bricked.
> If the tabs are anything like this netbook then its generally not too hard.
> This netbook was an ARM based system with about 128meg ram and 2gig
> onboard Nand flash for storage.
> In a nut shell I had to get a RS232 to lvTTL converter - FT232 chips do
> this or there's old nokia USB sync cables you can butcher.
> Had to find the serial port pin-out on the system board and solder the
> serial converter wires onto it.
> That gave me access to the netbooks serial console.
> I was then able to get access to the boot loader on the device (uBoot).
> From there I could manipulate boot settings, i could boot from SD card,
> boot from TFTP, copy a new kernel into the onboard flash, change the boot
> splash, etc.
> Finding good working android images was the hard part because the
> manufacturer didn't publish any android images so I had to rely on images
> people had dumped from their devices.
> And due to significant hardware differences they didn't really work well -
> no sound, or no mouse, or no wifi, etc.
> In the end I dumped Debian on it and used an android kernel to boot it.
> ------Original Message------
> From: David Lyon
> Sender: slug-bounces@xxxxxxxxxxx
> To: SLUG
> Subject: [SLUG] Hacking "Hackable Android Pads"
> Sent: Feb 17, 2012 2:02 PM
> There's lots of inexpensive Android Tablets. Junk? perhaps:
> - http://www.aliexpress.com/wholesale?SearchText=android+tablet&catId=0
> Question is, how to hack these things?
> They have a linux bootloader, where's information on that generally ?
> I know you have to build a kernel. That means picking devices on the board.
> How's this all done ? Any good sources for Linux Kernels? Whats a good
> Pad to use as a base?
> SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/
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> Sent from my BlackBerry
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