Replicant

h1. GalaxyTab2BootloaderInterface

{{toc}}

h2. Boot log

At boot, when pressing the power button for a short time we get:

<pre>

$ picocom -b 115200 /dev/ttyUSB1 

picocom v3.1

port is        : /dev/ttyUSB1

flowcontrol    : none

baudrate is    : 115200

parity is      : none

databits are   : 8

stopbits are   : 1

escape is      : C-a

local echo is  : no

noinit is      : no

noreset is     : no

hangup is      : no

nolock is      : no

send_cmd is    : sz -vv

receive_cmd is : rz -vv -E

imap is        : 

omap is        : 

emap is        : crcrlf,delbs,

logfile is     : none

initstring     : none

exit_after is  : not set

exit is        : no

Type [C-a] [C-h] to see available commands

Terminal ready

Texas Instruments X-Loader 1.41 (Jun 13 2012 - 22:11:09)

Uboot-loading from Emmc

Starting OS Bootloader from EMMC ...

</pre>

Here the device boots, but if the button isn't pressed long enough it shuts down.

When pressing it for a longer time we get:

<pre>

$ picocom -b 115200 /dev/ttyUSB1 

picocom v3.1

port is        : /dev/ttyUSB1

flowcontrol    : none

baudrate is    : 115200

parity is      : none

databits are   : 8

stopbits are   : 1

escape is      : C-a

local echo is  : no

noinit is      : no

noreset is     : no

hangup is      : no

nolock is      : no

send_cmd is    : sz -vv

receive_cmd is : rz -vv -E

imap is        : 

omap is        : 

emap is        : crcrlf,delbs,

logfile is     : none

initstring     : none

exit_after is  : not set

exit is        : no

Type [C-a] [C-h] to see available commands

Terminal ready

Texas Instruments X-Loader 1.41 (Jun 13 2012 - 22:11:09)

Uboot-loading from Emmc

Starting OS Bootloader from EMMC ...

g_nRebootReason = 0x100000

Kernel  @ 81808000 (4524144 bytes)

Ramdisk @ 82800000 (994957 bytes)

set_lcd_panel_id: panel_adc=805

*** ltn070nl01_power_on ***

lcd_pannel_id=3

AST_POWERON

</pre>

Here @AST_POWERON@ probably means that there is a GPIO that can switch between the OMAP4 UART and the modem UART, and that at some point during the boot it's switched to the modem.

I tried to type AT commands like @AT@ but I got no response. Maybe it's because I use the wrong voltage for the UART. Maybe I need to reset the modem through AT commands.

TODO:

* Measure the UART voltage somehow (output only ones and try to measure it)

* Try to see if it responds to AT reset and verbose commands

h2. Xloader 

Note that there is no u-boot here despite what the print says: the Galaxy Tab 2 use xloader, and the source code of xloader is available for the Galaxy Tab 2, and its prints mention u-boot regardless of the bootloader that it loads.

Unfortunately the xloader it uses is signed, so even if it's license is free software we can't change it.

As users are denied the right to run modified versions, we consider the result nonfree even if the license is free.

See the [[GalaxyTab2AndGalaxyNexusBootloaderFreedom]] page for more technical details on that.