Getting access to u-boot

Follow below steps to get access to the bootloader of your device.

Prior to boot-process

• Enter Service Menu ( quickly push [INFO] [MENU] [MUTE] [POWER] on your remote control )
• Change setting for your RS232C interface to "debug" ( Control -> Sub Option -> RS-232 Jack -> [ Debug | UART | Logic ] )
• Change setting for Watchdog to "off", so that the device doesn't reboot while you are in uBoot menu ( Control -> Sub Option -> Watchdog -> [ on | off ] )

Terminal Connection Parameters

• Use following connection parameters with your terminal-client ( e.g. Kermit, Hyper Therminal or ZOC Terminal ):

Baudrate: 115200
Data bits: 8
Parity: none
Stop bits: 1
Flow Control: none

For Older models (like B530), you can try lower baudrates (like 9600 bps)

During the boot-process

• Press and hold "~"
• once you see "Hit any key to stop autoboot: ..." hit ENTER ( by default there is a booting delay of 2 seconds )

Now you should have a boot prompt as show below.

Example output of the bootloader on a UExxB7000

U-Boot 1.1.6 (Dec 12 2008 - 15:55:34)

DRAM:  128 MB
**************** device info  *******************
nPgsPerSLCBlk = 128
nPgsPerMLCBlk = 256
nSctsPerPg = 8
nNumOfUsBlks = 994
OneNAND[booting] mode / clk = S / 50Mhz
*************************************************
TinyBML[0] open success
env_relocate_spec
Success loading partition
Environment Data loading success!!
No ethernet found.
In:    serial
Out:   serial
Err:   serial
Net:   RTL8139#0
Hit any key to stop autoboot:  0

===============================
===============================
     BOOTROM DEBUG SESSION
===============================
1. ENVIRONMENT SETUP 

2. SHOW PARTITION

===============================
0. JUMP TO UBOOT PROMPT
r. REBOOT
===============================
===============================
SELECT COMMAND:

Output from "2. SHOW PARTITION" shows the partitions as listed below:

<< CS0 PARTITION INFORMATION >>
======================================================================================
     description          load addr          id           attr      first_blk  no_blks
======================================================================================
 0 : boot loader          0x60100000     (0x00000000)    SLC (0x9001)   0        1
--------------------------------------------------------------------------------------
 1 : u-boot               0x60200000     (0x00000001)    SLC (0xd401)   1        1
--------------------------------------------------------------------------------------
 2 : u-boot env           0x60300000     (0x00000002)    SLC (0x9001)   2        1
--------------------------------------------------------------------------------------
 3 : update util          0x60400000     (0x00000003)    SLC (0x9001)   3        1
--------------------------------------------------------------------------------------
 4 : kernel image         0x61000000     (0x00000004)    SLC (0xd001)   4        8
--------------------------------------------------------------------------------------
 5 : root file system     0x61400000     (0x00000005)    SLC (0x9001)   12       8
--------------------------------------------------------------------------------------
 6 : boot modules         0x61800000     (0x00000006)    SLC (0x9001)   20       4
--------------------------------------------------------------------------------------
 7 : driver+exeDSP 1      0x70000000     (0x00000007)    MLC (0xa001)   24       60
--------------------------------------------------------------------------------------
 8 : appdata+cmmLib 1     0x78000000     (0x00000008)    MLC (0xa001)   84       45
--------------------------------------------------------------------------------------
 9 : driver+exeDSP 2      0xffffffff     (0x00000009)    MLC (0xa001)   129      60
--------------------------------------------------------------------------------------
10 : appdata+cmmLib 2     0xffffffff     (0x0000000a)    MLC (0xa001)   189      45
--------------------------------------------------------------------------------------
11 : mtd_tlib rw          0xffffffff     (0x00000014)    MLC (0xa101)   234      450
--------------------------------------------------------------------------------------
12 : mtd_rwarea rw        0xffffffff     (0x00000015)    MLC (0x2101)   684      42
--------------------------------------------------------------------------------------
13 : mtd_infolink rw      0xffffffff     (0x00000016)    MLC (0x2101)   726      150
--------------------------------------------------------------------------------------
14 : OTA rw               0xffffffff     (0x00000017)    MLC (0x2101)   876      118
--------------------------------------------------------------------------------------
======================================================================================

<< CS1 PARTITION INFORMATION >>
======================================================================================
Device[1] not opened

Output from "1: ENVIRONMENT SETUP" with very interesting environment variables:

------------------------------
-     ENVIRONMENT SETUP      -
------------------------------
1. BOOTING COMMAND      = bbm load fkernel;go 60008000
2. BOOTING DELAY        = 2
3. TARGET IP            = 10.88.23.246
4. SERVER IP            = 10.88.27.160
5. GATEWAY IP           = 10.88.23.1
6. ETHERNET ADDRESS     = 10:11:12:13:14:15
7. BOOTING ARGS         = root=139:6 rw ethaddr=10:11:12:13:14:15 ip=10.88.23.246 :10.88.27.160:10.88.24.1:255.255.255.0::eth0 console=ttyS1
8. UPDATE BOOTING ARGS
------------------------------
s. SAVE ENVIRONMENT
x. EXIT
------------------------------

The available uBoot commands are shown via "0. JUMP TO UBOOT PROMPT":

LEONID # help
?       - alias for 'help'
mtest   - simple RAM test
autoscr - run script from memory
base    - print or set address offset
bbm   - BBM sub-system
bdinfo  - print Board Info structure
boot    - boot default, i.e., run 'bootcmd'
bootd   - boot default, i.e., run 'bootcmd'
bootm   - boot application image from memory
bootp   - boot image via network using BootP/TFTP protocol
cmp     - memory compare
coninfo - print console devices and information
cp      - memory copy
crc32   - checksum calculation
echo    - echo args to console
fatinfo - print information about filesystem
fatload - load binary file from a dos filesystem
fatls   - list files in a directory (default /)
go      - start application at address 'addr'
help    - print online help
iminfo  - print header information for application image
itest   - return true/false on integer compare
jade     -
loadb   - load binary file over serial line (kermit mode)
loads   - load S-Record file over serial line
loady   - load binary file over serial line (ymodem mode)
loop    - infinite loop on address range
md      - memory display
mm      - memory modify (auto-incrementing)
mtest   - simple RAM test
mw      - memory write (fill)
nfs     - boot image via network using NFS protocol
nm      - memory modify (constant address)
pci     - list and access PCI Configuration Space
ping    - send ICMP ECHO_REQUEST to network host
printenv- print environment variables
rarpboot- boot image via network using RARP/TFTP protocol
reset   - Perform RESET of the CPU
rtl8139_eeprom - read & print out eeprom contents
rtl8139_eth_addr <mac addr> - write new mac address to eeprom.
rtl8139_eth_init - write 0xffff into eeprom
rtl8139_eth_setup - write default values into eeprom
run     - run commands in an environment variable
saveenv - save environment variables to persistent storage
saves   - save S-Record file over serial line
setenv  - set environment variables
sleep   - delay execution for some time
smctest [r|w|t] [addr]- raw access to DATARAM0 1KB(ldm/stm by 8 words)
tftpboot- boot image via network using TFTP protocol
usb     - USB sub-system
usbboot - boot from USB device
version - print monitor version
LEONID # fatls
usage: fatls <interface> <dev[:part]> [directory]
LEONID #boot[/code]

Entering "boot" from uboot menu starts over normally without issues.

Boot TV from USB using u-boot

After you get access to u-boot menu, you can boot external images from USB.
More on Boot_from_USB_using_u-boot

Flash TV partitions from u-boot

Here you can find detailed How-To restore TV from u-boot:
Recovery_of_Bricked_Device

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--Dynamic1969 22:30, 4 December 2009 (UTC)