Manually re-flashing the u-boot

Latest revision as of 11:23, 10 February 2012

This page explains how you can manually re-flash the U-Boot into your Neo1973. It is basically the manual task of what the Devirginator tries to do automatically (but not always works).

[edit] Prerequirements

• Neo1973 device (any device will work)
• Debug Board or other device supported by openocd
• lowlevel_foo.bin for your board (e.g. from buildhost)
• u-boot.bin for your board (e.g. from buildhost)
• OpenOCD
• a host PC system (running Linux is strongly recommended, while other OS's might work, too)

[edit] Steps that you do

[edit] Connections

1. Connect the debug board upstream USB port to your PC
2. Connect the FPC to your debug board
3. Connect the FPC to your Neo1973
4. Put a charged battery into your Neo1973
5. Push the power button of your Neo1973 to swithc it on

[edit] Starting software

1. Start OpenOCD (see detailed instructions on OpenOCD page)
2. telnet to port 4444

[edit] Copy u-boot into RAM and start it

So how can we boot from RAM? We use JTAG / OpenOCD to

• Reset and halt the cpu at PC=0

> reset halt
target halted in ARM state due to debug request, current mode: Supervisor
cpsr: 0x400000d3 pc: 0x00000000
MMU: disabled, D-Cache: disabled, I-Cache: disabled

• Download a small piece of code for low-level SDRAM timing initialization (overwrite 4k SRAM of steppingstone)

> load_binary /space/misc/gta01/u-boot.git/board/neo1973/gta01/lowlevel_foo.bin 0            
downloaded 332 byte in 0s 21899us

• Assert a break point at address 0x33f80000 (which indicates that the low-level code has finished)

> bp 0x33f80000 4 hw
breakpoint added at address 0x33f80000

• Run the code up to the break point

> resume
Target 0 resumed
> Target 0 halted
target halted in ARM state due to breakpoint, current mode: Supervisor
cpsr: 0x600000d3 pc: 0x33f80000
MMU: disabled, D-Cache: disabled, I-Cache: enabled

• Download the U-Boot RAM image to 0x33f80000

> load_binary /space/misc/gta01/u-boot.git/u-boot.bin 0x33f80000
downloaded 135692 byte in 6s 567264us

• Resume processing

> resume
Target 0 resumed

At this point, the display backlight gets bright and we see the following familiar prompt on the serial console:

U-Boot 1.1.6 (Jan 13 2007 - 23:44:23)

DRAM:  128 MB
NAND:  64 MiB
*** Warning - bad CRC or NAND, using default environment

In:    serial
Out:   serial
Err:   serial
Hit any key to stop autoboot:  0 
GTA01Bv2 # 

[edit] copying u-boot into RAM

Now you have the full U-Boot running from RAM, you can use all its drivers and have various options to transfer data into the Neo, such as a new U-Boot image for NAND. You can use

• DFU / dfu-utils directly into the partitions such as U-Boot, kernel, rootfs
• alternative
  • • halt the system from JTAG, and copy data into RAM
    • copy data from microSD using mmcinit/ext2load
  • then resume into U-Boot and use 'nand write.e'

FIXME: I'll finish after lunch