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First Stage User Boot Loader

The first stage user boot loader for the MityDSP-L138 and MityARM-1808 SoMs is based off of version 2.27 of the TI OMAP-L138 Flash and Boot Utilities. The user boot loader requires a couple of small modifications to support the Critical Link SoM, including:

  • Setting the EMIFA clock rate to 100 MHz instead of 25 MHz for FPGA operation.
  • Providing a 312 MHz CPU clock rate (optional) for Profibus support on the Industrial I/O Board.

A tarball of the source code including the modifications made by Critical Link is included in the releases, below.

Releases

2010-05-01 Initial UBL (legacy) Release Notes
2010-05-01 UBLandFLashUtils_2010_10_26.tgz Release Notes
latest The MDK contains the latest UBL in the \sw\3rdparty\ directory MDK-BSP

Boot Usage

The UBL serves two purposes. Primarily, the UBL loads the Second Stage Das U-Boot into DDR2 memory. It also manages setting configurations such as the PLLs, DDR memory settings, and pin multiplexing necessary to load U-Boot. If the UBL gets corrupted or deleted, the board will not boot and it will need to be reflashed following the directions in Reprogramming the Bootloader.

Note: Building/Customizing the UBL is not recommended for most projects, and should not be necessary except in the case where the described settings need to be changed for U-Boot to run normally. Most necessary changes for a custom design should take place in U-Boot or the Linux Kernel.

Building the UBL

The toolchain provided with TI Code Composer Studio is required to build the UBL. The build has been tested with CCSv5.3 on Windows, however v4 and v6 should also work. Download CCS
The TI AIS file format and general bootloader structure used as a basis for these tools can be found in more detail here.

Command line

  1. Download and extract the latest release of the Critical Link UBL from the above table.
  2. Open a command prompt and navigate to the extracted files.
    C:> cd OMAP-L138_FlashAndBootUtils_CriticalLink\OMAP-L138_FlashAndBootUtils_2_27\OMAP-L138\CCS\UBL_ARM\UBL_SPI_MEM\Debug
    
  3. Run gmake to compile the UBL.
    C:> C:\ti\ccsv5\utils\bin\gmake.exe -k clean
    C:> C:\ti\ccsv5\utils\bin\gmake.exe -k pre-build main-build
    

The resulting .ais file will be placed into the UBL_ARM directory.

Code Composer GUI

  1. Download and extract the latest release of the Critical Link UBL from the above table.
  2. Edit the OMAP-L138_FlashAndBootUtils_2_27\OMAP-L138\CCS\UBL_ARM\UBL_SPI_MEM.pjt file to point to the correct path:
    ProjectDir="C:\path\to\project\OMAP-L138_FlashAndBootUtils_2_27\OMAP-L138\CCS\UBL_ARM\" 
    
  3. Import the UBL_SPI_MEM.pjt project into CCS (Project -> Import Legacy CCSv3.3 Project) and Build.

The resulting .ais file will be placed into the UBL_ARM directory.

Reflashing the UBL

See Reprogramming the Bootloader.

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