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Booting RTOS on AM1808

John Efstathiades
Prodigy 10 points
Other Parts Discussed in Thread: AM1808

Hello,

I am planning a commercial RTOS port to a custom-designed AM1808 board with an SPI serial NAND flash. One of the things I am trying to understand is what happens when the processor boots and the role of the ROM-based AIS bootloader (described in spraba5.pdf).

To boot the RTOS kernel do I create an AIS image that incorporates the RTOS kernel ELF file and program that into the serial NAND? Can the Windows-based AISgen tool program all types of SPI serial NAND devices?

Do I need to use TIs User Boot Loader (UBL)? Are there any advantages in using this to load my RTOS kernel rather than directly by the ROM bootloader?

During development can I just download the kernel image into RAM via the JTAG interface and run it directly without the ROM bootloader running?

Thanks,

John

  • 0
    TI__Guru 62975 points

    John Efstathiades said:

    To boot the RTOS kernel do I create an AIS image that incorporates the RTOS kernel ELF file and program that into the serial NAND?

    This approach would be ok.

     

    John Efstathiades said:

    Can the Windows-based AISgen tool program all types of SPI serial NAND devices?

    I don't think the AISGen tool has a flash-programming function.  There are AM1808-compatible CCS-based flash utilities included in the Linux SDK (Davinci-PSP) and a UART-based flash utility here: http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility_for_OMAP-L138

    Those utilities are only designed to work with the EVM flash components so if you use a different SPI hookup or different flash configuration you will need to modify the code appropriately.

    John Efstathiades said:

     

    Do I need to use TIs User Boot Loader (UBL)?

    No, the Universal Boot Loader is not required.

    John Efstathiades said:
     

    Are there any advantages in using this to load my RTOS kernel rather than directly by the ROM bootloader?

    This is a matter of preference.  The UBL is written in C so you can modify it to meet your needs if the AISGen functions are limited.

    John Efstathiades said:
     

    During development can I just download the kernel image into RAM via the JTAG interface and run it directly without the ROM bootloader running?

    Yes, this is very common.