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Beaglebone & EVM kit BOOT configuration

SANGILI KUMAR
Genius 3920 points

Hi        

        EVM kit have the switch to configure BOOT device, which to be read by internal boot ROM. Hence the internal ROM read the boot configuration and switch the booting device according to the boot configurations.

       In Beaglebone there is no boot configuration switch, but internal boot ROM how knows the MLO source is MMC card. because there is no GPIO allotted as SYS_BOOT to tell to ROM the default boot device is MMC, how they handled the boot configuration.

      Can anyone tell how the beaglebone boot from MMC as default and how they hardcoded ?

  • 0
    TI__Genius 10210 points

    I would suggest that you refer the BeagleBone schematics and the relevant section of AM335x TRM to better understand this.

  • 0 in reply to Vishveshwar Bhat
    Genius 3920 points

    Hi Mr.Vishveshwar Bhat 

                              Thanks for your reply.  ya we already checked in both schematic Beaglebone and EVM kit. In EVM kit there are DIP switch. but in Beaglebone all SYS_BOOT pins were grounded.  

                              Dip switch position for SD card in EVM is SW3  ON | ON | ON | OFF | ON ( 11101) . But in Beaglebone all pins were grounded, so how they mapping the boot device with ROM code.?

  • 0 in reply to SANGILI KUMAR
    Intellectual 450 points

    Hi Mr. Sangili Kumar,

    You can read the section: "7.2.1 Boot Pins" of http://beagleboard.org/static/beaglebone/latest/Docs/Hardware/BONE_SRM.pdf.

    Also from the Beaglebone schematics I can find the SYSBOOT switches for BB are:

    SYSBOOT(15:0):0100000000010111

    Also it says The boot order is: 

    MMC....SPI....UART....USB......24MHZ

    Also, if you refer the AM335x TRM for SYSBOOT configuration, you will find for SYSBOOT(4:0): if the value is 10111,

    Then the boot order will be: 

    1) MMC0, 2)  SPI0, 3) UART0, 4) USB0

    Now, in case of AM335xEVM(for MMC boot) is:

    As per switch configuration(ON/OFF): SW4: 10111111 SW3:11101000

    And SYSBOOT becomes: 0100000000010111

    So, here both AM335xEVM and Beaglebone are configured for the same boot mode.

    Hope this helps.

  • 0 in reply to Umakanta Patro
    Genius 3920 points

    Thanks Mr.Umakanta Patro

                    Thanks for your reply, but i'm little confuse please can you make clear  in following issues ?

                     You told the in BB SYSBOOT pins are SYSBOOT(15:0):0100000000010111 .  16 pins are connected with common ground so its be weather 0000000000000000 or 1111111111111111. 

                     I  wanna know how they configured as 0100000000010111 in hardware like ground the particular pin or any other intelligence. because i need to design the schematic for default NAND booting. 

    Thanks

    Sangilikumar M


  • 0 in reply to SANGILI KUMAR
    Intellectual 450 points

    Hi Mr. Sangili Kumar,

    Can you please share with me the snapshot of the schematics, where you are finding that all SYSBOOT pins are connected to common ground?

    The schematics which I am referring (link: http://beagleboard.org/static/beaglebone/latest/Docs/Hardware/BONE_SCH.pdf , page 6) shows each SYSBOOT pin gets connected to either pull up or pull down. So for each pin there is a DNI resistor, which will be open.

    So by following to that schematics, I found: SYSBOOT(15:0):0100000000010111.

    Also, for NAND default boot: you can try for the following configuration options in your new design:

    SYSBOOT(4:0):10010   NAND NANDI2C0 USB0 UART0

    SYSBOOT(4:0):10011   NAND NANDI2C0 MMC0 UART0

    SYSBOOT(4:0):10100   NAND NANDI2C0 SPI0 EMAC1

    Hope, this helps.

  • 0 in reply to Umakanta Patro
    Genius 3920 points

    Thanks Mr.Umakanta Patro

                      Now i understand the SYS_BOOT its not common grounded its connected with 100K resistor then its grounded.

                      Thanks for your help. 

  • 0 in reply to SANGILI KUMAR
    Intellectual 450 points

    Hi,

    If my previous post had answered your question, please click Verify Answer button for the same post.