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Boot using USB for starterware

Shradhanand Mahendraker
Intellectual 580 points

Hi, 

I have a doubt regarding performing a boot using USB. the queries i have is that 

a) does usb boot mean bootloader will be copied from PC (via usb interface) to internal ram of sitara and then bootloader will copy application from NOR flash/NAND flash to external ram (DDR)?

or 

b) bootloader and also application will be copied from PC. i.e initially bootloader will be copied from PC to internal ram of sitara and then bootloader will load the application from PC to DDR.

Regards,

Shradhanand

  • 0
    TI__Intellectual 1640 points

    Hi Shradhanand,

    USB boot or any ROM based boot for sitara device series is designed to transfer a bootloader to the internal SRAM . This bootloader will then copy the application image from whatever source you choose.




  • 0 in reply to Shradhanand Mahendraker
    Intellectual 580 points

    Hi Vineet,

    Could you please tell how does my device recognize my boot image (secondary bootloader) which is available on my PC's hard disk. do i need to put the image into any folder? does TI provide any utilities to create some identification for boot rom to recognize it?

    Regards,

    Shradhanand

  • 0 in reply to Shradhanand Mahendraker
    TI__Intellectual 1640 points

    Hi Shradhanand,

    USB boot on AM3xx series uses the RNDIS protocol to emulate a network port/adapter using  USB as data transport layer. In simpler terms, on the PC the AM33xx board comes up as an RNDIS device and then uses the TFTP protocol to transfer an image/SBL from PC to AM3xx device.

    So you need 2 things to be running on the PC, a BOOTP server( to allocate addresses) and a TFTP server to transfer the image. As a response to the BOOTP request from the AM33xx device, the BOOTP server running on the PC would send out the boot image name and this file name would be requested by the AM33xx device to begin the TFTP transfer.

    All that sounds a bit complicated but the bottom line is  you need to run something like TFTPD32 ( downloadable) on your host PC , configure it , set your sysboot pins and you are good to go. Let me look around for some documentation regarding the same.

    Also do note that there were some issues in revision 1.0 of AM33xx and RNDIS boot failed to work. These issue were fixed in a later Silicon revision 2.0. Hope you are using the latter.