SBL SD

Introduction

If the appimage files are found at the location, the SBL reads the files into a buffer, parses it. Each core is then initialized, RPRC image is loaded, entry points are set and the core is released from reset. For more on bootflow/bootloaders, please refer Understanding the bootflow and bootloaders

This bootloader does SOC initializations and attempts to boot R5 image by the name “app_{corename}”, C7x image by the name “dsp_{corename}”, present in the first FAT partition found in the connected SD card.

The image name for different cores can be as follows

CORE

IMAGE NAME

r5fss0-0

app_r50_0

r5fss0-1

app_r50_1

r5fss1-0

app_r51_0

r5fss1-1

app_r51_1

c75ss0-0

app_dsp0_0

c75ss1-0

app_dsp0_1

The file can be copied to the SD card by connecting it to the host PC using a card reader. Make sure that the images are named without any file extension. If the card is new, make sure that it is formatted with FAT32/16.

SBL reads the CANUART_WAKE_STAT1 MMR in wakeup control MMR to detect partial IO (or IO retention) mode exit. If exit is detected, then SBL will save the wake reason, that is the pad number that triggered the wakeup in BACKUP MMR0 of wakeup control MMR and clear isolation from the pins. Then, it continues the boot.

If a multicore appimage file is found at the location, the SBL reads the file metadata into a buffer, parses it, and identifies the program segments for each core applicable. These program segments are then read from respective offset as per the metadata and loads it to corresponding load address. Each core is then initialized, entry points are set and the core is released from reset.

Since the image is loaded segment wise directly from SD card to load addresses it eliminates the usage of large intermediate scratch buffer to hold the complete image. For more on bootflow/bootloaders, please refer Understanding the bootflow and bootloaders

This bootloader does SOC initializations and attempts to boot a multicore appimage file named “app” present in the first FAT partition found in the connected SD card. The file can be copied to the SD card by connecting it to the host PC using a card reader. Make sure that it is named “app” without any file extension. If the card is new, make sure that it is formatted with FAT32/16.

If a multicore appimage file is found at the location, the SBL reads the file into a buffer, parses it, splits it into RPRCs for each core applicable. Each core is then initialized, RPRC image is loaded, entry points are set and the core is released from reset. For more on bootflow/bootloaders, please refer Understanding the bootflow and bootloaders

Parameter

Value

CPU + OS

wkup-r5fss0-0 freertos

Toolchain

ti-arm-clang

Boards

am275x-evm

Example folder

examples/drivers/boot/sbl_sd

Steps to Run the Example

Since this is a bootloader, the example will be run every time you boot an application using this example. It is run from an SD card unlike other examples which are usually loaded with CCS. Nevertheless, you can build this example like you do for the others using makefile or build it via CCS by importing as a project.

  • When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).

  • When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)

  • Refer to the page Basic steps to flash files to flash this bootloader along with the application to boot.

See Also

BOOTLOADER

Sample Output

[KPI] SYSFW Load                       :      17632us
[KPI] System_init                      :      12246us
[KPI] Drivers_open                     :      82499us
[KPI] Board_driversOpen                :          0us
[KPI] File read from SD card           :       6843us
[KPI] CPU load                         :       9501us
[KPI] SBL Total Time Taken             :     129399us

Image loading done, switching to application ...