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66AK2E05: What is "No Boot Mode" on the EVM and what register bits are manipulated?

Mike McCabe
Prodigy 50 points
Part Number: 66AK2E05

Hello,

I've been trying to boot the 66AK2E05 on a custom board and I'm noticing that a lot of the publicly available boot procedure documentation only pertains to the EVM, which needs to be put into "No Boot Mode" before flashing a boot image to memory.

Here's the document I'm currently looking at for the NAND, SPI NOR and UART examples: Using Arm ROM Bootloader on Keystone II Devices

Looking at this K2E-EVM Schematic, SW1 (which selects the EVM boot mode) is simply connected to a range of MCU input pins.

What is this MCU doing to put the K2E into No Boot Mode? Are changes being made to the K2Es DEVSTAT register (or other registers), if so which ones? 

Regards,

Mike

  • +1
    TI__Mastermind 25535 points

    Hi Mike,

    "No Boot Mode" is also one of the options to simply run some examples directly on the board by connecting via CCS and XDS emulator.

    For example, in the document you specified, https://www.ti.com/lit/an/spracn3/spracn3.pdf

    please refer page no.7, and 8.4.2, section Running I2C EEPROM example in the "No boot mode"

    -------

    To have multiple boot option from different peripherals such as (eth, i2c,nand,spi, uart) boot modes shall be used.

    The BOOTMODE[15:0] pins map to DEVSTAT[16:1] bits of the DEVSTAT register.

    IN EVMs, DIP switches are used on selecting boot modes.

    ---------

    The RBL uses the boot configuration information in DEVSTAT to setup and initialize a boot parameter table that is used to control the boot process. This table is stored in MSMC SRAM. Some information in the table is initialized based on the configuration parameters in DEVSTAT while the remaining information is default values based only on the boot mode. The format of the table varies depending on the boot mode. All start with a few entries that are common to all boot modes. Information about the boot parameter table can be found in the device-specific data manual.-- Data sheet - 9.1.2.4 Boot Parameter Table

    -----

    Mike: What is this MCU doing to put the K2E into No Boot Mode? Are changes being made to the K2Es DEVSTAT register (or other registers), if so which ones? 

    This is an apt question. NO-Boot is for Enabling Emulation/Debug mode. In the data sheet, look into the Emulation feature for No boot mode. In schematics of EVM, look into the Emulation circuit and interface. For NO-boot mode, it is not relevant to DEVSTAT register or other registers. 

    And also sleepmode in Boot mode helps in debug feature. Check in your EVM how the debug feature is designed.

    ------------

    For the time being I do not have the EVM in hand, otherwise, by putting it in "No boot mode", we can check the register set in the Memory browser of CCS and observe the changes in the register values. And we can repeat to different boot modes and observe the changes if any in the DEVSTAT register and the Boot parameter table.

    From the data sheet we can know,

    The BOOTMODE[15:0] pins map to DEVSTAT[16:1] bits of the DEVSTAT register

    9.1.2.4 Boot Parameter Table - Boot mode - Byte offset 4

    Regards

    Shankari