TMS320F280049C: SCI Bootloader: .TXT file format datasheet

Hi Nibesh,

• The .txt file actually is TI’s standard “boot data stream” (used by all C2000 ROM bootloaders: SCI, SPI, I2C, CAN, Parallel), ASCII-hex-encoded for transmission over SCI. It’s generated from your compiled .out file using the hex2000 utility (bundled with the C2000 compiler / CCS Hex Utility).
  
  
• This is added as a post-build step in CCS (Project Properties > CCS Build > Steps > Post-build steps) for both the flash kernel project (flashapi_ex2_sciKernel) and the application project (flashapi_ex3_liveFirmwareUpdate) , both must be in this SCI8 boot format.
  
  (TI Hex Conversion Utility guide : https://downloads.ti.com/docs/esd/SPRU513J/Content/SPRU513J_HTML/hex_conversion_utility_description.html)
  
  
• This is the actual field layout hex2000 packs into the file, one byte per two ASCII-hex characters:
  
  Section 4.6..8.1 :TMS320F28004x Real-Time Microcontrollers Technical Reference Manual (Rev. H)
  
  There is also a worked example in the TRM ( example 4-1) :
  
• SCI boot mode operation specifics ( TRM Section 4.6.7.2)
  
  • Only accepts an 8-bit stream — key value must be 0x08AA (a 16-bit stream/key 0x10AA is rejected on SCI boot).
  
  • Uses SCI-A autobaud: host sends 'A'/'a', the ROM locks the baud rate against it, then echoes every received byte back to the host so the host can verify each byte landed.
  
  
  
  Default SCI GPIO options for F280049C are mentioned in Section 4.6.9 of the TRM :
  
  
  
  
  
•  Also refer to TMS320F28x Boot Features and Configurations (Rev. A) for boot pin conifg.  F28004x-class devices support fully customizable boot mode selection:
  
  
  •  Up to 3 Boot Mode Select Pins (BMSPs), each mappable to almost any GPIO, configured via the 32-bit BOOTPIN-CONFIG register (Z1/Z2-OTP-BOOTPIN-CONFIG, or EMU-BOOTPIN-CONFIG in RAM for emulation testing).

  • A fully custom boot definition table (BOOTDEF, up to 8 entries) replacing the factory default table, configured via Z1/Z2-OTP-BOOTDEF-LOW/HIGH.

  • We recommend validating your boot config in emulation mode first (writable RAM registers at 0x0D00–0x0D06) since OTP can only be programmed once.

  • Getting Started with Bootloading on C2000 Microcontrollers Section 4.2.2 walks through the exact zero-pin SCI boot emulation sequence: set EMU-BOOTPIN-CONFIG (0xD00) to 0x5AFF FFFF (disables all BMSPs) and EMU-BOOTDEF-LOW (0xD04) to the SCI boot option value (e.g. 0x0001), then reset.

• Flash Kernel flow :
  
  
  1. Device resets into SCI boot mode (BMSPs / BOOTDEF as configured above).

  2. ROM SCI bootloader autobaud-locks and loads flashapi_ex2_sciKernel.txt into RAM (kernel must be built with RAM linker config).

  3. Kernel takes control, erases the target flash sector(s), and connects with the host again over SCI.

  4. Host sends flashapi_ex3_liveFirmwareUpdate.txt (built with Flash linker config) ,same block-size/address/data stream structure  and the kernel’s linked Flash API programs each received block.

  5. Kernel branches to the application’s entry point once the transfer completes (block-size-0x0000 terminator reached).
  
  
  This RAM-kernel-bridges-to-flash pattern is because ROM bootloaders can only ever load into RAM directly flash kernels are the standard bridge 
  
  Reference: Serial Flash Programming of C2000 Microcontrollers App Note (SPRABV4) : https://www.ti.com/lit/an/sprabv4i/sprabv4i.pdf

  
  Other references:
  
  • Live firmware update / bank-swap issue on F280049C (flashapi_ex2 + flashapi_ex3, BANK0/BANK1 swap behavior): https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1383344/tms320f280049c-live-firmware-upgrade-issue

  • SCI kernel autobaud-lock reliability on F280049C: https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1036927/tms320f280049c-ensuring-correct-sci-flash-kernel-loading-to-ram-and-behavior

  • General bootloader .txt file-content question on F280049C: https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1160370/tms320f280049c-bootloader-file-contents

  • SCI serial bootloader best-practice thread (F280049C): https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1399366/tms320f280049c-c2000ware-sci-serial-bootloader-example---best-practice

  • LAUNCHXL-F2800157 CAN flash programming thread (useful cross-reference for the analogous CAN .txt structure): https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1428110/tms320f28388s-customer-bootloader-related-inquiries

  
  
  
  
  
  Regards 
  
  Arpit Varahmihir