AM263P4: how to build a proper boot flow from external memory

Hi Jan,

As we discussed in the meeting, our boot-flow is pretty similar. 

Jan Bock said:

Our current bootstrap procedure on Cortex-M with external flash is as follows:
– The MCU loads from flash to RAM a minimal L1 boot responsible for initializing the flash driver (e.g., full-speed SPI depending on vendor, encryption, etc.).
– The L1 boot verifies the L2 boot stored in flash (e.g., using a digital signature).
– The L1 boot loads the L2 boot into RAM; the L2 boot manages the targeted OTA link (e.g., UART).
– If no upgrade is required, the L2 boot checks the application image stored in encrypted flash area A (e.g., using a digest and/or digital signature). If the application is valid, it is copied to RAM and/or executed in XIP.
– If an upgrade is required, the L2 boot writes the new application chunks into encrypted flash area B.
– At the end of the upgrade, the L2 boot checks the application image stored in encrypted flash area B (e.g., using a digest and/or digital signature). If the application is valid, it is copied to area A and executed.

You can find details about the boot-flow here: https://dev.ti.com/tirex/explore/node?node=A__ACDKX3HNrOMdwCDY3eQ89A__AM26X-ACADEMY__t0CaxbG__LATEST

All the sample bootloader applications can be found here: https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/EXAMPLES_DRIVERS_SBL.html

Jan Bock said:

If so, could you kindly provide documentation and/or examples for:
– Configuring flash partitioning and encryption
– Managing the boot procedure for a multi-core application

We have specialized FOTA hardware and software driver for handling the updates which can help achieve the customer use-case here. Please find all the details here: 

https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/EXAMPLES_DRIVERS_FOTA_AGENT.html

https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/EXAMPLES_DRIVERS_SWAP_TO_B.html

https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/bootseg_ip_working.html

Multi-core boot procedure is handled automatically through our MCELF image format. For the multi-core applications, a single image is created (called mcelf appimage), which combines different sections of the different cores and boots it. All the tooling and detailed information can be found here: https://software-dl.ti.com/mcu-plus-sdk/esd/AM263PX/latest/exports/docs/api_guide_am263px/MCELF_LANDING.html

We have multi-core boot image support in our bootloaders itself, so it should be easy for customers to generate multi-core boot images and test. The SDK also has sample multi-core applications.

We also have specialized hardware to optimize external flash performance and overcome limitations of external flash architecture (like slow access, security, safety etc) through OptiFlash: https://www.ti.com/lit/an/spradf0a/spradf0a.pdf?ts=1763120039511&ref_url=https%253A%252F%252Fwww.google.com%252F

Let me know if you need more resources or have questions about any of the above.

Regards,
Shaunak