STM32H755ZI bricks after firmware upload or when firmware upload crashes

[kps98]

Hi all,

We’re a small startup developing a commercial product using an STM32H755ZI, and we’re getting ready to ship. One of the key things we want to bulletproof before launch is firmware recovery for end users, especially in case the firmware upload fails (e.g., they unplug during flashing, or the update crashes). At the moment we erase the flash memory and uploads elf files using dfu utils. It works most of the times but we've noticed that when it fails there is no way of getting the device running again unless st-link is used. Even having a switch for boot pin is not helping.

Here are our questions:

• Is relying on the dfu utils safe and recommended for production units?

• What are the best practices for implementing this kind of user-friendly recovery flow?

• Are there better tools or alternatives to dfu-util for desktop apps?

Any help or advice would be really appreciated. Thanks!

[TDK]

Using the supported STM32CubeProgrammer is probably a better choice. Freeze the product version once you verify correct functionality.

> What are the best practices for implementing this kind of user-friendly recovery flow?

Prior to starting the flash, modify option bytes to always boot into the bootloader. After flashing and verifying new configuration, re-modify option bytes to always boot into the user code.