How can i reset the HDP2EN to 0

[HQIN.1]

Currently, i working on the nucleo-L552zeq and i run the SBSFU exemple propose by the cubeL5. i use the script regression.sh and the script the SBSFU_UPDATE.sh to initialize the board and download the firmware. this example can work normally on the board.

 

Then i reset the board to some Trustzone project without SBSFU. The Trustzone project still work but then i can't use those 2 script to run the SBSFU-TrustZone project because the HDP2EN no egal to 0.

 

I try to modify this option byte directly with STM32cubeProgrammer, it dosen't work. then i search the user manul and know that i need to modify the registe FLASH_SECWM2R2 and FLASH_SECHDPCR to reset the HDP2EN.

I add this 2 line into my TrustZone project and place it in the main.c(GPIO_IOToggle_TrustZone_Secure/Application/User/main.c) but after i lauch the program, the HDP2EN is still egal to 1.

So how can i reset the HDP2EN by setting these 2 registes?

Thanks in advance.

[Bubbles · Accepted solution]

Hello @HQIN.1​ ,

clearing the HDP2EN involves Option byte programming, it's not just simple register operation.

I believe easiest is to use functions from stm32l5xx_hal_flash_ex.c to update the Option Bytes.

Jarda