STM32L072CZ. A built-in ST bootloader doesn't run if called from the application.

[GEORGE SANDLER]

I am trying to employ the ST bootloader to upgrade firmware over UART. Problem is, the bootloader refuse to run when called from the application. Based on a debugger log it returns after doing some condition check. I don't know ARM commands to tell what is wrong, and the bootloader source code isn't available.

[Tesla DeLorean]

Probably checking if a valid application, you might have to pick an alternate entry point.

[GEORGE SANDLER]

There is no alternative entry as far as I know.

[GEORGE SANDLER]

There is no alternative entry as far as I know.

[Jr Santos]

Hi George

I'm trying to implement the same as you using the same chip, but I'm facing the same issue.

Were you able to solve this problem?

[GEORGE SANDLER]

There is no solution for the dual-bank flash micro according to ST bootloader team.

[Jr Santos]

Do you know the exact reason for that?

[GEORGE SANDLER]

See the ST full response:

ST Support posted on Jan 3, 2019, 12:11:43 PM

Hi STM32L072 has dual bank boot mechanism. and it is NOT possible to jump to Bootloader on any device having dual bank boot mechanism or flash empty check mechanism. Because the Bootloader will consider this attempt as hw request to execute dual boot or empty check and will simply jump to user flash. If you want to bypass this mechanism, there are two options: - Use option Bytes / Boot pins to configure boot from Bootloader then reset - Jump to Bootloader but ensure that the first word in the user flash (@0x0800 0000) is erased (ie. write zeros to it). Best regards, MCU-Tech-Support Please visit ST Customer Support Portal for further information https://my.st.com/ols#/ols/editrequest/00070461 --------------- Original Message --------------- From: OLS Service Email To Case [online.support@st.com] Sent: 12/28/2018 12:08 AM To: glsandler@hotmail.com Subject: STM32L072CZ. A built-in ST bootloader doesn't run if called from the application [ ref:_00Db0YtG6._5000X1aDd2F:ref ] Hi, I'm working with bootloader team to understand the issue. I'll update you as soon as I get an update. Thank you, MCU-Tech-Support. Please visit ST Customer Support Portal for further information https://my.st.com/ols#/ols/editrequest/00070461 ref:_00Db0YtG6._5000X1aDd2F:ref

[Jr Santos]

Thank you.

Did you try to implement some of the two options that they explained?