STM32L0xxx firmware update over LPUART1 Pins

[Nikunj Patel]

Dear Team,

We design a board in which one host controller si driving the STM controller over LPuart1 whose pins are as below.

Part Number: STM32L073

PC4 - LPUART1_TX

PC5 - LPUART1_RX

Now, We want to update the firmware of STM using the host controller on these two pins which we normally do over USART1 and USART2.

Please help us to this what we need to change the existing boot loader.

Thanks & Best Regards,

Nikunj Patel

[Peter BENSCH]

The AN2606 lists all possible combinations of usable interfaces for the respective derivative. However, LPUART is not supported by any integrated bootloader of any STM32 yet. The only possibility for a firmware update is therefore to write a bootloader yourself, which is located in the user flash and thus takes away part of it.

Regards

/Peter

[Nikunj Patel]

Dear Peter,

The only possibility for a firmware update is therefore to write a bootloader yourself, which is located in the user flash and thus takes away part of it.

Can you please elaborate more?

Thanks & Best Regards,

Nikunj Patel

[Peter BENSCH]

With your own boot loader, you can use any interface of the particular STM32 for a firmware update.

The bootloader is typically located at the beginning of the flash block instead of the actual user program and decides after the reset whether a firmware update should be made or whether the user program should be jumped to. This actual user program is then located behind the boot loader.

To prevent the boot loader from being accidentally deleted, its flash area can be protected accordingly.

An example of such a boot loader can be X-CUBE-IAP-USART, whose function is described in detail in AN4657.

Regards

/Peter