Flashing SRAM with USART bootloader

[HShal.2]

I followed the article on placing a program into SRAM - I can't place the link here, on an STM32 (I'm using the STM32L476RG Nucleo board)

I can successfully execute the program from SRAM directly from STM32CubeIDE however when I try and load the program into STM32CubeProgrammer and program into SRAM using the UART bootloader, I can see that the device has successfully been connected to however I get this issue:

 13:54:33 : Error: Write address not acknowledged: 0x20000000

 13:54:33 : Error: failed to download Segment[0]

 13:54:33 : Error: failed to download the File

Is it possible to program the SRAM using the UART bootloader?

[Foued_KH]

Hello @Community member​ ,

You can refer to this Application note : Programming an external Flash memory using the UART bootloader built-in STM32 microcontrollers

Also, I recommend you this article : How to use STM32CubeProgrammer to access the USART bootloader on my STM32 board

Hope I helped you!

Foued

[Pavel A.]

Of course you cannot "flash" SRAM because RAM is not flash 🙂

The debugger, however, knows the difference very well.

You can make a custom bootloader (similar to the "in-app programming" examples with ymodem) that loads and executes code in RAM.

Maybe the CubeProgrammer API library allows to make a host app that does the same without a loader on the target. (I haven't studied the API well; the Segger J-Link API certainly allows this).

[HShal.2]

Thanks for the response Pavel! So its not possible to directly program the SRAM using the stock ST bootloader, without writing a custom one?

[Pavel A.]

I'm not saying this is 100% impossible. I just do not know how.