STM32H750 System Memory Bootloader Does Not Respond as App Notes AN2606 and AN3155 Suggests It Should

[EricD]

Hello!

A number of things to digest here:

The STM32 microcontroller system memory bootloader has not been responding correctly to my commands:

According to App note AN3155, I should be able to send a 0x7F to the serial port configured for booting as defined in app note AN2606. The problem is that I get a 0xA0 or other gibberish returned when I send that value out ranging from bauds of 9600 to 115200.

We have a stm32h750 with boot pins configured for USART2 rx and tx mapped to PA3 and PA2.

I realize in App note AN2606 on page 219 it states USART2 does not work for V13.2 but i have no way of identifying what version we are running, as the bootloader does not respond.

I assume my problem may be USART2, but the real question is, have I overlooked something? Also, is there a way to update the system memory bootloader? It would be nice to guarantee a fully working version of the bootloader for production purposes.

I eagerly await your response.

Thanks in advance,

Eric

[Tesla DeLorean]

Pins at CMOS levels, not RS232 compatible.

Even Parity used, ie 9600 8E1

The H7 parts should function materially the same.

The System Loader does not get updated in the field.

The boot loader can be read via SWD/JTAG

[EricD]

Thank you for the prompt response Clive!

Re-reading my question, I realized I left out a lot of information.

>>Pins at CMOS levels, not RS232 compatible.

We have a RS-232 transceiver attached

Also, RS-232 communication works fine in our application on the same pins.

>>Even Parity used, ie 9600 8E1

I double checked our settings and we appear to be configured correctly.

>>The H7 parts should function materially the same.

We started out on the Nucleo-STM32H743ZI where we could successfully communicate with the System Memory Bootloader. I think that this re-enforces that the issue may be as documented on page 219.

>>The System Loader does not get updated in the field.

Well, that's unfortunate.

>>The boot loader can be read via SWD/JTAG

Thats a great idea! I'll try this next.

Thanks for the input,

Eric