STM32F769 ST Bootloader

[YDann.7]

Dear,

I have an issue about the embedded ST bootloader on the STM32F769. I'm not able to communicate with it.

On a custom board, I use a STM32F769BG connected to the USART 1 (PA9 / PA10). When I send the 0x7F value, I don't have a response from the MCU. The startup step is follow :

1. low state on the RST pin and BOOT 0 pin (MCU in reset state)
2. high state on BOOT 0 pin
3. wait 5 ms for pin state stabilization
4. high state on RST pin
5. wait 5 ms for pin state stabilization
6. sending 0x7F value

I also try with the STM32F7 discovery (https://www.st.com/en/evaluation-tools/32f769idiscovery.html) but I have the same issue. On this board, I have unsolder the resistors between the MCU and the embedded ST-Link because it's the USART 1 which is used to do it.

I'm sure that it's not my custom application which is launch when I release the RST pin, because I did a led blinker firmware and when I did the previous step to entre the MCU into the ST bootloader, the led don't blink.

I already used this step to update other MCU (STM32F030RC and STM32F072C8) and it working well.

Maybe I missing something or doing something wrong ?

[Tesla DeLorean]

What other pins might have signals the Loader might interpret​ as connectivity?

A GPS receiver that starts chirping from startup?

Check app note AN2606​ for pin list

[YDann.7]

I know what you mean but we don't have 'intelligent' component which can send data by itself.

There are a lot of peripheral which can be used with the embedded bootloader and we cannot reserved this pins to be sure they will don't disturb the bootloader. The user firmware need this this pins.

I had check this pins and I don't see something which can be wrong.

I also checked the options bytes configuration and it seems good for the 2 boards.

 

I did a test with the Flash Loader Demonstrator from ST (with empty MCU FLASH or not) and I have the same issue, no response from the target, the bootloader cannot be started.