STM32F303RBT6; issue with stm32flash communication

JPelt.691 · ‎2019-10-29

Hello,

Im working as a SW Engineer in a project where we have iMX7 and STM32F303RBT6 on our HW.

I'm running Linux SW on iMX7 and my intention is to use stm32flash tool to program SW image from iMX7 into the STM32F303 processor through UART connection.

I have verified that the UART works. I have also connected an STM Nucleo dev.board to my HW and I have been able to communicate to the STM32F072RBT6 on Nucleo board. I have also succeeded to program a binary image into it by using 'stm32flash' tool.

But I have not succeeded in communicating nor programming the STM32F303RBT6 processor that is connected to iMX7. In normal mode both UART signals, RX and TX are HIGH in idle.

But after pulling the BOOT0 pin up by a wire, UART RX is still HIGH but TX is LOW.

This is different behavior compared to what I saw with STM32F072RBT6, in this case RX and TX are HIGH when BOOT0 of the processor is pulled up.

Why is STM32F303RBT6 behaving differently?

Is this the reason why I cannot communicate/program the processor?

What could cause this kind of behavior?

Thanks & best regards,

Jari Peltonen

JPelt.691 · ‎2019-10-31

Hi,

Found the reason for this problem; the UART signals that are used for connecting the processor to iMX7 are using STM pins that are not supported by bootloader.

Bootloader supports USART-1 at pins PA9 and PA10 and USART-2 at pins PA2 and PA3. On my HW the UART is using STM pins PB10 and PB11.

Regards,

Jari