STM32F4 Bootloader pins connection problem (AN2606)?

mudrovc2 · ‎2013-09-24

Posted on September 24, 2013 at 09:34

Hello.

I'm using STM32F405RG. In my application we plan to use bootloader on USART1 for firmware programming. In AN2606 page 74 is written, that the rest of bootloader channels (USART3, CAN and OTG) inputs must be put in definitive state. But how to do this for USB DM, DP pins?

I cannot connect PA10/PA11 with pull ups or pull downs, because this is now allowed by the USB specification. I need USB connection, but I want to use USART1 bootloader.

What is the solution in this case?

Tesla DeLorean · ‎2013-09-24

Posted on September 24, 2013 at 18:21

I've had to use USART3 on the STM32F4-Discovery because of pin usage issues and attach capacitance.

The key for the boot loader is that the pins remain static so as not to select the wrong interface.

Not sure you're going to be able to use the boot loader via the USART if you have an active USB connection, in which case BOOT0=H should put you in DfuSe mode.

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