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Enable "RS485 mode" while in "bootloader mode"?

Question asked by Brad Grissom on Feb 6, 2015
Latest reply on Feb 13, 2015 by Brad Grissom
Is it possible to enable "RS485 mode" while in "bootloader mode" to allow the possibility to perform a DFU (device firmware update) over RS485?

We use a STM32 F072 microcontroller on our custom PCB board and we have the USART port connected to a RS485 chip (ST1480).

I have not had success in trying this on our board, but I might be missing something.  My attempt involved configuring the USART port in RS485 mode using USART_DECmd() and then jumping to the bootloader via a function pointer (as discussed in other STM32 threads).

I was also wondering if it is possible to use different USART pins than the default when in bootloader mode.  If this were possible, I would think you would need to configure the pins as "Alternate Function X", configure the USART, then jump to the bootloader.

References:

- AN2606 "System Memory Boot Mode" Section 20 - STM32F07xxx (p. 87)
- AN3155 USART protocol for bootloader mode
- RM0091  STM32 Reference manual, Section 26.5.16 - RS232 Hardware flow control and RS485 Driver Enable (p. 699)

Thanks!

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