STM CircleOS forum / Is it possible to enter hw bootloader after software reset?

iX3 · 2010-04-23 15:39:56

In my application, I would like to be able to use the built-in/ROM bootloader from ST without having physical access to the PCB (e.g. open the box and change jumpers or DIP switches).

What I'm considering is using a flip-flop to enable a transistor to connect a pull-up resistor to the BOOT0 pin. But then I need to reset the flip-flop somehow when the hardware bootloader is finished loading the new code into FLASH. Perhaps I could use the hardware reset signal from the processor to reset the flip-flop? However, if this is the case, then I can't use a hardware reset to start the bootloader. $1 Otherwise perhaps I need to add more complex logic to the design.

What do you recommend?

Also, $1 Table 2 in AN2606 only lists USART1 as a supported serial peripheral. Also in section 2.1 it says

AN2606 :
The bootloader embedded in STM32F10xxx devices uses configuration 1, which means that only the USART1 peripheral is supported.

Last edited by iX3 (2010-04-23 15:48:46)

z4gunn · 2010-08-10 16:11:43

I have the same dilemma of a robust method to enter DFU boot mode from the user flash. I would have to imagine that this topic is frequently encountered with the requirement of easy field upgrades (i.e. no user intervention other than plugging in the USB cord and pressing program from the control application).

Perhaps one method would be to use two 555 timers configured in one-shot mode. An output IO pin (BOOT_EN) from the MCU could trigger the one shot pulses from the 555's. The output of one of the 555 timers would be connected to the input of the BOOT0 pin. The output of the other 555 timer would be connected through an inverter to an AND gate, which would also be connected to the physical reset switch in the system. The AND gate would allow the MCU to be reset by either the or switch or 555. The reason for two 555's is to have different one shot pulse widths. The BOOT0 pulse has to be held high longer than the reset is held low. Of course pull-ups/pull-downs would have to be used to make sure that the 555's are only triggered with the BOOT_EN pin (i.e. triggered from firmware).

Assuming this circuit can boot into DFU, there is still the issue of the reset to boot the newly downloaded firmware. Section 5.5 of AN3156 states that it is possible to leave DFU mode via a DFU_UNLOAD request from the HOST, thus this secondary reset is not required.

Hope this helps.

Last edited by z4gunn (2010-08-10 16:13:19)

# 1 2010-04-23 15:39:56 Is it possible to enter hw bootloader after software reset?

Is it possible to enter hw bootloader after software reset?

AN2606 :

# 2 2010-08-10 16:11:43 Is it possible to enter hw bootloader after software reset?

Re: Is it possible to enter hw bootloader after software reset?

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