Trying to develop a MIDI bootloader

[AUnte]

Hi everyone !

I'm new to the arm-based systems and the stm environment. I'm currently trying to develop a midi bootloader, able to update the firmware via Sysex messages.

I already wrote a midi state machine in order to retrieve the midi messages and parse them. But I'm having a hard time trying to develop the bootloader. I was thinking of checking if a button I clicked when the board is powered up to enter the bootloading mode. After that, wait for a SysexMessage and re-write the flash.

Am I heading towards the right direction? How can I check if the button is clicked when the board is powered up?

 I'm a beginner so, any advice or links are welcome! I am working on a STM32F411VE discovery board by the way! :)

[Tesla DeLorean]

>>How can I check if the button is clicked when the board is powered up?

Your primary option here would be to configure the pin as an input once you get into main(), and read the current pin state. The processor isn't going to latch the value for you. You could code routines living in Reset_Handler to do it earlier.

[AUnte]

Thank you! I was thinking of using the Reset_Handler but i didn't find in which file it was.

Well, the Reset_Handler can be found in the startup_stm32f411xe.s file. Does it mean I have to code it in assembly code ?