Custom Bootloader for STM32F3xxx Series

[RChow]

Hi,

Does anyone know if it's possible to replace the default bootloader that ships with the controller with the custom one?

I searched the net, and the answer I get is that it's not possible. I may be wrong.

Also, I could not find the source code for the default serial bootloader. Can someone point me where I can get it from, or if someone has already written one, would appreciate if you can share it.

Best regards,

Rahul

[Tesla DeLorean]

It is in ROM/OTP so you don't get to replace it. If you were shipping several millions worth of parts you might be able to get something custom loaded at the factory.

Source is not provided, several IAP examples are provided in the various libraries.​

[RChow]

Thanks Clive.

So, I can conclude that we have to go with the boot-loader provided by ST and there is no other option.

My requirement is that I want the boot-loader to work on RS485 interface and the default boot-loader will not work.

Regards,

Rahul

[Tesla DeLorean]

Correct the default loader won't be suitable.

You'd need to implement your own loader using the first several sectors in FLASH, this can implement any protocol you wish, and work with the hardware specific to your board implementation.

For production test stage programming I'd recommend exposing PA9, PA10, NRST, BOOT0 at test points on the board, and also SWD/JTAG connections for debugging. These pins should be free of other encumbrances in the design.

Check AN2606 for information about the system loader, and IAP examples for your own loader.

[Pavel A.]

You can make (hardware) adapter from 485 to TTL UART. If some software protocol is involved (like filtering messages by target address, etc) you can put another smaller microcontroller in the middle, such as STM8.

-- pa