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Runnig code from RAM without accessing flash

Hello,

I have a problem with one very special device based on ARM cortex M3. I need to program the whole flash memory(from begining) and I have to use only UART interface. No other interface can be used... I have to use only three commands(in this UART mode) which can download code direct to RAM on specifying address, start it from specified RAM address and can reset device.

I need to write a bootloader code, which can be downloaded to RAM using mentioned commands by only two communication wires(RxD and TxD UART) - I hope, this will not be an unbeatable problem...

But my problem lies elsewhere. I write bootloader in Keil uVision4, build it and generate hex file. How can I recognize in created hex file executive portion of alone bootloader code? Because I need to download to RAM only these piece of code and run it from RAM.

Do you see other way how testing bootloader code for downloading and starting from RAM? Standard Keil option - download bootloader code to flash, then copy it to RAM and run code from RAM is not possible. I need copy a bootloader code direct to RAM.

I was hoping that somebody would be able to clarify my problem!

Best regards,
Milan Muller