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STM32F303 USART bootloader: NACK for "Go" command?

Question asked by grabner.markus on Jul 7, 2014
Latest reply on Jul 9, 2014 by carmi.gil
Hi!

How can I tell the STM32F303 bootloader to run application code from flash memory? After reading AN3155, I tried the following byte sequence (">" indicating bytes sent to the serial interface, "<" bytes received from the interface):

>: 0x7f (baud rate detection)
<: 0x79 (ACK)
>: 0x21 0xde ("go" command + checksum)
<: 0x79 (ACK)
>: 0x08 0x00 0x00 0x00 0xf7 (address + checksum)
<: 0x1f (NACK)

I don't understand why the "go" command fails to run code at address 0x08000000. Which command should be sent to launch application code? Does anything else need to be setup before executing the "go" command? Does the "go" command only work if flash memory was actually written to in the same bootloader session? I tried at 9.6 kbaud and 100 kbaud and got the same results for both.

Thanks & kind regards,
Markus

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