Posted on May 30, 2013 at 07:28Something caught my eye:   ''stm32x device protected''  Could this be the cause of your troubles? The inexpensive ST-LINK/V2 has a nice GUI that can quickly unlock the flash.  Ref https://my.st.com/st-extranet-web-act...

Posted on May 30, 2013 at 07:17Refer to AN2606 which says of the STM32F4:  The HSI clock source is used at startup (interface  detection phase) and when USARTx interfaces are  selected (once CAN or DFU bootloader is selected,  the clock source will ...