STM32 Read Protection And Rx-Tx pins

[DCtech]

I've flash protection level-1 on my stm32f429. When I open the flash protection on my mcu and connect the serial prolific to read and send data under UART. My source code couldnt run. But if I remove the serial prolific's from the pins. And reset the device, device can run. What is the reason ?

[Peter BENSCH]

Your description is not really understandable. Would it be possible for you to post a more detailed description?

Regards

/Peter