I have a strange situation, code works fine in st link debugger mode. But when i press f8 which means write code to flash, and reset the device - seems like code not running. i use stm32f407 discovery board with st link debugger. what it can be? please help, im out of ideas
On other boards might worry about BOOT0. Chances here is that the board/chip is running, but stuck in a timeout or error loop. Try instrumenting the code so you know how deep it got. Try not using HSE/PLL and just run from 16 MHz HSI which the processor starts with. Loop and Error_Handler() and Hardfault_Handler() routines, output details if you hit either point, or any other while(1) loops you have in your code.