Posted on September 30, 2015 at 13:35The project might have been more enlightening, but never mind..
This is on what board using what chip?
Does the HSE_VALUE define match the clock frequency used in your design, and is the setting of the PLL clocks in system_stm32f4xx.c reflective of the board/chip used?
Remember the STM32F4-DISCO board uses an 8 MHz clock source, the examples and template in many of the projects assume the use of an EVAL series board with a 25 MHz clock.
If there is still doubt, have the code output a stream of 'U' characters, and look at the waveform with a scope, and measure the bit timings, and confirm it matches the selected baud rate.
Consider also what you're attaching the serial port too, an RS232 port does not have levels that are compatible directly with the CMOS ones on the STM32, you'd need a MAX3232 type level converter.
