I just find my HAL_UART_Transmit() function cost 15ms. why does it cost so much time?The UART speed is 19200, and I use GPIO set and reset function to check the time cost.Total data length of send buffer is 29 bytes. and I use a 15ms polling loop to ...

I am trying to use the SPI example code, and I configured SPI1 on the NUCLEO-F401RE board in full Duplex work mode.I connected two NUCLEO-F401RE boards together by GND, CLK, MOSI, MISO,and CS(but I use NSS_Soft mode).Because there is no example code ...

I used the sample code of "en.stm32cubef4-v1-28-0\STM32Cube_FW_F4_V1.28.0\Projects\STM32F401RE-Nucleo\Examples\UART\UART_Printf"I just printed the "test" in the while(1) loop. but the display of my computer is werid, and I checked the clock and hal l...