8 years ago.

Why does 9600 baud work but not 300 on F401RE

Hi,

new guy here. I've been messing with the board for the whole day and i just can't get it to report to com at 300 baud. i need it for a university project and the baud must be at 300 ( to be compatible with other equipment).

Okay so: I set the APB prescaler to /8 so that i would be able to go to the low low 300, then i configure USART2 to asynchronus, for 300 baud, 8bits with parity then i leave parity to none ( i actually need odd) because if i do 9600 without parity - it works. if i do it with parity it doesn't. stop bits - 1 data direction - receive and trasmit. oversampling - 16

the code it needs to process is really primitive:

 uint8_t data[20]= "Hello World\n\r";
  while (1)
  {
HAL_UART_Transmit(&huart2, data, 20, 100);
  }

this is the code and the results when set to 300 ( tera is also configured for 300) :

i must be missing something basic, anyone have any idea? i've tried on both IAR and Keil.

// Configure PPRE2 to 42MHz to obtain 1200 KBits for EC sensor serial communication
    RCC->CFGR &= ~0x0000E000;  // PPRE2, Bit 15-13
    RCC->CFGR |=  0x00008000;  // PPRE2: PCLK2 = AHB / 2
    wait_ms(100);