Hi,
I've taken the example project "toggle_with_CircleOS" to do some first steps with my new STM32 Primer. Adding the attached code to initialize the USART2 enables me to send some bytes via pin PA2 which I can see on my Scope.
On 9600 baud I would expect to see a bit-length of 104 µs, but unfortunately every bit is about 80 µs long. What else do I need to do to set the clock/prescaler correctly?
Any comments are welcome. Many thanks in advance...
Regards,
Markus
void InitUSART()
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Enable USART2 clocks */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* Configure USART2 Tx (PA.2) as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure USART2 Rx (PA.3) as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* USART2 configuration ------------------------------------------------------*/
/* USART2 configured as follow:
- BaudRate = 9600 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
- USART Clock disabled
- USART CPOL: Clock is active low
- USART CPHA: Data is captured on the second edge
- USART LastBit: The clock pulse of the last data bit is not output to
the SCLK pin
*/
USART_InitStructure.USART_BaudRate = 9600;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No ;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_InitStructure.USART_Clock = USART_Clock_Disable;
USART_InitStructure.USART_CPOL = USART_CPOL_Low;
USART_InitStructure.USART_CPHA = USART_CPHA_2Edge;
USART_InitStructure.USART_LastBit = USART_LastBit_Disable;
USART_Init(USART2, &USART_InitStructure);
/* Enable the USART2 */
USART_Cmd(USART2, ENABLE);
}
