Posted on October 18, 2012 at 11:01
Hi,
Im using a STM32f405RG and i am trying to get a simple USART example to work.
I load the following code to the mcu:
#include ''stm32f4xx.h''
#include ''stm32f4xx_gpio.h''
#include ''stm32f4xx_usart.h''
#include ''stm32f4xx_rcc.h''
void init_usart(void){
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
/* enable peripheral clock for USART2 */
RCC_APB1PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
/* GPIOA Configuration: USART1 TX on PA9 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect USART1 pins to AF9 */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);
USART_InitStructure.USART_BaudRate = 57600;
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_Tx;
USART_Init(USART1, &USART_InitStructure);
USART_Cmd(USART1, ENABLE); // enable USART2
}
void Delay(__IO uint32_t nCount)
{
while(nCount--)
{
}
}
int main(void){
init_usart();
while(1){
USART_SendData(USART1, 'h');
Delay(0x3FFFFF);
}
}
when
GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);
is executed, the pin goes high, and nothing else happens.. The pin never resets and there is no data transmitted over the usart.
Have anyone seen anything like this before?
EDIT:
If I change the code to work with USART2 everything works.. I wonder if it may have something to do with the
RCC_APB2Periph_USART1.
Im not very familliar with this and how the USART behaves if it's incorrect set. I'm also using CooCox.
/Tom
