stm32f0 discovery usart1 tx stays high

[reetz]

Posted on October 01, 2012 at 09:55

Hello,

I try to use the usart1 pa9 as tx and pa10 as rx with the following code  /* Enable GPIO clock */  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);   //PA9 ,PA10  /* Enable USART clock */  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);  /* Connect PXx to USARTx_Tx */  GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_0);     //PA9 -> TX  /* Connect PXx to USARTx_Rx */  GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_0);    //PA10 -> RX  /* Configure USART Tx as alternate function push-pull */  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);  /* Configure USART Rx as alternate function push-pull */  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;  GPIO_Init(GPIOA, &GPIO_InitStructure);  /* USART configuration */  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_Init(USART1, &USART_InitStructure);  /* Enable USART */  USART_Cmd(USART1, ENABLE); sending when KEY (Pa0) is pressed:  USART_SendData(USART1, (uint8_t) 'F');                   while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);                   while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); All I get is a continuous high on the port, no reaction whatsoever. TIA tom #stm32f0-usart

[Tesla DeLorean]

Posted on October 01, 2012 at 16:04

Looks reasonable enough.

Perhaps have a loop generating constant traffic, see if that works

while(1)
{
while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
USART_SendData(USART1, 0x58);
}

[reetz]

Posted on October 02, 2012 at 06:22

Thanks Clive, that makes it easier to see.

Both versions work now (key and continuous) I elimiated same fiddling with port a which was above the code i posted. Thanks tom