usart problem

[pranathi1091]

Posted on December 10, 2012 at 11:23

Hello All,

I am using STm32f2. I am using USART1 , i wnat to read and write some data to the device connected to USART1 I am setting 9600 as baud rate, i could see RXNIE RE,TE ,SBK,WAKE,PS,PEIE,IDLEIE,TCIE bits set in CR1 register and TXe and TC bits set in SR register. But my baud rate reister is always empty. I am unable to write or read from the device Please let me know what could be the problem Here is my code Usartx is USART1 PA9->USART1TX Pa10->USART1RX /**************************************************************************************/ void Uartinit(void) { USART_InitTypeDef *USART_InitStruct; //USART1 Configuration //GPS Baud rate 9600 // NO HardwareFlowControl //No parity // USART_DeInit(USART1); UsartLowlevelinit(); USART_InitStruct->USART_BaudRate=9600; USART_InitStruct->USART_HardwareFlowControl=USART_HardwareFlowControl_None; USART_InitStruct->USART_Mode=USART_Mode_Rx | USART_Mode_Tx; USART_InitStruct->USART_Parity=USART_Parity_No; USART_InitStruct->USART_StopBits=USART_StopBits_1_5; USART_InitStruct->USART_WordLength=USART_WordLength_9b; USART_Init(USART1, USART_InitStruct); USART_ITConfig(USART1 , USART_IT_RXNE, ENABLE); USART_ITConfig(USART1 , USART_IT_TXE, ENABLE); USART_Cmd(USART1, ENABLE); } /**************************************************************************************/ void NVIC_Configuration(void) { NVIC_InitTypeDef NVIC_InitStruct; /* Configure the NVIC Preemption Priority Bits */ NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0); /* Enable the USART1 Interrupt */ NVIC_InitStruct.NVIC_IRQChannel = USART1_IRQn; NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 4; NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0; NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStruct); } /**************************************************************************************/

void UsartLowlevelinit (void)

{ GPIO_InitTypeDef GPIO_InitStructure;

//Peripheral Clock Enable

//Enable GPIO clock RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE);

USARTx_CLK_INIT(USARTx_CLK, ENABLE);

//USART1 GPIO configuration

GPIO_PinAFConfig(USARTx_TX_GPIO_PORT, USARTx_TX_SOURCE, USARTx_TX_AF); GPIO_PinAFConfig(USARTx_RX_GPIO_PORT, USARTx_RX_SOURCE, USARTx_RX_AF); //Configure USART TX pin 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_InitStructure.GPIO_Pin = USARTx_TX_PIN;

GPIO_Init(USARTx_TX_GPIO_PORT, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = USARTx_RX_PIN;

GPIO_Init(USARTx_RX_GPIO_PORT, &GPIO_InitStructure); }

/**************************************************************************************/

uint8_t ReceiveData(uint8_t *Data,uint32_t TimeOut) { uint8_t Counter=0; while((USART_GetITStatus(USARTx, USART_IT_RXNE) != RESET) && (Counter != TimeOut)) { Counter++; }

if(Counter != TimeOut)

{ *Data = (uint8_t)USART_ReceiveData(USARTx); return SUCCESS; } else { return ERROR; } } /**************************************************************************************/ void USART1_IRQHandler(void) { static uint8_t TxIndex = 0; static uint8_t RxIndex = 0; if (USART_GetITStatus(USART1, USART_IT_TXE) != RESET) // Transmit the string in a loop { USART_SendData(USART1, g_ucGpsCommand[TxIndex++]); if (TxIndex>=(sizeof(EVENT_BUFF_SIZE - 1))) TxIndex = 0; } Thanks #stm32-clock

[Tesla DeLorean]

Posted on December 10, 2012 at 15:46

Please let me know what could be the problem

Why 9-bit with 1.5 stop bits? Why enable Interrupts for RX when you don't service it in the interrupt routine. Presumably you have a continuous stream of inbound data, and only periodic command sending. Why does the content of BRR matter? Should you be able to read it? If you have the wrong baud rate (use a scope), it is most likely because there is a discrepancy between HSE crystal value, and the software HSE_VALUE define. You don't provide the defines, make sure you are enabling the right clocks and pins.

[pranathi1091]

Posted on December 11, 2012 at 04:46 Thanks My baud rate issue is solved.I m clear with the clock I am using now Why enable Interrupts for RX when you don't service it in the interrupt routine. I did not get what u meant I have changed my word length to 8 bits with 1 stop bit which actually device requires.Presumably you have a continuous stream of inbound data, and only periodic command sending. Yes i have a stream of data coming in.But m not getting where the commands in my code are periodical Could u pls let me know.