USART1 - interrupt problem with STM32F051

[jogerh]

Posted on June 04, 2015 at 17:01

Dear community,

I am trying to initialize the UART of the STM32F051 µC – however receiving of data does not work because the interrupt is not triggered. I recognized only the weak initialization of the UART1 interrupt handler in the startup file so I added myself the required lines. Unfortunately it does not work. I would be very happy if someone could check the following code for mistakes.

 void COM_USART1_Init() { //COM_TypeDef COM, USART_InitTypeDef* USART_InitStruct) GPIO_InitTypeDef  GPIO_InitStructure1;  //GPIO STruct GPIO_InitTypeDef  GPIO_InitStructure2;  //GPIO STruct USART_InitTypeDef USART_InitStructure; //USART Struct NVIC_InitTypeDef NVIC_InitStructure;  //for USART //GPIO for USART   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);  //GPIOA_AHBPeriph_CLOCK  // Configure the GPIO_struct USART Tx as alternate function push-pull   GPIO_InitStructure1.GPIO_Pin = GPIO_Pin_9;   GPIO_InitStructure1.GPIO_Mode = GPIO_Mode_AF;  GPIO_InitStructure1.GPIO_OType = GPIO_OType_PP; //PushPull (Gegentakt)  GPIO_InitStructure1.GPIO_PuPd = GPIO_PuPd_UP; //NO Pull  GPIO_InitStructure1.GPIO_Speed = GPIO_Speed_10MHz; // Configure the GPIO_struct  USART Rx as alternate function push-pull  GPIO_InitStructure2.GPIO_Pin = GPIO_Pin_10; GPIO_InitStructure2.GPIO_Mode = GPIO_Mode_AF;  GPIO_InitStructure2.GPIO_OType = GPIO_OType_PP;  GPIO_InitStructure2.GPIO_PuPd = GPIO_PuPd_UP;  GPIO_InitStructure2.GPIO_Speed = GPIO_Speed_10MHz;     //Init GpioStruct GPIO_Init(GPIOA, &GPIO_InitStructure1); GPIO_Init(GPIOA, &GPIO_InitStructure2); GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_1); //Connect the PINS and USART BUS  GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_1); //NVIC for USART USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); // enable the USART1 receive interrupt USART_ITConfig(USART1, USART_IT_TXE, ENABLE); // enable the USART1 send interrupt   // Enable the USARTx Interrupt   NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;  NVIC_InitStructure.NVIC_IRQChannelPriority = 0;  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;  NVIC_Init(&NVIC_InitStructure);  //USART 1  // USARTx configured as follow:      //  - BaudRate = 115200  9600 baud        //  - Word Length = 8 Bits      //  - One Stop Bit      //  - No parity      //  - Hardware flow control disabled (RTS and CTS signals)      //  - Receive and transmit enabled   RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);  //ENABLE USART3 CLK      USART_InitStructure.USART_BaudRate = 115200;/  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 configuration   USART_Init(USART1, &USART_InitStructure);       // Enable USART  USART_Cmd(USART1, ENABLE);}void USART1_IRQHandler (void) {if (USART_GetITStatus(USART1, USART_IT_RXNE) != RESET) { unsigned char received = USART_ReceiveData(USART1); //Receiver //set DAC }}//STARTUPCODE.sUSART1_IRQHandler PROC                EXPORT  USART1_IRQHandler                [WEAK]                B       .                ENDP   ; EXPORT  USART1_IRQHandler              [WEAK]   ; EXPORT  USART1_IRQHandler              [WEAK]

Thank you very much for reviewing my code.

[Tesla DeLorean]

Posted on June 04, 2015 at 17:17

Look, you're using synchronous logic, you need to ENABLE the clock for it to function. Enable the USART1 clock *BEFORE* you touch anything inside the peripheral.

 RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);  // Do it earlier

If you're using C++ (.CPP) watch for name mangling.

[jogerh]

Posted on June 04, 2015 at 17:59

Thank you for responding…

It sounds very promising however for other processors such as the STM32L100RC it seems to be not relevant since I copied and pasted the UART initialization (and just changed a few lines). Is there a significant difference between both the processor types STM32L100RC and STM32F051 regarding “synchronicity�? ? 

[Tesla DeLorean]

Posted on June 04, 2015 at 18:19

They are all dependent on the correct sequencing of code, you can't just slap-dash the cut-n-paste. You need the right code, in the right order.

void COM_USART1_Init() //COM_TypeDef COM, USART_InitTypeDef* USART_InitStruct)
{
GPIO_InitTypeDef GPIO_InitStructure; //GPIO STruct
USART_InitTypeDef USART_InitStructure; //USART Struct
NVIC_InitTypeDef NVIC_InitStructure; //for USART
//GPIO for USART
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //PushPull (Gegentakt)
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_1); //Connect the PINS and USART BUS
GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_1);
//NVIC for USART
// Enable the USARTx Interrupt
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
// USART1 configured as follow:
// - BaudRate = 115200 baud
// - Word Length = 8 Bits
// - One Stop Bit
// - No parity
// - Hardware flow control disabled (RTS and CTS signals)
// - Receive and transmit enabled
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE); //ENABLE USART1 CLK
USART_InitStructure.USART_BaudRate = 115200;
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 configuration
USART_Init(USART1, &USART_InitStructure);
// Enable USART
USART_Cmd(USART1, ENABLE);
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); // enable the USART1 receive interrupt
// DON'T ENABLE UNLESS YOU HAVE DATA TO SERVICE IT
// USART_ITConfig(USART1, USART_IT_TXE, ENABLE); // enable the USART1 send interrupt
}

[jogerh]

Posted on June 05, 2015 at 08:35

Dear Clive1,

thank you very much - now USART1 is able to receive data while triggering the interrupt.