USART not entering ISR STM32F030C8

Question

I'm working on UART using interrupts on Stm32F030 controller. I have done the following init.

void fnUart_Init(void)
{
 USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;

/* USART1 For Debug */
/* Enable GPIO clock */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA , ENABLE);
/* Enable USART clock */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);


/* USART1 Pins configuration */

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_1); 
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_1);    

/* Configure pins as AF pushpull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
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_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);  

/* USARTx configured as follow:
- BaudRate = 115200 baud  
- Word Length = 8 Bits
- Stop Bit = 1 Stop Bit
- Parity = No Parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
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_Init(USART1, &USART_InitStructure);


/* NVIC configuration */
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);


USART_ITConfig(USART1,USART_IT_RXNE,ENABLE); 
/* Enable USART */
USART_Cmd(USART1, ENABLE);
}

UART2 Init

 void fnUart2_Init(void)
{
 USART_InitTypeDef USART_InitStructure;
 NVIC_InitTypeDef NVIC_InitStructure;
 GPIO_InitTypeDef GPIO_InitStructure;

 /* USART1 For Debug */
 /* Enable GPIO clock */
 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA , ENABLE);
/* Enable USART clock */
 RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);


 /* USART1 Pins configuration 
 /* Connect pin to Periph */
 GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_1); 
 GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_1);    

 /* Configure pins as AF pushpull */
 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
 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_NOPULL;
 GPIO_Init(GPIOA, &GPIO_InitStructure);  

 /* USARTx configured as follow:
 -  BaudRate = 115200 baud  
 - Word Length = 8 Bits
 - Stop Bit = 1 Stop Bit
 - Parity = No Parity
 - Hardware flow control disabled (RTS and CTS signals)
 - Receive and transmit enabled
 */
  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_Init(USART2, &USART_InitStructure);

/* NVIC configuration */
NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
 NVIC_Init(&NVIC_InitStructure);

USART_ITConfig(USART2,USART_IT_RXNE,ENABLE); 
/* Enable USART */
USART_Cmd(USART2, ENABLE);
  }

The IrqHandler is as follows

void USART1_IRQHandler(void)
{
  printf("\n\r Inside ISR1");
}

I have the following printf function which prints data on UART2 when printf is called.

#define PUTCHAR_PROTOTYPE int std::fputc(int ch, FILE *f)
PUTCHAR_PROTOTYPE
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */
USART_SendData(USART2, (uint8_t) ch);

/* Loop until transmit data register is empty */
while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET)
{}
return ch;
}

While loop has nothing running in it as of now. Both the UART's are Initialized properly. This is verified by using printf for both UART1 and UART2. Now wrote this minimal code to test the interrupts. I'm sending any data via UART1 via Realterm software and USB-TTL converter and checking on UART2 whether USART1_IRQHandler() is getting called or not. No response.

Also i was reading about the status and the interrupt flags. They are a bit confusing. When to use and clear those flags? But first i'm not getting why the execution is not entering the ISR? Did i miss something in the init? I do not have a debugger with me so using breakpoints and checking the execution is not applicable in my case. My goal is to send data received on UART1 to UART2 and data from UART2 to UART1. I'm using the standard periph libraries and not HAL libraries. Any suggestions?

Answer 1

I am strongly guessing it comes in the USART1_ISR just once,

you need to clear the relevant USART1 pending Receive not empty (RXNE) bit by calling this USART_ClearITPendingBit(USART1, USART_IT_RXNE); inside the ISR.