LL drivers UART RXNE interrupt not working.

[simo zz]

Hi !

I am writing a code that uses the UART1 and I would like to work on RX interrupt to handle incoming strings.

To start with it, I wrote a code that simply initialise the UART and send a character once the RX Interrupt is fired:

#ifndef HSE_VALUE
#define HSE_VALUE 8000000UL
#endif
 
#ifndef HSI_VALUE
#define HSI_VALUE 16000000UL
#endif
 
#include "stm32f4xx.h"
#include "stm32f4xx_ll_bus.h"
#include "stm32f4xx_ll_rcc.h"
#include "stm32f4xx_ll_usart.h"
#include "stm32f4xx_ll_gpio.h"
#include "stm32f4xx_ll_system.h"
#include "stm32f4xx_ll_pwr.h"
 
void USART1_IRQHandler(void)
{
	if(LL_USART_IsActiveFlag_RXNE(USART1))
		LL_USART_ClearFlag_RXNE(USART1);
 
	if(LL_USART_IsActiveFlag_IDLE(USART1))
		LL_USART_ClearFlag_IDLE(USART1);
 
	LL_USART_TransmitData8(USART1, '!');
}
 
int main(void)
{
        // GPIO AF config
	LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_9 | LL_GPIO_PIN_10, LL_GPIO_MODE_ALTERNATE);
	LL_GPIO_SetPinSpeed(GPIOA, LL_GPIO_PIN_9 | LL_GPIO_PIN_10, LL_GPIO_SPEED_FREQ_VERY_HIGH);
	LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_9, LL_GPIO_AF_7);
	LL_GPIO_SetAFPin_8_15(GPIOA, LL_GPIO_PIN_10, LL_GPIO_AF_7);
 
        // NVIC config
        NVIC_SetPriority(USART1_IRQn, 0x0);
	NVIC_EnableIRQ(USART1_IRQn);
 
        // UART config
       	LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_USART1);
 	LL_USART_Disable(USART1);
 
    const uint32_t pclk = __LL_RCC_CALC_PCLK2_FREQ(SystemCoreClock, LL_RCC_GetAPB2Prescaler());
 
	LL_USART_SetBaudRate(USART1, pclk, LL_USART_OVERSAMPLING_16, 115200);
	LL_USART_SetDataWidth(USART1, LL_USART_DATAWIDTH_8B);
	LL_USART_SetStopBitsLength(USART1, LL_USART_STOPBITS_1);
	LL_USART_SetParity(USART1, LL_USART_PARITY_NONE);
	LL_USART_SetTransferDirection(USART1, LL_USART_DIRECTION_TX_RX);
	LL_USART_SetHWFlowCtrl(USART1, LL_USART_HWCONTROL_NONE);
	LL_USART_SetOverSampling(USART1, LL_USART_OVERSAMPLING_16);
	LL_USART_DisableSCLKOutput(USART1);
	LL_USART_Enable(USARTx);
        LL_USART_EnableIT_RXNE(USART1);
 
        while(1)
	{
		//LL_USART_TransmitData8(USART1, 'x');
		;
	}
}

The code for the UART initialization seems correct because I can send the '*' character in the infinite loop, but I can't send nothing from the USART1_IRQHandler ISR...

What am I missing for the interrupt initialization ?

Thanks.

s.