USART2_IRQHandler firing only once

[ekorre]

Hello,

I fail to understand why I only get USART2_IRQHandler to only fire once. I follow a very simple example. PA2 and PA3 shorted together on a ch32v307 R1 EVK.

#include "ch32v30x_conf.h"
#include "debug.h"
#include <stdio.h>
#include <stdint.h>

void USART2_IRQHandler(void) __attribute__((interrupt("WCH-Interrupt-fast")));
void USART2_IRQHandler(void)
{
	static int cnt = 0;
	printf("%d\r\n", cnt++);
}

void init_uart(void)
{
    GPIO_InitTypeDef  GPIO_InitStructure = {0};
    USART_InitTypeDef USART_InitStructure = {0};
    NVIC_InitTypeDef  NVIC_InitStructure = {0};

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2 , ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    /* USART2 TX-->A.2   RX-->A.3 */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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_Tx | USART_Mode_Rx;

    USART_Init(USART2, &USART_InitStructure);
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    USART_Cmd(USART2, ENABLE);
}

int main(void)
{
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    Delay_Init();
    USART_Printf_Init(115200);
    SystemCoreClockUpdate();  
    printf("SystemClk:%d\r\n", SystemCoreClock);
    init_uart();

    while(1) {
        Delay_Ms(1000);
        USART_SendData(USART2, 'x');
        printf("%c\r\n", USART_ReceiveData(USART2));
    };

    return 0;
}

I am getting the following as output. I would expect the counter in the ISR to be printed and incremented, but I only get "0".

SystemClk:144000000
0
x
x
x
...

Any idea where my issue could be? Thanks in advance.

[ekorre]

Solved. It seems that the interrupt routine lacks mret.

See cnlohr/ch32v003fun#90 for details.