结合cubemx，用串口中断使stm32f411在接收到不同信息时执行不同的操作，无需dma传输，请给我keil代码

好的，下面是一个简单的示例代码，用于演示如何使用串口中断进行不同操作：

#include "stm32f4xx.h"
#include <string.h>

#define RX_BUF_SIZE 32
#define LED_PIN GPIO_Pin_13

volatile char rx_buf[RX_BUF_SIZE];
volatile uint8_t rx_index = 0;

void USART2_IRQHandler(void) {
    if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET) {
        char data = USART_ReceiveData(USART2);
        if (data == '\r' || rx_index >= RX_BUF_SIZE - 1) {
            // execute command
            rx_buf[rx_index] = '\0';
            if (strcmp(rx_buf, "ON") == 0) {
                GPIO_WriteBit(GPIOA, LED_PIN, Bit_SET);
            } else if (strcmp(rx_buf, "OFF") == 0) {
                GPIO_WriteBit(GPIOA, LED_PIN, Bit_RESET);
            }
            rx_index = 0;
        } else {
            rx_buf[rx_index++] = data;
        }
    }
}

int main(void) {
    // 初始化GPIO和USART2
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    GPIO_InitStructure.GPIO_Pin = LED_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);

    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);

    // 启用USART2接收中断
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
    NVIC_EnableIRQ(USART2_IRQn);

    // 启动USART2
    USART_Cmd(USART2, ENABLE);

    while (1) {
        // do nothing
    }
}

这个示例代码使用了USART2作为串口，并开启了接收中断。当接收到的数据中包含回车符（`\r`）时，就执行相应的操作。在本例中，当接收到“ON”时，点亮LED；当接收到“OFF”时，关闭LED。你可以将这些代码放在CubeMX生成的代码中，然后编译并烧录到你的STM32F411芯片中。