在stm32中，使用HAL_UARTEx_RxEventCallback接受不定长字符串，当串口接受到“blink”时执行闪烁灯，接收到“flow”时执行流水灯，给出代码示例

在STM32中，使用HAL库的UART接收事件回调函数`HAL_UARTEx_RxEventCallback`来监听特定字符串并相应地控制灯的操作，首先需要安装HAL库并理解基本的串口通信流程。以下是一个简单的示例代码，展示了如何实现这个需求：

#include "stm32f1xx_hal.h"
#include "string.h"

typedef enum {
    ACTION_BLINK,
    ACTION_FLOW,
} Action;

static Action action = ACTION_BLINK;
static uint8_t string_buffer[100];
static volatile bool string_received = false;

// UART HAL Callback function
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
    if (string_received) {
        HAL_UART_Receive_IT(huart, string_buffer, sizeof(string_buffer));
    }
}

// Custom Rx Event Callback
void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, UART_HandleTypeDef__ReceiverInitTypeDef* recv_init_type) {
    if (!string_received && strcmp((char*)recv_init_type->pData, "blink")) {
        return;
    }

    string_received = true;
    if (strcmp((char*)recv_init_type->pData, "blink")) {
        action = ACTION_BLINK;
    } else if (strcmp((char*)recv_init_type->pData, "flow")) {
        action = ACTION_FLOW;
    } else {
        // Reset the buffer and received flag when we find an unknown command
        memset(string_buffer, 0, sizeof(string_buffer));
        string_received = false;
        return;
    }

    // Call your blinking or flow control function here based on the 'action'
    handle_light_action(action);
}

// Function to handle light actions based on the received string
void handle_light_action(Action action) {
    switch (action) {
        case ACTION_BLINK:
            // Implement code for blinking light here
            break;
        case ACTION_FLOW:
            // Implement code for flowing light here
            break;
        default:
            break;
    }
}

int main(void) {
    // Initialize UART and set callbacks
    // ...

    // Enable RX interrupt and start listening
    HAL_UART_Receive_IT(&huart1, string_buffer, sizeof(string_buffer));

    while (1) {
        // Your main loop can continue here without blocking on UART reception
    }
}