帮我写出STM32如何数据解包cmd=2&uid=xxxxxxxxxxxxxxxxxxxxxxx&topic=light002&msg=on获得on的程序

以下是一个简单的程序示例，用于解包从串口接收到的数据，并处理命令为“2”的情况，其中包含UID、主题和消息。

需要注意的是，这只是一个示例程序，实际应用中需要根据具体情况进行修改和优化。

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

#define BUF_SIZE 128

char rx_buffer[BUF_SIZE];
uint8_t rx_index = 0;

void USART2_IRQHandler(void)
{
    if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)
    {
        char data = USART_ReceiveData(USART2);
        if (data == '\n')
        {
            rx_buffer[rx_index] = '\0'; // 添加字符串结束符
            if (strncmp(rx_buffer, "cmd=2&", 6) == 0)
            {
                char *uid_start = strstr(rx_buffer, "&uid=") + 5;
                char *uid_end = strstr(uid_start, "&");
                char uid[32];
                strncpy(uid, uid_start, uid_end - uid_start);
                uid[uid_end - uid_start] = '\0';

                char *topic_start = strstr(rx_buffer, "&topic=") + 7;
                char *topic_end = strstr(topic_start, "&");
                char topic[32];
                strncpy(topic, topic_start, topic_end - topic_start);
                topic[topic_end - topic_start] = '\0';

                char *msg_start = strstr(rx_buffer, "&msg=") + 5;
                char msg[16];
                strcpy(msg, msg_start);

                if (strcmp(msg, "on") == 0)
                {
                    // 执行打开操作
                }
                else if (strcmp(msg, "off") == 0)
                {
                    // 执行关闭操作
                }
            }
            rx_index = 0;
        }
        else
        {
            rx_buffer[rx_index++] = data;
            if (rx_index >= BUF_SIZE)
            {
                rx_index = 0;
            }
        }
    }
}

int main(void)
{
    // 初始化串口和中断
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    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_Init(USART2, &USART_InitStructure);
    USART_Cmd(USART2, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    while (1)
    {
        // 程序主循环
    }
}