void encode(void)
{
    unsigned char sand_buff[14];
    unsigned long sum;
    float speed;
    float direction;

    sand_buff[0] = sand_buff[1] = 0xaa;//帧头
    sand_buff[13] = sand_buff[14] = 0xbb;//帧尾
    sand_buff[2] = ((unsigned short)speed & 0xff00)>> 8;   //取速度的高八位
    sand_buff[3] = (unsigned short)speed & 0x00ff ;   //取速度的低八位
    sand_buff[4] = (unsigned short)(speed * 100) & 0xff;    //取小数点后两位

    sum=0;
    for(i=2;i<=10;i++)
        sum+=pack_data[i];
        
    sand_buff[11] = (uint8_t)(sum & 0xff);  //取所有数值(除了帧头帧尾)加起来的低八位
}

static unsigned char rev_data[14];//接收数组
void decode(void)
{
    if(rev_data[0] == 0xaa && rev_data[1] == 0xaa && rev_data[12] == 0xbb && rev_data[13] == 0xbb)//检查帧头帧尾
    {
       for(i=2;i<=10;i++)
            sum += rev_data[i];
        if((sum&0xff) != rev_data[11]) return -1; //计算校验和

        float speed = (float)((int16_t)(rev_data[2]<<8 | rev_data[3])) + ((float)(int8_t)rev_data[4]/100);//接收到实时速度

        unsigned char sbus_ch1 = rev_data[7];   //遥控器通道1
        unsigned char sbus_ch1 = rev_data[8];   //遥控器通道2
        unsigned char sbus_ch1 = rev_data[9];   //遥控器通道3
        unsigned char sbus_ch1 = rev_data[10];   //遥控器通道4
    }
}

cp -r code ~/catkin_ws
cd ~/catkin_ws
catkin build

roslaunch driver.launch