rosserial 接收不到订阅的话题数据

最近在研究智能小车的搭建，ROS主控使用的是RK3399，电机驱动使用的是STM32，
RK3399和STM32使用USB线连接，并使用了rosserial_python进行数据传输，
我使用的是网上最经典最成熟的代码框架，话题订阅的结构如下：

some_other_code;
ros::NodeHandle nh;
some_other_code;
void command_callback( const geometry_msgs::Twist& cmd_msg);
some_other_code;
ros::Subscriber cmd_sub("cmd_vel", &command_callback );
some_other_code;

void command_callback( const geometry_msgs::Twist& cmd_msg)
{
          char buffer[300];
    
        required_linear_vel_x = cmd_msg.linear.x;
        required_linear_vel_y = cmd_msg.linear.y;
        required_angular_vel_z = cmd_msg.angular.z;
    
        previous_command_time = millis();

        sprintf (buffer, "NaclChan -----------------------------");
        nh.loginfo(buffer);    
    
        sprintf (buffer, "NaclChan last cmd %d",previous_command_time);
        nh.loginfo(buffer);        
}

int main(void) 
{
                some_other_code;    
                SystemInit();
        initialise();
                some_other_code;

        nh.initNode();    
        nh.advertise(raw_vel_pub);
                some_other_code;
                nh.subscribe(cmd_sub);
                some_other_code;

        while (!nh.connected())
        {
            nh.spinOnce();
        }

         sprintf (buffer, "NaclChan X5 Connected!");
        nh.loginfo(buffer);     
        
                while(1)
        {
            if ((millis() - previous_control_time) >= (1000 / COMMAND_RATE))
            {
                move_base();
                previous_control_time = millis();        
            }
                    
                        some_other_code;
            nh.spinOnce();
                  }
}

RK3399端运行了roslaunch，发现串口通信已经建立，STM32的话题发布和订阅也都有了信息的输出，如下：

[INFO] [1672405665.904525]: NaclChan ROS Serial Python Node
[INFO] [1672405665.938368]: NaclChan Connecting to /dev/rikibase at 115200 baud
[INFO] [1672405668.156120]: Note: publish buffer size is 1024 bytes
[INFO] [1672405668.158158]: Setup publisher on raw_vel [riki_msgs/Velocities]
[INFO] [1672405668.171965]: Setup publisher on raw_imu [riki_msgs/Imu]
**[INFO] [1672405668.186382]: Setup publisher on battery [riki_msgs/Battery]**
[INFO] [1672405668.203644]: Setup publisher on temperature_humidity [riki_msgs/DHT22]
[INFO] [1672405668.221608]: Setup publisher on sonar [riki_msgs/Sonar]
[INFO] [1672405668.256291]: Note: subscribe buffer size is 1024 bytes
[INFO] [1672405668.260395]: Setup subscriber on pid [riki_msgs/PID]
**[INFO] [1672405668.284116]: Setup subscriber on cmd_vel [geometry_msgs/Twist]**
[INFO] [1672405668.323482]: Setup subscriber on servo [riki_msgs/Servo]
[INFO] [1672405668.328804]: NaclChan X5 Connected!

其中 [riki_msgs/Battery]是STM32发布的话题，RK3399端使用rostopic echo /Battery能够看到发布的数据，证明STM32和RK3399间的物理连接是OK的，串口通信也是OK的。
但现在的问题是，STM32订阅了cmd_vel [geometry_msgs/Twist]，咋的都接不到数据。我在RK3399端运行teleop_twist_keyboard，用键盘输入的方式往cmd_vel中写入数据，或者使用rostopic pub 指令往cmd_vel中写数据，都可以被rostopic echo cmd_vel监测到，但STM32始终没有任何反应，回调函数command_callback()根本就没有运行。

被这个问题卡了好久了，不知道咋继续调查了。希望指点