Gary Servin / ros_lib_melodic

ROS Serial library for Mbed platforms for ROS Melodic Morenia. Check http://wiki.ros.org/rosserial_mbed/ for more information.

Dependencies:   BufferedSerial

Dependents:   rosserial_mbed_hello_world_publisher_melodic Motortest Nucleo_vr_servo_project NucleoFM ... more

ROSSerial_mbed for Melodic Distribution

The Robot Operating System (ROS) is a flexible framework for writing robot software. It is a collection of tools, libraries, and conventions that aim to simplify the task of creating complex and robust robot behavior across a wide variety of robotic platforms.

The rosserial_mbed package allows to write ROS nodes on any mbed enabled devices and have them connected to a running ROS system on your computer using the serial port.

Hello World (example publisher)

Import programrosserial_mbed_hello_world_publisher_melodic

rosserial_mbed Hello World example for Melodic Morenia distribution

Last commit 08 Nov 2019 by Gary Servin

Running the Code

Now, launch the roscore in a new terminal window:

Quote:

$ roscore

Next, run the rosserial client application that forwards your MBED messages to the rest of ROS. Make sure to use the correct serial port:

Quote:

$ rosrun rosserial_python serial_node.py /dev/ttyACM0

Finally, watch the greetings come in from your MBED by launching a new terminal window and entering :

Quote:

$ rostopic echo chatter

See Also

More examples

Blink

/*
 * rosserial Subscriber Example
 * Blinks an LED on callback
 */
#include "mbed.h"
#include <ros.h>
#include <std_msgs/Empty.h>

ros::NodeHandle nh;
DigitalOut myled(LED1);

void messageCb(const std_msgs::Empty& toggle_msg){
    myled = !myled;   // blink the led
}

ros::Subscriber<std_msgs::Empty> sub("toggle_led", &messageCb);

int main() {
    nh.initNode();
    nh.subscribe(sub);

    while (1) {
        nh.spinOnce();
        wait_ms(1);
    }
}

Push

/*
 * Button Example for Rosserial
 */

#include "mbed.h"
#include <ros.h>
#include <std_msgs/Bool.h>

PinName button = p20;

ros::NodeHandle nh;

std_msgs::Bool pushed_msg;
ros::Publisher pub_button("pushed", &pushed_msg);

DigitalIn button_pin(button);
DigitalOut led_pin(LED1);

bool last_reading;
long last_debounce_time=0;
long debounce_delay=50;
bool published = true;

Timer t;
int main() {
    t.start();
    nh.initNode();
    nh.advertise(pub_button);

    //Enable the pullup resistor on the button
    button_pin.mode(PullUp);

    //The button is a normally button
    last_reading = ! button_pin;

    while (1) {
        bool reading = ! button_pin;

        if (last_reading!= reading) {
            last_debounce_time = t.read_ms();
            published = false;
        }

        //if the button value has not changed for the debounce delay, we know its stable
        if ( !published && (t.read_ms() - last_debounce_time)  > debounce_delay) {
            led_pin = reading;
            pushed_msg.data = reading;
            pub_button.publish(&pushed_msg);
            published = true;
        }

        last_reading = reading;

        nh.spinOnce();
    }
}

sensor_msgs/ChannelFloat32.h

Committer:
Gary Servin
Date:
2019-11-08
Revision:
1:da82487f547e
Parent:
0:04ac6be8229a

File content as of revision 1:da82487f547e:

#ifndef _ROS_sensor_msgs_ChannelFloat32_h
#define _ROS_sensor_msgs_ChannelFloat32_h

#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include "ros/msg.h"

namespace sensor_msgs
{

  class ChannelFloat32 : public ros::Msg
  {
    public:
      typedef const char* _name_type;
      _name_type name;
      uint32_t values_length;
      typedef float _values_type;
      _values_type st_values;
      _values_type * values;

    ChannelFloat32():
      name(""),
      values_length(0), values(NULL)
    {
    }

    virtual int serialize(unsigned char *outbuffer) const
    {
      int offset = 0;
      uint32_t length_name = strlen(this->name);
      varToArr(outbuffer + offset, length_name);
      offset += 4;
      memcpy(outbuffer + offset, this->name, length_name);
      offset += length_name;
      *(outbuffer + offset + 0) = (this->values_length >> (8 * 0)) & 0xFF;
      *(outbuffer + offset + 1) = (this->values_length >> (8 * 1)) & 0xFF;
      *(outbuffer + offset + 2) = (this->values_length >> (8 * 2)) & 0xFF;
      *(outbuffer + offset + 3) = (this->values_length >> (8 * 3)) & 0xFF;
      offset += sizeof(this->values_length);
      for( uint32_t i = 0; i < values_length; i++){
      union {
        float real;
        uint32_t base;
      } u_valuesi;
      u_valuesi.real = this->values[i];
      *(outbuffer + offset + 0) = (u_valuesi.base >> (8 * 0)) & 0xFF;
      *(outbuffer + offset + 1) = (u_valuesi.base >> (8 * 1)) & 0xFF;
      *(outbuffer + offset + 2) = (u_valuesi.base >> (8 * 2)) & 0xFF;
      *(outbuffer + offset + 3) = (u_valuesi.base >> (8 * 3)) & 0xFF;
      offset += sizeof(this->values[i]);
      }
      return offset;
    }

    virtual int deserialize(unsigned char *inbuffer)
    {
      int offset = 0;
      uint32_t length_name;
      arrToVar(length_name, (inbuffer + offset));
      offset += 4;
      for(unsigned int k= offset; k< offset+length_name; ++k){
          inbuffer[k-1]=inbuffer[k];
      }
      inbuffer[offset+length_name-1]=0;
      this->name = (char *)(inbuffer + offset-1);
      offset += length_name;
      uint32_t values_lengthT = ((uint32_t) (*(inbuffer + offset))); 
      values_lengthT |= ((uint32_t) (*(inbuffer + offset + 1))) << (8 * 1); 
      values_lengthT |= ((uint32_t) (*(inbuffer + offset + 2))) << (8 * 2); 
      values_lengthT |= ((uint32_t) (*(inbuffer + offset + 3))) << (8 * 3); 
      offset += sizeof(this->values_length);
      if(values_lengthT > values_length)
        this->values = (float*)realloc(this->values, values_lengthT * sizeof(float));
      values_length = values_lengthT;
      for( uint32_t i = 0; i < values_length; i++){
      union {
        float real;
        uint32_t base;
      } u_st_values;
      u_st_values.base = 0;
      u_st_values.base |= ((uint32_t) (*(inbuffer + offset + 0))) << (8 * 0);
      u_st_values.base |= ((uint32_t) (*(inbuffer + offset + 1))) << (8 * 1);
      u_st_values.base |= ((uint32_t) (*(inbuffer + offset + 2))) << (8 * 2);
      u_st_values.base |= ((uint32_t) (*(inbuffer + offset + 3))) << (8 * 3);
      this->st_values = u_st_values.real;
      offset += sizeof(this->st_values);
        memcpy( &(this->values[i]), &(this->st_values), sizeof(float));
      }
     return offset;
    }

    const char * getType(){ return "sensor_msgs/ChannelFloat32"; };
    const char * getMD5(){ return "3d40139cdd33dfedcb71ffeeeb42ae7f"; };

  };

}
#endif