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();
    }
}

Diff: sensor_msgs/CompressedImage.h

Revision:
0:04ac6be8229a
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sensor_msgs/CompressedImage.h	Fri Nov 08 14:38:09 2019 -0300
@@ -0,0 +1,88 @@
+#ifndef _ROS_sensor_msgs_CompressedImage_h
+#define _ROS_sensor_msgs_CompressedImage_h
+
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include "ros/msg.h"
+#include "std_msgs/Header.h"
+
+namespace sensor_msgs
+{
+
+  class CompressedImage : public ros::Msg
+  {
+    public:
+      typedef std_msgs::Header _header_type;
+      _header_type header;
+      typedef const char* _format_type;
+      _format_type format;
+      uint32_t data_length;
+      typedef uint8_t _data_type;
+      _data_type st_data;
+      _data_type * data;
+
+    CompressedImage():
+      header(),
+      format(""),
+      data_length(0), data(NULL)
+    {
+    }
+
+    virtual int serialize(unsigned char *outbuffer) const
+    {
+      int offset = 0;
+      offset += this->header.serialize(outbuffer + offset);
+      uint32_t length_format = strlen(this->format);
+      varToArr(outbuffer + offset, length_format);
+      offset += 4;
+      memcpy(outbuffer + offset, this->format, length_format);
+      offset += length_format;
+      *(outbuffer + offset + 0) = (this->data_length >> (8 * 0)) & 0xFF;
+      *(outbuffer + offset + 1) = (this->data_length >> (8 * 1)) & 0xFF;
+      *(outbuffer + offset + 2) = (this->data_length >> (8 * 2)) & 0xFF;
+      *(outbuffer + offset + 3) = (this->data_length >> (8 * 3)) & 0xFF;
+      offset += sizeof(this->data_length);
+      for( uint32_t i = 0; i < data_length; i++){
+      *(outbuffer + offset + 0) = (this->data[i] >> (8 * 0)) & 0xFF;
+      offset += sizeof(this->data[i]);
+      }
+      return offset;
+    }
+
+    virtual int deserialize(unsigned char *inbuffer)
+    {
+      int offset = 0;
+      offset += this->header.deserialize(inbuffer + offset);
+      uint32_t length_format;
+      arrToVar(length_format, (inbuffer + offset));
+      offset += 4;
+      for(unsigned int k= offset; k< offset+length_format; ++k){
+          inbuffer[k-1]=inbuffer[k];
+      }
+      inbuffer[offset+length_format-1]=0;
+      this->format = (char *)(inbuffer + offset-1);
+      offset += length_format;
+      uint32_t data_lengthT = ((uint32_t) (*(inbuffer + offset))); 
+      data_lengthT |= ((uint32_t) (*(inbuffer + offset + 1))) << (8 * 1); 
+      data_lengthT |= ((uint32_t) (*(inbuffer + offset + 2))) << (8 * 2); 
+      data_lengthT |= ((uint32_t) (*(inbuffer + offset + 3))) << (8 * 3); 
+      offset += sizeof(this->data_length);
+      if(data_lengthT > data_length)
+        this->data = (uint8_t*)realloc(this->data, data_lengthT * sizeof(uint8_t));
+      data_length = data_lengthT;
+      for( uint32_t i = 0; i < data_length; i++){
+      this->st_data =  ((uint8_t) (*(inbuffer + offset)));
+      offset += sizeof(this->st_data);
+        memcpy( &(this->data[i]), &(this->st_data), sizeof(uint8_t));
+      }
+     return offset;
+    }
+
+    const char * getType(){ return "sensor_msgs/CompressedImage"; };
+    const char * getMD5(){ return "8f7a12909da2c9d3332d540a0977563f"; };
+
+  };
+
+}
+#endif