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

Dependencies:   BufferedSerial

Dependents:   rosserial_mbed_hello_world_publisher rtos_base_control rosserial_mbed_F64MA ROS-RTOS ... more

ROSSerial_mbed for Indigo 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

rosserial_mbed Hello World

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();
    }
}
Revision:
0:fd24f7ca9688
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ros/node_handle.h	Thu Mar 31 14:22:59 2016 +0000
@@ -0,0 +1,543 @@
+/*
+ * Software License Agreement (BSD License)
+ *
+ * Copyright (c) 2011, Willow Garage, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials provided
+ *    with the distribution.
+ *  * Neither the name of Willow Garage, Inc. nor the names of its
+ *    contributors may be used to endorse or promote prducts derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ROS_NODE_HANDLE_H_
+#define ROS_NODE_HANDLE_H_
+
+#include <stdint.h>
+
+#include "std_msgs/Time.h"
+#include "rosserial_msgs/TopicInfo.h"
+#include "rosserial_msgs/Log.h"
+#include "rosserial_msgs/RequestParam.h"
+
+#define SYNC_SECONDS        5
+
+#define MODE_FIRST_FF       0
+/*
+ * The second sync byte is a protocol version. It's value is 0xff for the first
+ * version of the rosserial protocol (used up to hydro), 0xfe for the second version
+ * (introduced in hydro), 0xfd for the next, and so on. Its purpose is to enable
+ * detection of mismatched protocol versions (e.g. hydro rosserial_python with groovy
+ * rosserial_arduino. It must be changed in both this file and in
+ * rosserial_python/src/rosserial_python/SerialClient.py
+ */
+#define MODE_PROTOCOL_VER   1
+#define PROTOCOL_VER1		0xff // through groovy
+#define PROTOCOL_VER2		0xfe // in hydro
+#define PROTOCOL_VER 		PROTOCOL_VER2
+#define MODE_SIZE_L         2
+#define MODE_SIZE_H         3
+#define MODE_SIZE_CHECKSUM  4   // checksum for msg size received from size L and H
+#define MODE_TOPIC_L        5   // waiting for topic id
+#define MODE_TOPIC_H        6
+#define MODE_MESSAGE        7
+#define MODE_MSG_CHECKSUM   8   // checksum for msg and topic id
+
+
+#define MSG_TIMEOUT 20  //20 milliseconds to recieve all of message data
+
+#include "msg.h"
+
+namespace ros {
+
+  class NodeHandleBase_{
+    public:
+      virtual int publish(int id, const Msg* msg)=0;
+      virtual int spinOnce()=0;
+      virtual bool connected()=0;
+    };
+}
+
+#include "publisher.h"
+#include "subscriber.h"
+#include "service_server.h"
+#include "service_client.h"
+
+namespace ros {
+
+  using rosserial_msgs::TopicInfo;
+
+  /* Node Handle */
+  template<class Hardware,
+           int MAX_SUBSCRIBERS=25,
+           int MAX_PUBLISHERS=25,
+           int INPUT_SIZE=512,
+           int OUTPUT_SIZE=512>
+  class NodeHandle_ : public NodeHandleBase_
+  {
+    protected:
+      Hardware hardware_;
+
+      /* time used for syncing */
+      uint32_t rt_time;
+
+      /* used for computing current time */
+      uint32_t sec_offset, nsec_offset;
+
+      uint8_t message_in[INPUT_SIZE];
+      uint8_t message_out[OUTPUT_SIZE];
+
+      Publisher * publishers[MAX_PUBLISHERS];
+      Subscriber_ * subscribers[MAX_SUBSCRIBERS];
+
+      /*
+       * Setup Functions
+       */
+    public:
+      NodeHandle_() : configured_(false) {
+
+        for(unsigned int i=0; i< MAX_PUBLISHERS; i++)
+	   publishers[i] = 0;
+
+        for(unsigned int i=0; i< MAX_SUBSCRIBERS; i++)
+	   subscribers[i] = 0;
+
+        for(unsigned int i=0; i< INPUT_SIZE; i++)
+	   message_in[i] = 0;
+
+        for(unsigned int i=0; i< OUTPUT_SIZE; i++)
+	   message_out[i] = 0;
+
+        req_param_resp.ints_length = 0;
+        req_param_resp.ints = NULL;
+        req_param_resp.floats_length = 0;
+        req_param_resp.floats = NULL;
+        req_param_resp.ints_length = 0;
+        req_param_resp.ints = NULL;
+      }
+
+      Hardware* getHardware(){
+        return &hardware_;
+      }
+
+      /* Start serial, initialize buffers */
+      void initNode(){
+        hardware_.init();
+        mode_ = 0;
+        bytes_ = 0;
+        index_ = 0;
+        topic_ = 0;
+      };
+
+      /* Start a named port, which may be network server IP, initialize buffers */
+      void initNode(char *portName){
+        hardware_.init(portName);
+        mode_ = 0;
+        bytes_ = 0;
+        index_ = 0;
+        topic_ = 0;
+      };
+
+    protected:
+      //State machine variables for spinOnce
+      int mode_;
+      int bytes_;
+      int topic_;
+      int index_;
+      int checksum_;
+
+      bool configured_;
+
+      /* used for syncing the time */
+      uint32_t last_sync_time;
+      uint32_t last_sync_receive_time;
+      uint32_t last_msg_timeout_time;
+
+    public:
+      /* This function goes in your loop() function, it handles
+       *  serial input and callbacks for subscribers.
+       */
+
+
+      virtual int spinOnce(){
+
+        /* restart if timed out */
+        uint32_t c_time = hardware_.time();
+        if( (c_time - last_sync_receive_time) > (SYNC_SECONDS*2200) ){
+            configured_ = false;
+         }
+
+        /* reset if message has timed out */
+        if ( mode_ != MODE_FIRST_FF){
+          if (c_time > last_msg_timeout_time){
+            mode_ = MODE_FIRST_FF;
+          }
+        }
+
+        /* while available buffer, read data */
+        while( true )
+        {
+          int data = hardware_.read();
+          if( data < 0 )
+            break;
+          checksum_ += data;
+          if( mode_ == MODE_MESSAGE ){        /* message data being recieved */
+            message_in[index_++] = data;
+            bytes_--;
+            if(bytes_ == 0)                  /* is message complete? if so, checksum */
+              mode_ = MODE_MSG_CHECKSUM;
+          }else if( mode_ == MODE_FIRST_FF ){
+            if(data == 0xff){
+              mode_++;
+              last_msg_timeout_time = c_time + MSG_TIMEOUT;
+            }
+            else if( hardware_.time() - c_time > (SYNC_SECONDS)){
+              /* We have been stuck in spinOnce too long, return error */
+              configured_=false;
+              return -2;
+            }
+          }else if( mode_ == MODE_PROTOCOL_VER ){
+            if(data == PROTOCOL_VER){
+              mode_++;
+            }else{
+              mode_ = MODE_FIRST_FF;
+              if (configured_ == false)
+                  requestSyncTime(); 	/* send a msg back showing our protocol version */
+            }
+	  }else if( mode_ == MODE_SIZE_L ){   /* bottom half of message size */
+            bytes_ = data;
+            index_ = 0;
+            mode_++;
+            checksum_ = data;               /* first byte for calculating size checksum */
+          }else if( mode_ == MODE_SIZE_H ){   /* top half of message size */
+            bytes_ += data<<8;
+	    mode_++;
+          }else if( mode_ == MODE_SIZE_CHECKSUM ){
+            if( (checksum_%256) == 255)
+	      mode_++;
+	    else
+	      mode_ = MODE_FIRST_FF;          /* Abandon the frame if the msg len is wrong */
+	  }else if( mode_ == MODE_TOPIC_L ){  /* bottom half of topic id */
+            topic_ = data;
+            mode_++;
+            checksum_ = data;               /* first byte included in checksum */
+          }else if( mode_ == MODE_TOPIC_H ){  /* top half of topic id */
+            topic_ += data<<8;
+            mode_ = MODE_MESSAGE;
+            if(bytes_ == 0)
+              mode_ = MODE_MSG_CHECKSUM;
+          }else if( mode_ == MODE_MSG_CHECKSUM ){ /* do checksum */
+            mode_ = MODE_FIRST_FF;
+            if( (checksum_%256) == 255){
+              if(topic_ == TopicInfo::ID_PUBLISHER){
+                requestSyncTime();
+                negotiateTopics();
+                last_sync_time = c_time;
+                last_sync_receive_time = c_time;
+                return -1;
+              }else if(topic_ == TopicInfo::ID_TIME){
+                syncTime(message_in);
+              }else if (topic_ == TopicInfo::ID_PARAMETER_REQUEST){
+                  req_param_resp.deserialize(message_in);
+                  param_recieved= true;
+              }else if(topic_ == TopicInfo::ID_TX_STOP){
+                  configured_ = false;
+              }else{
+                if(subscribers[topic_-100])
+                  subscribers[topic_-100]->callback( message_in );
+              }
+            }
+          }
+        }
+
+        /* occasionally sync time */
+        if( configured_ && ((c_time-last_sync_time) > (SYNC_SECONDS*500) )){
+          requestSyncTime();
+          last_sync_time = c_time;
+        }
+
+        return 0;
+      }
+
+
+      /* Are we connected to the PC? */
+      virtual bool connected() {
+        return configured_;
+      };
+
+      /********************************************************************
+       * Time functions
+       */
+
+      void requestSyncTime()
+      {
+        std_msgs::Time t;
+        publish(TopicInfo::ID_TIME, &t);
+        rt_time = hardware_.time();
+      }
+
+      void syncTime(uint8_t * data)
+      {
+        std_msgs::Time t;
+        uint32_t offset = hardware_.time() - rt_time;
+
+        t.deserialize(data);
+        t.data.sec += offset/1000;
+        t.data.nsec += (offset%1000)*1000000UL;
+
+        this->setNow(t.data);
+        last_sync_receive_time = hardware_.time();
+      }
+
+      Time now()
+      {
+        uint32_t ms = hardware_.time();
+        Time current_time;
+        current_time.sec = ms/1000 + sec_offset;
+        current_time.nsec = (ms%1000)*1000000UL + nsec_offset;
+        normalizeSecNSec(current_time.sec, current_time.nsec);
+        return current_time;
+      }
+
+      void setNow( Time & new_now )
+      {
+        uint32_t ms = hardware_.time();
+        sec_offset = new_now.sec - ms/1000 - 1;
+        nsec_offset = new_now.nsec - (ms%1000)*1000000UL + 1000000000UL;
+        normalizeSecNSec(sec_offset, nsec_offset);
+      }
+
+      /********************************************************************
+       * Topic Management
+       */
+
+      /* Register a new publisher */
+      bool advertise(Publisher & p)
+      {
+        for(int i = 0; i < MAX_PUBLISHERS; i++){
+          if(publishers[i] == 0){ // empty slot
+            publishers[i] = &p;
+            p.id_ = i+100+MAX_SUBSCRIBERS;
+            p.nh_ = this;
+            return true;
+          }
+        }
+        return false;
+      }
+
+      /* Register a new subscriber */
+      template<typename MsgT>
+      bool subscribe(Subscriber< MsgT> & s){
+        for(int i = 0; i < MAX_SUBSCRIBERS; i++){
+          if(subscribers[i] == 0){ // empty slot
+            subscribers[i] = (Subscriber_*) &s;
+            s.id_ = i+100;
+            return true;
+          }
+        }
+        return false;
+      }
+
+      /* Register a new Service Server */
+      template<typename MReq, typename MRes>
+      bool advertiseService(ServiceServer<MReq,MRes>& srv){
+        bool v = advertise(srv.pub);
+        for(int i = 0; i < MAX_SUBSCRIBERS; i++){
+          if(subscribers[i] == 0){ // empty slot
+            subscribers[i] = (Subscriber_*) &srv;
+            srv.id_ = i+100;
+            return v;
+          }
+        }
+        return false;
+      }
+
+      /* Register a new Service Client */
+      template<typename MReq, typename MRes>
+      bool serviceClient(ServiceClient<MReq, MRes>& srv){
+        bool v = advertise(srv.pub);
+        for(int i = 0; i < MAX_SUBSCRIBERS; i++){
+          if(subscribers[i] == 0){ // empty slot
+            subscribers[i] = (Subscriber_*) &srv;
+            srv.id_ = i+100;
+            return v;
+          }
+        }
+        return false;
+      }
+
+      void negotiateTopics()
+      {
+        rosserial_msgs::TopicInfo ti;
+        int i;
+        for(i = 0; i < MAX_PUBLISHERS; i++)
+        {
+          if(publishers[i] != 0) // non-empty slot
+          {
+            ti.topic_id = publishers[i]->id_;
+            ti.topic_name = (char *) publishers[i]->topic_;
+            ti.message_type = (char *) publishers[i]->msg_->getType();
+            ti.md5sum = (char *) publishers[i]->msg_->getMD5();
+            ti.buffer_size = OUTPUT_SIZE;
+            publish( publishers[i]->getEndpointType(), &ti );
+          }
+        }
+        for(i = 0; i < MAX_SUBSCRIBERS; i++)
+        {
+          if(subscribers[i] != 0) // non-empty slot
+          {
+            ti.topic_id = subscribers[i]->id_;
+            ti.topic_name = (char *) subscribers[i]->topic_;
+            ti.message_type = (char *) subscribers[i]->getMsgType();
+            ti.md5sum = (char *) subscribers[i]->getMsgMD5();
+            ti.buffer_size = INPUT_SIZE;
+            publish( subscribers[i]->getEndpointType(), &ti );
+          }
+        }
+        configured_ = true;
+      }
+
+      virtual int publish(int id, const Msg * msg)
+      {
+        if(id >= 100 && !configured_)
+	  return 0;
+
+        /* serialize message */
+        uint16_t l = msg->serialize(message_out+7);
+
+        /* setup the header */
+        message_out[0] = 0xff;
+        message_out[1] = PROTOCOL_VER;
+        message_out[2] = (uint8_t) ((uint16_t)l&255);
+        message_out[3] = (uint8_t) ((uint16_t)l>>8);
+	message_out[4] = 255 - ((message_out[2] + message_out[3])%256);
+        message_out[5] = (uint8_t) ((int16_t)id&255);
+        message_out[6] = (uint8_t) ((int16_t)id>>8);
+
+        /* calculate checksum */
+        int chk = 0;
+        for(int i =5; i<l+7; i++)
+          chk += message_out[i];
+        l += 7;
+        message_out[l++] = 255 - (chk%256);
+
+        if( l <= OUTPUT_SIZE ){
+          hardware_.write(message_out, l);
+          return l;
+        }else{
+          logerror("Message from device dropped: message larger than buffer.");
+          return -1;
+        }
+      }
+
+      /********************************************************************
+       * Logging
+       */
+
+    private:
+      void log(char byte, const char * msg){
+        rosserial_msgs::Log l;
+        l.level= byte;
+        l.msg = (char*)msg;
+        publish(rosserial_msgs::TopicInfo::ID_LOG, &l);
+      }
+
+    public:
+      void logdebug(const char* msg){
+        log(rosserial_msgs::Log::ROSDEBUG, msg);
+      }
+      void loginfo(const char * msg){
+        log(rosserial_msgs::Log::INFO, msg);
+      }
+      void logwarn(const char *msg){
+        log(rosserial_msgs::Log::WARN, msg);
+      }
+      void logerror(const char*msg){
+        log(rosserial_msgs::Log::ERROR, msg);
+      }
+      void logfatal(const char*msg){
+        log(rosserial_msgs::Log::FATAL, msg);
+      }
+
+      /********************************************************************
+       * Parameters
+       */
+
+    private:
+      bool param_recieved;
+      rosserial_msgs::RequestParamResponse req_param_resp;
+
+      bool requestParam(const char * name, int time_out =  1000){
+        param_recieved = false;
+        rosserial_msgs::RequestParamRequest req;
+        req.name  = (char*)name;
+        publish(TopicInfo::ID_PARAMETER_REQUEST, &req);
+        uint16_t end_time = hardware_.time() + time_out;
+        while(!param_recieved ){
+          spinOnce();
+          if (hardware_.time() > end_time) return false;
+        }
+        return true;
+      }
+
+    public:
+      bool getParam(const char* name, int* param, int length =1){
+        if (requestParam(name) ){
+          if (length == req_param_resp.ints_length){
+            //copy it over
+            for(int i=0; i<length; i++)
+              param[i] = req_param_resp.ints[i];
+            return true;
+          }
+        }
+        return false;
+      }
+      bool getParam(const char* name, float* param, int length=1){
+        if (requestParam(name) ){
+          if (length == req_param_resp.floats_length){
+            //copy it over
+            for(int i=0; i<length; i++)
+              param[i] = req_param_resp.floats[i];
+            return true;
+          }
+        }
+        return false;
+      }
+      bool getParam(const char* name, char** param, int length=1){
+        if (requestParam(name) ){
+          if (length == req_param_resp.strings_length){
+            //copy it over
+            for(int i=0; i<length; i++)
+              strcpy(param[i],req_param_resp.strings[i]);
+            return true;
+          }
+        }
+        return false;
+      }
+  };
+
+}
+
+#endif