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rosserial arduino: tf::broadcaster contradicts using publisher

asked 2015-02-02 03:39:20 -0500

flokati gravatar image

Hello together,

I am running rosserial on the arduino UNO with the "rosserial_server" packages node "serial_node" under ubuntu 14.04. The setup works in general, I just can not solve the following problem:

When using a tf::broadcaster and another publisherof arbitrary type at the same time, the arduino must run into some error. At least the serial_node either never gets anything back from the arduino or gives the error output:

[WARN] [WallTime: 1422869167.806875] Serial Port read returned short (expected 1 bytes, received 0 instead). [WARN] [WallTime: 1422869167.807257] Serial Port read failure:

I prepared a minimal example:

#include <ros.h>
#include <std_msgs/Int32.h>
#include <ros/time.h>
#include <tf/tf.h>
#include <math.h>
#include <tf/transform_broadcaster.h>

// Configuration hardware
const long BAUD_RATE = 115200;
int PUBLISH_HZ =10;

//time of last tf send
long int lastSendMillis=0;


//ros variables
const char base_link[] = "/base_link";
const char odom[] = "/odom";
ros::NodeHandle nh;
geometry_msgs::TransformStamped t;
tf::TransformBroadcaster broadcaster;

//std_msgs::Int32 iMsg;
//ros::Publisher intChatter("timeDifs", &iMsg);

void setup()
{
  t.header.frame_id = base_link;
  t.child_frame_id = odom;

  nh.getHardware()->setBaud(BAUD_RATE);
  nh.initNode();

  broadcaster.init(nh);

 // nh.advertise(intChatter);
}

void loop() {

  int timeDiff=(millis() - lastSendMillis);
  if (timeDiff >= 1000/PUBLISH_HZ) {
    // send it now!
    lastSendMillis=millis();

   t.transform.translation.x = 1;
   t.transform.translation.y = 1;
   t.transform.rotation = tf::createQuaternionFromYaw(M_PI / 2.);
   t.header.stamp = nh.now();

   broadcaster.sendTransform(t);

  // iMsg.data=timeDiff;
  // intChatter.publish(&iMsg);

   nh.spinOnce();
  }
}

It is enough to comment in the message definition "std_msgs::Int32 iMsg;" to produce the error. I can not see how this is related.

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answered 2015-04-02 06:22:58 -0500

flokati gravatar image

Turns out this one and several more "random" errors (combinations of unrelated variables and lines of codes would not work together but seperately) was just related to the ros.h taking up a lot of memory.

Hard to guess though, make sure your program is using the right arduino, so for the Arduino UNO use:

#define __AVR_ATmega8__

Have a look at: http://wiki.ros.org/rosserial/Overview/Limitations for more infos about the limited memory.

To debug these "weird" errors there is really just the possibility to comment in and out memory consuming features of your code and see how much consumes too much.

Also check out this answer for tuning suggestions.

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Asked: 2015-02-02 03:39:20 -0500

Seen: 756 times

Last updated: Apr 02 '15