rosserial_python can't connect to Arduino Leonardo

Question

I am trying to use an Arduino to connect two sensors to ROS Groovy on Ubuntu 12.04 but have problems to talk to it using rosserial. Since I have several sensors, I bought the Arduino Leonardo http://arduino.cc/en/Main/arduinoBoardLeonardo based on the ATmega32u4 since it has four interrupt pins that I need for my sensors.

The first problem was in ArduinoHardware.h

iostream = &Serial;

which I changed to

iostream = &Serial1;

as proposed here: https://github.com/ros-drivers/rosserial/issues/49

Now the HelloWorld.ino compiled and I could upload it to the Arduino. I started

rosrun rosserial_python serial_node.py /dev/ttyACM0

but only get this response:

[INFO] [WallTime: 1367338659.844329] ROS Serial Python Node

[INFO] [WallTime: 1367338659.858269] Connecting to /dev/ttyACM0 at 57600 baud

[ERROR] [WallTime: 1367338676.969867] Lost sync with device, restarting...

Has someone managed to use the Leonardo and can help me?

Nikolas

// update: I adapted by loop to:

void loop(){

Serial.println(1);

if (state){

digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level)

}else{

digitalWrite(led, LOW); // turn the LED on (HIGH is the voltage level)

}

state = !state;

delay(1000); // wait for a second

str_msg.data = hello;

chatter.publish( &str_msg );

nh.spinOnce();

}

The led (Pin 13) is blinks with a frequency of .5Hz (1s on 1s off). If (Iff) I start the rosserial_python, the TX-Led also flashes as the pin13-Led changes its state. Therefore there is at least some kind of communication, but no rostopic.

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Originally posted by NikolasEngelhard on ROS Answers with karma: 106 on 2013-04-30

Post score: 2

Answer 1

To my knowledge, you can't use the Arduino Serial library while sending/receiving ROS topics.

Since your data will be sent in the chatter.publish call, the rosserial_python node will see this data, as well as data sent with the Serial.println call, which is probably whats causing it to lose sync.

Try commenting out that Serial.println line in loop() and see if it can connect stably.

Also, I noticed that in your python solution you're using a baud rate of 115200, whereas the rosserial node is attempting to connect at 57600. Are you setting the serial rate to 115200 in your void setup() on the Arduino? You'll probably want to remove that as well as it will conflict with the rosserial configuration.

Best of luck!

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Originally posted by hd271 with karma: 38 on 2013-05-01

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by NikolasEngelhard on 2013-05-01:
I first tried it without the serial.println but could also not connect properly. I experimented with different baudrates (and checked that both ends use the same rate) but was not able to connect.

Answer 2

Alternative using python directly

I now stopped working on rosserial and implemented an own python based interface:

#!/usr/bin/env python
import rospy
from std_msgs.msg import String

import serial           
import time
ser = serial.Serial('/dev/ttyACM0', 115200)

pub = rospy.Publisher('chatter', String)
rospy.init_node('talker')


while 1:
 a = ser.readline()
 pub.publish(String(a))

If I have an arduino loop of

void loop() {
   Serial.println("OFF");
}

the frequency is enough for my needs:

rostopic hz chatter

gives be above 10kHz.

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Originally posted by NikolasEngelhard with karma: 106 on 2013-05-01

This answer was NOT ACCEPTED on the original site

Post score: 1

Answer 3

The "Hello World" example seems to be working fine on Hydro. The only change you must to your Arduino code on Leonardo is to add

#define USE_USBCON

just before

#include <ros.h>

That's it.

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Originally posted by bruno.hexsel with karma: 21 on 2014-01-25

This answer was NOT ACCEPTED on the original site

Post score: 2

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Original comments

Comment by honky on 2014-05-21:
This helped me a lot. Thank you!

Comment by ivan_calle on 2017-10-16:
This worked for me also.. Using ros kinetic..!!!! Thanks