Next UPDATE: Upload via Arduino IDE works fine (even if newPing,h is included). Upload with atom and platform.io leads to the described error :( But why???

UPDATE: I reduced the code step by step. I found out that #include is responsible for the error messages posted by rosserial. (just the include leads to the error even if I not create any NewPing object)

Any idea?

BR

Marco

Hi, I created a custom message:

SonarDistances.msg 
uint8 front_middle
uint8 right_front 
uint8 right_middle
uint8 right_rear 
uint8 left_front
uint8 left_middle 
uint8 left_rear
uint8 rear_middle

Catkinmake install and creation of the roslib etc. was done. devel path added to .bashrc.

Baud rate on arduino nano was set.

Serial.begin(57600)

Upload to arduino was fine. Now I start roscore and rosserial

rosrun rosserial_python serial_node.py /dev/ttyUSB0

After this I receive continously the following messages in the terminal:

[ERROR] [1521061577.369482]: Tried to publish before configured, topic id 125
[ERROR] [1521061577.434796]: Creation of publisher failed: need more than 1 value to unpack

(continously because I publish on a regular basis) (if i publish only once i only receive on time the id 125 message - after this a lost sync with device and restart is shown)

If I just use a simple chatter rosserial example with a string message the connection works an the topic is shown with rostopic echo.

Any advise?

BR and thanks in advance, Marco

Update: I just start roscore (no launch file) and rosserial.

roscore
rosrun rosserial_python serial_node.py /dev/ttyUSB0

Following code is used on arduino:

#include <ros.h>
#include <hallrover_robo/SonarDistances.h>
#include <NewPing.h>


//############## Sonar Definitions
#define SONAR_NUM     3 // Number or sensors.
#define SONAR_FM      0
#define SONAR_RF      1
#define SONAR_RR      2


#define SONAR_FM_TRIG_PIN 2 //Front middle
#define SONAR_FM_ECHO_PIN 3 //Front middle
#define SONAR_RF_TRIG_PIN 4 //Right front
#define SONAR_RF_ECHO_PIN 5 //Right front
#define SONAR_RR_TRIG_PIN 6 //Right rear
#define SONAR_RR_ECHO_PIN 7 //Right rear

#define MAX_DISTANCE 200
#define PING_INTERVAL 33 // Milliseconds between pings.

unsigned long pingTimer[SONAR_NUM]; // When each pings.
unsigned int cm[SONAR_NUM]; // Store ping distances.
uint8_t currentSensor = 0; // Which sensor is active.

NewPing sonar[SONAR_NUM] = { // Sensor object array.
  NewPing(SONAR_FM_TRIG_PIN, SONAR_FM_ECHO_PIN, MAX_DISTANCE),
  NewPing(SONAR_RF_TRIG_PIN, SONAR_RF_ECHO_PIN, MAX_DISTANCE),
  NewPing(SONAR_RR_TRIG_PIN, SONAR_RR_ECHO_PIN, MAX_DISTANCE),
};


//############### ROS definitions
ros::NodeHandle  nh;
hallrover_robo::SonarDistances sonarDistances;
int isSonarActive;
ros::Publisher sonarDistances_pub("/sonar_distances", &sonarDistances);



void setup() {
  // put your setup code here, to run once:
  Serial.begin(57600) ;
  nh.initNode();
while(!nh.connected()) {nh.spinOnce();} //wait for connection.


  nh.advertise(sonarDistances_pub);
  if (!nh.getParam("hr_sonar_active",&isSonarActive) ) isSonarActive = 0;
//  if (!nh.getParam("hr_sonar_update_frequence",&loop_time) ) loop_time = 1;

//just test
sonarDistances.right_front = 999;
sonarDistances.right_rear = 999;
sonarDistances.right_middle = 111;
sonarDistances.front_middle = 999;
sonarDistances.left_front = 999;
sonarDistances.left_rear = 999;
sonarDistances.left_middle = 111;
sonarDistances.rear_middle = 999;
  sonarDistances_pub.publish(&sonarDistances);
}

void loop()
{
    unsigned int distance;

    if ( isSonarActive == 1)
    {
      for (uint8_t i = 0; i < SONAR_NUM; i++) {
          if (millis() >= pingTimer[i]) {
            pingTimer[i] += PING_INTERVAL * SONAR_NUM;
            if (i == 0 && currentSensor == SONAR_NUM - 1)
              oneSensorCycle(); // Do something with results.
            sonar[currentSensor].timer_stop();
            currentSensor = i;
            cm[currentSensor] = 0;
            sonar[currentSensor].ping_timer(echoCheck);
          }
        }
    nh.spinOnce();
  }
}


void echoCheck() { // If ping echo, set distance to array.
  if (sonar[currentSensor].check_timer())
    cm[currentSensor] = sonar[currentSensor].ping_result / US_ROUNDTRIP_CM;
}

void oneSensorCycle() { // Do something with the results.
  for (uint8_t i = 0; i < SONAR_NUM; i++) {
    switch (i) {
      case SONAR_FM: sonarDistances.front_middle = cm[i];
      case SONAR_RF: sonarDistances.right_front = cm[i];
      case SONAR_RR: sonarDistances.right_rear = cm[i];
    }
  }
  sonarDistances_pub.publish(&sonarDistances);

}