ros_BlinkTestMy

#include <ros.h>
#include <std_msgs/Int8.h>

ros::NodeHandle  nh;

void messageCb( const std_msgs::Int8& toggle_msg){
  if (toggle_msg.data==4){
  digitalWrite(LED_BUILTIN, HIGH-digitalRead(LED_BUILTIN));   // blink the led
  }
}

ros::Subscriber<std_msgs::Int8> sub("chatter", &messageCb );

void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
  nh.initNode();
  nh.subscribe(sub);
}

void loop()
{
  nh.spinOnce();
  delay(500);
}