Arduino UNO and ESP8266

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Hei! I decided to continue my project with an Arduino UNO wifi rev2, basically an arduino uno + esp32. I successffully created a ros wifi node that reads accelerations of the embedded IMU and publish them. I put here the code, maybe it can be helpful.

from the command line run:

roscore

and then, in another terminal.

rosrun rosserial_python serial_node.py tcp

If you are experiencing troubles of connection, try using 'ping' on linux. To see your IP adress, 'Hostname -I', take the 192. ... address.

Ah, I am using ros noetic, ubuntu 20.04 and version 0.7.8 of rosserial library. In general, try to run this code with different versions of the rosserial library, since with some I encountered problems.

I really hope I am helping somebody here!! let me know if it works!!

code:

#include <ros.h>
//#include ROSSERIAL_ARDUINO_TCP
#include <std_msgs/Float32.h>
#include <Arduino.h>
#include <SPI.h>
#include <WiFiNINA.h>
#include <Arduino_LSM6DS3.h> // questa è per leggere le accelerazioni


// ====================== MASTER DATA =========================

// metti ip del tuo pc
// roscore
// fai "rosrun rosserial_python serial_node.py tcp" e aspetta tanto
// usa ping + ip adress dell'arduino per vedere se funziona
//IPAddress server(192,178,82,123);
IPAddress server(192,178,82,126);
WiFiClient client;


//======================= WIFI CLASS DEFINITION ========================

class WiFiHardware {

  public:
  WiFiHardware() {};

  void init() {
    // do your initialization here. this probably includes TCP server/client setup
     client.connect(server, 11411);//11411
  }

  // read a byte from the serial port. -1 = failure
  int read() {
    // implement this method so that it reads a byte from the TCP connection and returns it
    //  you may return -1 is there is an error; for example if the TCP connection is not open
    return client.read();         //will return -1 when it will works
  }

  // write data to the connection to ROS
  void write(uint8_t* data, int length) {
    // implement this so that it takes the arguments and writes or prints them to the TCP connection
    for(int i=0; i<length; i++)
      client.write(data[i]);
  }

  // returns milliseconds since start of program
  unsigned long time() {
     return millis(); // easy; did this one for you
  }
};

//======================= VARIABLE DEFINITION ========================

char ssid[] = "network_name";
char pass[] = "network_password";
ros::NodeHandle_<WiFiHardware> nh; // here I say to ROS that I am using the WiFiHardware to manage ros

std_msgs::Float32 acc_x_msg;                     // acceleration on x-body axis
ros::Publisher pub_acc_x("acc_x", &acc_x_msg);
std_msgs::Float32 acc_y_msg;                     // acceleration on y-body axis
ros::Publisher pub_acc_y("acc_y", &acc_y_msg);
std_msgs::Float32 acc_z_msg;                     // acceleration on z-body axis
ros::Publisher pub_acc_z("acc_z", &acc_z_msg);
std_msgs::Float32 om_x_msg;                      // angular velocity on x-body axis
ros::Publisher pub_om_x("om_x", &om_x_msg);
std_msgs::Float32 om_y_msg;                      // angular velocity on y-body axis
ros::Publisher pub_om_y("om_y", &om_y_msg);
std_msgs::Float32 om_z_msg;                      // angular velocity on z-body axis
ros::Publisher pub_om_z("om_z", &om_z_msg);

//============================ SETUP =====================================

void setup() {
  Serial.begin(9600);

  // wifi setup:
  Serial.println("\nStarting connection to server...");
  WiFi.begin(ssid, pass);
  Serial.println("\nconnected to server");
  delay(10000);

  // accellerometer setup:
  IMU.begin();
  delay(10000);

  // ros setup:
  nh.initNode();
  nh.advertise(pub_acc_x);
  nh.advertise(pub_acc_y);
  nh.advertise(pub_acc_z);
  nh.advertise(pub_om_x);
  nh.advertise(pub_om_y);
  nh.advertise(pub_om_z);

  delay(10000);

}

//============================ LOOP =====================================

void loop() {

   // accellerometer ...