Published September 12, 2016 © GPL3+

NubChat - chat app for devices (and humans) with PubNub

NubChat is an app that let communicate with human and devices using pubnub APIs.

BeginnerFull instructions provided1 hour1,990

Things used in this project

Hardware components

Android device

Software apps and online services

PubNub Publish/Subscribe API

Arduino IDE

Story

As the title says, this is an app that let you communicate with your devices using pubnub API's.

I have explained the Android development on Pluralsight. Here I want to explain a sample use with a Linkit ONE board.

Download the app from Google Play Store here.

The first time you use the app it will ask you to chose an username, and for your pubnub keys.

Now press on the "+" button and add a new private channel.

We will use this channel to interact with our board's pins. Here are the functions we will implement:

DRPIN read a digital pin

ARPIN read an analog pin

DWPIN VAL write on a digital pin

AWPIN VAL write on a analog (PWM) pin

In the sketch for Linkit ONE, remember to set your WiFi, and PubNub credentials.

Variable char channel[] must be equal to the channel name you created in the app.

#define WIFI_AP "" // your WiFi_AP name 
#define WIFI_PASSWORD "" //your WiFi password 
#define WIFI_AUTH LWIFI_OPEN // 
char pubkey[] = ""; //Pubnub publish key 
char subkey[] = ""; //pubnub subscribe key 
char channel[] = "LinkitONE"; //a channel for this device

In the main loop we subscribe to the device's channel, and when we get a message, we decode it and do the corresponding action.

So this was just a little example of how this app can be used, but there are many other things that you can do with it. You can also use it as a simple chat app for Android devices.

This is the first release, but I will update it and add other features.

If you have any suggestions about features to add, or there is something that doesn't work, just let me know.

NubChat.ino

#include <ArduinoJson.h>
#include "PubNub.h"
#include "LWiFi.h"
#include "LWiFiClient.h"

#define WIFI_AP "" // your WiFi_AP name
#define WIFI_PASSWORD "" //your WiFi password
#define WIFI_AUTH LWIFI_OPEN //

char pubkey[] = ""; //Pubnub publish key
char subkey[] = ""; //pubnub subscribe key
char channel[] = "LinkitONE"; //a channel for this device

LWiFiClient *client;
DynamicJsonBuffer jsonBuffer;

void setup()
{
  Serial.begin(9600);
  while (!LWiFi.connect(WIFI_AP, LWiFiLoginInfo(WIFI_AUTH, WIFI_PASSWORD)))delay(1000); //wait for a WiFi connection
  PubNub.begin(pubkey, subkey); //setup pubnub

  //Subscribing with REST API always gives an emtpy message at the first call.
  //So we call it once in the setup, to throw away this first message.
  subscribe();
}


void loop()
{
  JsonObject& j1 = jsonBuffer.parseArray(subscribe())[0] ; //Subscribe and convert message to a JSON object
  String text = j1["text"]; //get the message content.

  //Create JSON for response
  JsonObject& j2 = jsonBuffer.createObject();
  j2["sender"] = channel;
  j2["type"] = "0";

  if (text.substring(0, 2).equalsIgnoreCase("DW"))
  {
    int pin = text.substring(2).toInt();
    boolean val = text.substring(text.indexOf(" ") + 1).equalsIgnoreCase("HIGH");
    pinMode(pin, OUTPUT);
    digitalWrite(pin, val);
    j2["text"] = "done";
  }
  else if (text.substring(0, 2).equalsIgnoreCase("AW"))
  {
    int pin = text.substring(2).toInt();
    boolean val = text.substring(text.indexOf(" ") + 1).toInt();
    pinMode(pin, OUTPUT);
    analogWrite(pin, val);
    j2["text"] = "done";
  }
  else if (text.substring(0, 2).equalsIgnoreCase("DR"))
  {
    int pin = text.substring(2).toInt();
    pinMode(pin, INPUT);
    j2["text"] = digitalRead(pin) ? "HIGH" : "LOW";
  }
  else if (text.substring(0, 2).equalsIgnoreCase("AR"))
  {
    int pin = text.substring(2).toInt();
    pinMode(pin, INPUT);
    j2["text"] = analogRead(pin);
  }
  else j2["text"] = "Invalid command";
  String message;
  j1.printTo(message);
  publish(j1["sender"], message.c_str()); //Send response
}

void publish(const char *channel, const char *message)
{
  if (!(client = PubNub.publish(channel, message)))
  {
    Serial.println("publishing error");
    delay(1000);
  }
  while (client->connected())
  {
    while (client->connected() && !client->available());
    client->read();
  }
  client->stop();
}

String subscribe()
{
  String response = "";
  PubSubClient *pclient;
  while (!(pclient = PubNub.subscribe(channel)))
  {
    Serial.println("subscription error");
    delay(1000);
  }
  while (pclient->wait_for_data())response += (char)pclient->read();
  pclient->stop();
  Serial.println(response);
  return response;
}