Connecting to web services via the RAK611 Dash Button

Introduction

The last project talked about using the RAK611 dash button hardware to connect to the hivemq mqtt broker services and relay information to you connected Sonoff switches.

If you missed that tutorial click below:

https://www.hackster.io/naresh-krish/diy-remote-wifi-switch-using-the-rak-dashbutton-09b0de

This tutorial takes the next step of connecting your Dash button to the HTTP services provided by the Sonoff switches and OpenHAB to control your home appliances. The principles described here are common to any web service API that you want to access with a connected device and I want the reader to understand these basics thoroughly in order to incorporate these into any IoT project in the future.

The main idea behind the project is to provide kids with a safe way to control their room lights/fans etc using wifi remote switches instead of directly working their way with the electrical sockets/switches. Also these switches can be placed and/or relocated anywhere in the house and they can still control the appliances via web services

About HTTP(s):

According to wikipedia:

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems.[1] HTTP is the foundation of data communication for the World Wide Web.

Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.

Umm....thats the book definition and is accurate. But let me put it this way.

HTTP provides a user with a set of protocols using which a person can interact with a website/webpage/web service

HTTP(s) is nothing but a more secure form of HTTP and i would recommmend readers to use HTTPs services in all their future projects. the RAK611 hardware has full support for HTTPs endpoints. COOL huh ??

HTTP Web services:

Web services are similar to websites/pages in the sense they talk to users via the http protocol and are run from a dedicated server. However there is big difference. Web services do not usual provide a UI. They are somewhat headless and hence they are used to only read/update/add information to and from them using something called REST APIs.

Web services host a database layer which stores all this information and all reads/updates happen on this database.

REST APIs are the interface that the web services provides for the users to access the services. a typical webservice api would look like this

GET https://www.google.co.in/search?q=web+service

The first portion is called the HTTP action or verb. Here it says GET which means it is just going to READ information from the web services.

The second is the web service URL with some paramaters. This is a typical web services from google to search for a query. The term "search" in the URL is one of the web services provided by google and takes a paramters called "q" which here is going to be "web+service". Based on the above URL google would then go ahead and read its database to get information about the search term and provide you with a nice GUI. However this is an example where google not only provides the results but also a UI to present it. Not all webservices would do that. Usually web services would provide output in what is called a JSON object.

JavaScript Object Notation or JSON is an open-standard file format that uses human-readable text to transmit data objects consisting of attribute–value pairs and array data types (or any other serializable value). It is a very common data format used for asynchronousbrowser–server communication, including as a replacement for XML in some AJAX-style systems.

example:

{ "glossary":{ "title":"example glossary", "GlossDiv":{ "title":"S", "GlossList":{ "GlossEntry":{ "ID":"SGML", "SortAs":"SGML", "GlossTerm":"Standard Generalized Markup Language", "Acronym":"SGML", "Abbrev":"ISO 8879:1986", "GlossDef":{ "para":"A meta-markup language, used to create markup languages such as DocBook.", "GlossSeeAlso":[ "GML", "XML" ] }, "GlossSee":"markup" } } } } }

We wont go in-depth into JSON, but lets just know that JSON is the most common format of sending or receiving data from a web service. Other formats include XML, SOAP etc

The Sonoff switches web services.

Its interesting to note that microcotrollers have come a long way from being able to struggle to process a math calculation for hours to something like hosting a small web service inside them. The Sonoff tasmota firmware running on the ESP8266 powered sonoff switches is a find example of this modern trend.

The Sonoff tasmota firmware provides a plethors of HTTP commands to control the appliances connected to them:

http://sonoff_IP/cm?cmnd=Power%20TOGGLE

http://sonoff_IP/cm?cmnd=Power%20On

http://sonoff_IP/cm?cmnd=Power%20off

http://sonoff_IP/cm?user=admin&password=joker&cmnd=Power%20Toggle

This looks very similar to the google IP. Lets break it down.

• The sonoff_IP is the ip address of the switches. much like the google url

• The cm is one of the service provided by this endpoint and is called the command interface of the sonoff switches

• it takes a parameter called cmnd to which you can send commands like POWER2 TOGGLE. see here that the space between the commands is converted to a %20 which is called url escaping.

Now these commands are the basis for our project and lets see how we can incorporate that into our firmware:

The Dash buttom HTTP firmware:

The RAK611 is powerful tool for getting a physical circuit to connect to the internet to control things in some very interesting ways. The RTL8711 is by itself a powerful wifi controller capable of a plethora of connectivity and supports HTTPs

To understand how to setup the RAK 611 dash button firmware follow the project here:

https://www.hackster.io/naresh-krish/diy-remote-wifi-switch-using-the-rak-dashbutton-09b0de

Once you have the hardware and software ready continue as below:

The Firmware:

here is the good parts and the arduino AMEBA SDK firmware that we will push to the Dashbutton.

#include <HttpClient.h> 
#include <WiFi.h> 
#include <WiFiClient.h> 
 
#define LED1  0 
#define LED2  1 
#define LED3  2 
#define LED4  3 
#define RED   0 
#define GREEN 1 
#define BLUE  2 
#define OFF   3 
 
void printWifiStatus(); 
void led_off(); 
void http_get(char* str); 
void led_ctrl(uint8_t led_num, uint8_t rgb); 
 
char ssid[] = "xxxx"; //  your network SSID (name)  
char pass[] = "xxxx";    // your network password (use for WPA, or use as key for WEP) 
int keyIndex = 0;            // your network key Index number (needed only for WEP) 
// Name of the server we want to connect to 
const char kHostname[] = "sonoff_switch_ip_here"; 
const char kPath[] = "/cm?cmnd=Power%20TOGGLE"; 
const int kHttpPort = 80; 
 
// Number of milliseconds to wait without receiving any data before we give up 
const int kNetworkTimeout = 30*1000; 
 
// Number of milliseconds to wait if no data is available before trying again 
const int kNetworkDelay = 1000; 
int status = WL_IDLE_STATUS; 
 
/* power enable */ 
int pwr_en = 15; 
/* leds */ 
int led1_r = 25; 
int led1_g = 24; 
int led1_b = 19; 
int led2_r = 0; 
int led2_g = 2; 
int led2_b = 6; 
int led4_r = 12; 
int led4_g = 11; 
int led4_b = 13; 
int led3_r = 22; 
int led3_g = 21; 
int led3_b = 1; 
 
/* keys */ 
int key1 = 23; 
int key2 = 14; 
int key3 = 10; 
int key4 = 20; 
 
void setup() 
{ 
 Serial.begin(9600);  
 pinMode(pwr_en, OUTPUT); 
 digitalWrite(pwr_en, 1); 
 pinMode(led2_r, OUTPUT); 
 pinMode(led2_g, OUTPUT); 
 pinMode(led2_b, OUTPUT); 
 pinMode(led1_b, OUTPUT); 
 pinMode(led3_r, OUTPUT); 
 pinMode(led3_g, OUTPUT); 
 pinMode(led3_b, OUTPUT); 
 pinMode(led4_b, OUTPUT); 
 pinMode(key2, INPUT_PULLUP); 
 pinMode(key3, INPUT_PULLUP); 
 pinMode(key4, INPUT_PULLUP); 
 
#if 1 
/*   
*   Pin D21-D25 can not be used as digital IO ,when in debug mode(Enable JTAG).  
*   D21-D25 can be used as digital IO when in factory mode.(Disable JTAG)   
*/ 
 //D21-D25 
 pinMode(led4_g, OUTPUT); 
 pinMode(led4_r, OUTPUT); 
 pinMode(led1_g, OUTPUT); 
 pinMode(led1_r, OUTPUT); 
 pinMode(key1, INPUT_PULLUP); 
#endif 
 led_off(); 
 while ( status != WL_CONNECTED) {  
   Serial.print("Attempting to connect to SSID: "); 
   Serial.println(ssid); 
   status = WiFi.begin(ssid, pass); 
   // wait 10 seconds for connection: 
   delay(10000); 
 }  
 Serial.println("Connected to wifi"); 
 printWifiStatus(); 
} 
 
void loop() 
{ 
 led_off(); 
 if (digitalRead(key1) == 0) { 
   delay(50); 
   if (digitalRead(key1) == 0) { 
   led_ctrl(LED1,BLUE);  
   delay(500);  
   Serial.print("key1"); 
   http_get("1"); 
   } 
 } 
 if (digitalRead(key2) == 0) { 
   delay(50); 
   if (digitalRead(key2) == 0) { 
   led_ctrl(LED2,BLUE);   
   delay(500); 
   Serial.print("key2"); 
   http_get("2"); 
   } 
 } 
 if (digitalRead(key3) == 0) { 
   delay(50); 
   if (digitalRead(key3) == 0) { 
   led_ctrl(LED3,BLUE);   
   delay(500); 
   Serial.print("key3"); 
   http_get("3"); 
   } 
 } 
 if (digitalRead(key4) == 0) { 
   delay(50); 
   if (digitalRead(key4) == 0) { 
   led_ctrl(LED4,BLUE);   
   delay(500); 
   Serial.print("key4"); 
   http_get("4"); 
   } 
 }   
delay(100); 
} 
 
void printWifiStatus() { 
 // print the SSID of the network you're attached to: 
 Serial.print("SSID: "); 
 Serial.println(WiFi.SSID()); 
 // print your WiFi shield's IP address: 
 IPAddress ip = WiFi.localIP(); 
 Serial.print("IP Address: "); 
 Serial.println(ip); 
 // print the received signal strength: 
 long rssi = WiFi.RSSI(); 
 Serial.print("signal strength (RSSI):"); 
 Serial.print(rssi); 
 Serial.println(" dBm"); 
 led_ctrl(LED1,RED); 
 led_ctrl(LED2,RED); 
 led_ctrl(LED3,RED); 
 led_ctrl(LED4,RED); 
 delay(500); 
} 
 
void led_off() { 
  led_ctrl(LED1,OFF); 
  led_ctrl(LED2,OFF); 
  led_ctrl(LED3,OFF); 
  led_ctrl(LED4,OFF); 
} 
 
void http_get(char* str) { 
 int err = 0; 
 WiFiClient c; 
 HttpClient http(c); 
 char path[100]; 
 sprintf(path,"%s%s", kPath, str); 
 err = http.get(kHostname, kHttpPort, kPath); 
 Serial.println(path); 
 if (err == 0) 
 { 
   Serial.println("startedRequest ok"); 
   err = http.responseStatusCode(); 
   if (err >=0) 
   { 
     Serial.print("Got status code: "); 
     Serial.println(err); 
   } 
   else 
   {     
     Serial.print("Getting response failed: "); 
     Serial.println(err); 
   } 
 } 
 else 
 { 
   Serial.print("Connect failed: "); 
   Serial.println(err); 
 } 
 http.stop(); 
} 
 
void led_ctrl(uint8_t led_num, uint8_t rgb) 
{ 
 switch (led_num) { 
   case LED1: 
     if (rgb == RED) { 
       digitalWrite(led1_r, 0); 
       digitalWrite(led1_g, 1); 
       digitalWrite(led1_b, 1); 
     } 
     else if (rgb == GREEN) { 
       digitalWrite(led1_r, 1); 
       digitalWrite(led1_g, 0); 
       digitalWrite(led1_b, 1); 
     } 
     else if (rgb == BLUE) { 
       digitalWrite(led1_r, 1); 
       digitalWrite(led1_g, 1); 
       digitalWrite(led1_b, 0); 
     } 
     else if (rgb == OFF) { 
       digitalWrite(led1_r, 1); 
       digitalWrite(led1_g, 1); 
       digitalWrite(led1_b, 1); 
     } 
     break; 
   case LED2: 
     if (rgb == RED) { 
       digitalWrite(led2_r, 0); 
       digitalWrite(led2_g, 1); 
       digitalWrite(led2_b, 1); 
     } 
     else if (rgb == GREEN) { 
       digitalWrite(led2_r, 1); 
       digitalWrite(led2_g, 0); 
       digitalWrite(led2_b, 1); 
     } 
     else if (rgb == BLUE) { 
       digitalWrite(led2_r, 1); 
       digitalWrite(led2_g, 1); 
       digitalWrite(led2_b, 0); 
     } 
     else if (rgb == OFF) { 
       digitalWrite(led2_r, 1); 
       digitalWrite(led2_g, 1); 
       digitalWrite(led2_b, 1); 
     } 
     break; 
   case LED3: 
     if (rgb == RED) { 
       digitalWrite(led3_r, 0); 
       digitalWrite(led3_g, 1); 
       digitalWrite(led3_b, 1); 
     } 
     else if (rgb == GREEN) { 
       digitalWrite(led3_r, 1); 
       digitalWrite(led3_g, 0); 
       digitalWrite(led3_b, 1); 
     } 
     else if (rgb == BLUE) { 
       digitalWrite(led3_r, 1); 
       digitalWrite(led3_g, 1); 
       digitalWrite(led3_b, 0); 
     } 
     else if (rgb == OFF) { 
       digitalWrite(led3_r, 1); 
       digitalWrite(led3_g, 1); 
       digitalWrite(led3_b, 1); 
     } 
     break; 
   case LED4: 
     if (rgb == RED) { 
       digitalWrite(led4_r, 0); 
       digitalWrite(led4_g, 1); 
       digitalWrite(led4_b, 1); 
     } 
     else if (rgb == GREEN) { 
       digitalWrite(led4_r, 1); 
       digitalWrite(led4_g, 0); 
       digitalWrite(led4_b, 1); 
     } 
     else if (rgb == BLUE) { 
       digitalWrite(led4_r, 1); 
       digitalWrite(led4_g, 1); 
       digitalWrite(led4_b, 0); 
     } 
     else if (rgb == OFF) { 
       digitalWrite(led4_r, 1); 
       digitalWrite(led4_g, 1); 
       digitalWrite(led4_b, 1); 
     } 
     break; 
   default: 
     break; 
 } 
} 

Lets break down the AMEBA SDK code here shall we

#include <HttpClient.h> 
#include <WiFi.h> 
#include <WiFiClient.h> 

Here we include the three main header files from the SDK. the two wifi headers for the hardware related stuff and the HTTP client for controlling our HTTP requests.

#define LED1  0 
#define LED2  1 
#define LED3  2 
#define LED4  3 
#define RED   0 
#define GREEN 1 
#define BLUE  2 
#define OFF   3 

Here we define the LEDs on the Dash button board and the RGB mapping as well.

char ssid[] = "xxxxx"; //  your network SSID (name)  
char pass[] = "xxxxx";    // your network password (use for WPA, or use as key for WEP) 

This portion specifies which accesspoint should the board connect to in order to access the internet

const char kHostname[] = "sonoff_switch_ip_here"; 
const char kPath[] = "/cm?cmnd=Power%20TOGGLE"; 
const int kHttpPort = 80;  

Here we define the webservice endpoint ip and the service command along with paramters to send to it. This is for a single connection sonoff switch. For a dual relay sonoff switch change to

const char kHostname[] = "sonoff_switch_ip_here"; 
const char kPath[] = "/cm?cmnd=Power1%20TOGGLE";  //or Power2
const int kHttpPort = 80;  

The setup funstion just intiitalises the Serial port and :

while ( status != WL_CONNECTED) {  
   Serial.print("Attempting to connect to SSID: "); 
   Serial.println(ssid); 
   status = WiFi.begin(ssid, pass); 
   // wait 10 seconds for connection: 
   delay(10000); 
 }  
 Serial.println("Connected to wifi"); 
 printWifiStatus(); 

While the wifi status is connected, it will keep scanning for the access point and try connecting to it. Once connected it will print the wifi status using printWifiStatus() function.

In loop(), we check the digitalRead status of every button and ifany one of the button is clicked, we send the HTTP request to our sonoff switch using the http_get() function defined later in the code.

Uploading the code

So upload this code by poressing the upload button in the arduino IDE and try clicking any of the buttons on the DASH button, you should hear the relay in you sonoff switch go off and control you appliance.

Notes:

Make sure that the sonof switch is powered on for making the http call.

Also make sure that the sonoff switch and the dash button are on the same wifi router to make these local HTTP calls

OpenHAB integration

OpenHAB is an awesome software to integrate all you smart home appliances under one server. It supports a variety of protocols like HTTP, MQTT, CoAP and also provides cross protocol acces via OpenHAB Integration being written by fellow developers around the world

To have a quick overview on how to install openhab follow the tutorial here:

https://www.hackster.io/naresh-krish/home-automation-using-wiscore-and-openhab-1ec6e4

Once you raspberry pi is setup with OpenHab, Proceed further to control you connected Sonoff switches via OpenHab:

OpenHAB API

Lets look at the openhab API for controlling a registered switch

http://openhab_ip/rest/items/MyLight/state

So we get a similar looking service like earlier. So we have the openhab_ip or domain name followed by te service endpoint "rest/items" and it points to the "My Light" switch that you have registered on OpenHAB (go through he above tutorial on how to register switches in OpenHAB) and finally the "state" of the switch

Here we have two verbs that this service accepts;

GET and PUT

GET would just simply get the state of the above switch

PUT however would now chnage the servcie parameter called state to what even is in the HTTP PUT header.

So lets see what you would have to chnage in your code

1) Introduce a new function http_put() like so

void http_post(char* data) { 
 int err = 0; 
 WiFiClient client; 
 while(1){ 
 if (!client.connect("xxxxxxx", 8080)) {                             //port can be 8080 or as configured in the openhab config 
     Serial.println("Connect to server failed. Retry after 1s."); 
     client.stop(); 
     delay(1000); 
     continue; 
  }else{ 
   break; 
  } 
 } 
   Serial.println("connected to server"); 
   // Make a HTTP request: 
   client.print("POST /rest/items/My_Item/"); 
   client.print(data); 
   client.print("Host: "); 
   client.println("xxxxxxx"); //you open hab url in the form abc.xyz.com 
   client.println(); 
   while (!client.available()) delay(100); 
   while (client.available()) { 
     char c = client.read(); 
     Serial.write(c); 
   } 
   client.stop(); 
} 

This function would send the command called OFF to the My_Item switch as we discussed. to use it call:

http_post("OFF")

in your switch read code (where you check the status of digitalRead()) and when you press the associated button, the appliance will be switched off.

if you want to swicth on send:

http_port("ON")

This tutorial was a sample implementation of the HTTP methods in the Ameba SDK. In the next tutorial, we will tackle more complex integration with IFTTT web service and Node-RED integration.