Arduino ESP32 : HTTP(S) POST Request to IBM Watson IoT on Button Press

Abhishek Ghosh

By Abhishek Ghosh March 10, 2019 10:52 am Updated on March 10, 2019

Arduino ESP32 : HTTP(S) POST Request to IBM Watson IoT on Button Press

Here is How to Send an HTTP POST Request to IBM Watson IoT on Button Press from Arduino ESP32. The basic is dependent on our earlier two separate examples, first is the set of working examples of codes for IBM Watson IoT and second is the example of using a button press to make a LED turn on for a pre-defined time. Earlier, we had another example of using Blynk to send a basic push message on a button press. That Bylnk’s example was for satisfying peoples who want a quick fix in an easy way. That way is not methodical, it abstracts the software and hardware too much, also not reliable.

There is nothing new to say about how to setup ESP32 to use with Arduino IDE.

If you want the code, that is readily available on our GitHub repo. We want to say something on HTTP POST of IBM Watson IoT.

To securely send an event called myEvent to the platform with organisation id ‘xfd8ls’, device id HTTPDevice and device type HTTPdeviceType we issue this POST request:

https://xfd8ls.messaging.internetofthings.ibmcloud.com:8883/api/v0002/device/types/HTTPdeviceType/devices/HTTPDevice/events/myEvent

1	https://xfd8ls.messaging.internetofthings.ibmcloud.com:8883/api/v0002/device/types/HTTPdeviceType/devices/HTTPDevice/events/myEvent

From the above example, you have to keep polling the server to see if there was a message waiting. That is fine for some purposes. We can set the body of the message to:

---

{"waitTimeSecs": 10}

1	{"waitTimeSecs": 10}

The number represents a number of seconds. This way you can effectively set your code to wait for a command to arrive. This official guide talking about the thing we are doing but in complex way with Raspberry Pi :

https://developer.ibm.com/recipes/tutorials/publish-device-events-to-ibm-iot-foundation-using-https/

1	https://developer.ibm.com/recipes/tutorials/publish-device-events-to-ibm-iot-foundation-using-https/

And here is more detailed documentation :

https://console.bluemix.net/docs/services/IoT/devices/api.html#api

1	https://console.bluemix.net/docs/services/IoT/devices/api.html#api

For our this code, you will get the raw data from the Recent Events tab on IBM Watson IoT Platform and also, the
Logs there will show authentication, connection and disconnection. These facts proves that remote server “understood” your button press. Also on Arduino IDE’s serial console, you will get meaningful output. This is a meaningful illustration :

Arduino ESP32 HTTPS POST Request to IBM Watson IoT on Button Press

Here are more useful docs :

https://developer.ibm.com/recipes/tutorials/publish-device-events-to-ibm-iot-foundation-using-https/
https://www.ibm.com/support/knowledgecenter/en/SSQP8H/iot/platform/devices/api.html

1 2	https://developer.ibm.com/recipes/tutorials/publish-device-events-to-ibm-iot-foundation-using-https/ https://www.ibm.com/support/knowledgecenter/en/SSQP8H/iot/platform/devices/api.html

And here is the full code :

// connects once upon pressing ESP32 boot pushbutton (GPIO 0) button and sends a message, closes connection
// written by Dr. Abhishek Ghosh, https://thecustomizewindows.com
// released under GNU GPL 3.0



const byte BUTTON=0; // boot button pin (built-in on ESP32)
const byte LED=2; // onboard LED (built-in on ESP32)

#include <WiFi.h>
#include <WiFiMulti.h>
#include <HTTPClient.h>
#include <base64.h>
#define USE_SERIAL Serial 
 
unsigned long buttonPushedMillis; // when button was released
unsigned long ledTurnedOnAt; // when led was turned on
unsigned long turnOnDelay = 20; // wait to turn on LED
unsigned long turnOffDelay = 5000; // turn off LED after this time
bool ledReady = false; // flag for when button is let go
bool ledState = false; // for LED is on or not.

const char* ssid = "your wifi hotspot";
const char* password = "password of the above";

#define ORG "your org on ibm" 
#define DEVICE_TYPE "name you given"
#define DEVICE_ID "name you given"
#define TOKEN "your token"
#define EVENT "myEvent" // example

// <------- CHANGE PARAMETERS ABOVE THIS LINE ------------>

String urlPath = "/api/v0002/device/types/" DEVICE_TYPE "/devices/" DEVICE_ID "/events/" EVENT;
String urlHost = ORG ".messaging.internetofthings.ibmcloud.com";
int urlPort = 8883;
String authHeader;
 
void setup() {
 pinMode(BUTTON, INPUT_PULLUP);
 pinMode(LED, OUTPUT);
 digitalWrite(LED, LOW);
 Serial.begin(115200); Serial.println(); 
 initWifi();
 authHeader = "Authorization: Basic " + base64::encode("use-token-auth:" TOKEN) + "\r\n";
}
 
void loop() {
 // get the time at the start of this loop()
 unsigned long currentMillis = millis(); 
 // check the button
 if (digitalRead(BUTTON) == LOW) {
  // update the time when button was pushed
  buttonPushedMillis = currentMillis;
  ledReady = true;
 }
  
 // make sure this code isn't checked until after button has been let go
 if (ledReady) {
   //this is typical millis code here:
   if ((unsigned long)(currentMillis - buttonPushedMillis) >= turnOnDelay) {
     // okay, enough time has passed since the button was let go.
     digitalWrite(LED, HIGH);
     doWiFiClientSecure();
     // setup our next "state"
     ledState = true;
     // save when the LED turned on
     ledTurnedOnAt = currentMillis;
     // wait for next button press
     ledReady = false;
   }
 }
  
 // see if we are watching for the time to turn off LED
 if (ledState) {
   // okay, led on, check for now long
   if ((unsigned long)(currentMillis - ledTurnedOnAt) >= turnOffDelay) {
     ledState = false;
     digitalWrite(LED, LOW);
   }
 }
}

void doWiFiClientSecure() {
 WiFiClientSecure client;
 Serial.print("connect: "); Serial.println(urlHost);
 while ( ! client.connect(urlHost.c_str(), urlPort)) {
    Serial.print(".");
 }
 Serial.println("Connected");
 String postData = String("{  \"d\": {\"aMessage\": \"") + millis()/1000 + "\"}  }";
 String msg = "POST " + urlPath + " HTTP/1.1\r\n"
                "Host: " + urlHost + "\r\n"
                "" + authHeader + ""
                "Content-Type: application/json\r\n"
                "Content-Length: " + postData.length() + "\r\n"
                "\r\n" + postData;
                
 client.print(msg);
 Serial.print(msg);

 Serial.print("\n*** Request sent, receiving response...");
 while (!!!client.available()) {
    delay(50);
 Serial.print(".");
  }
  
Serial.println();
Serial.println("Got response");  
  while(client.available()){
  Serial.write(client.read());
  }
Serial.println(); Serial.println("closing connection");
  client.stop();
}

void initWifi() {
  Serial.print("Connecting to: "); Serial.print(WiFi.SSID());
  WiFi.mode(WIFI_STA);   
  WiFi.begin(ssid, password);  
  while (WiFi.status() != WL_CONNECTED) {
     delay(250);
     Serial.print(".");
  }
  
  Serial.println("");
  Serial.print("WiFi connected, IP address: "); Serial.println(WiFi.localIP());

}

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// connects once upon pressing ESP32 boot pushbutton (GPIO 0) button and sends a message, closes connection

// written by Dr. Abhishek Ghosh, https://thecustomizewindows.com

// released under GNU GPL 3.0

const byte BUTTON=0; // boot button pin (built-in on ESP32)

const byte LED=2; // onboard LED (built-in on ESP32)

#include <WiFi.h>

#include <WiFiMulti.h>

#include <HTTPClient.h>

#include <base64.h>

#define USE_SERIAL Serial

unsigned long buttonPushedMillis; // when button was released

unsigned long ledTurnedOnAt; // when led was turned on

unsigned long turnOnDelay = 20; // wait to turn on LED

unsigned long turnOffDelay = 5000; // turn off LED after this time

bool ledReady = false; // flag for when button is let go

bool ledState = false; // for LED is on or not.

const char* ssid = "your wifi hotspot";

const char* password = "password of the above";

#define ORG "your org on ibm"

#define DEVICE_TYPE "name you given"

#define DEVICE_ID "name you given"

#define TOKEN "your token"

#define EVENT "myEvent" // example

// <------- CHANGE PARAMETERS ABOVE THIS LINE ------------>

String urlPath = "/api/v0002/device/types/" DEVICE_TYPE "/devices/" DEVICE_ID "/events/" EVENT;

String urlHost = ORG ".messaging.internetofthings.ibmcloud.com";

int urlPort = 8883;

String authHeader;

void setup() {

pinMode(BUTTON, INPUT_PULLUP);

pinMode(LED, OUTPUT);

digitalWrite(LED, LOW);

Serial.begin(115200); Serial.println();

initWifi();

authHeader = "Authorization: Basic " + base64::encode("use-token-auth:" TOKEN) + "\r\n";

}

void loop() {

// get the time at the start of this loop()

unsigned long currentMillis = millis();

// check the button

if (digitalRead(BUTTON) == LOW) {

// update the time when button was pushed

buttonPushedMillis = currentMillis;

ledReady = true;

}

// make sure this code isn't checked until after button has been let go

if (ledReady) {

//this is typical millis code here:

if ((unsigned long)(currentMillis - buttonPushedMillis) >= turnOnDelay) {

// okay, enough time has passed since the button was let go.

digitalWrite(LED, HIGH);

doWiFiClientSecure();

// setup our next "state"

ledState = true;

// save when the LED turned on

ledTurnedOnAt = currentMillis;

// wait for next button press

ledReady = false;

}

// see if we are watching for the time to turn off LED

if (ledState) {

// okay, led on, check for now long

if ((unsigned long)(currentMillis - ledTurnedOnAt) >= turnOffDelay) {

ledState = false;

digitalWrite(LED, LOW);

}

void doWiFiClientSecure() {

WiFiClientSecure client;

Serial.print("connect: "); Serial.println(urlHost);

while ( ! client.connect(urlHost.c_str(), urlPort)) {

Serial.print(".");

}

Serial.println("Connected");

String postData = String("{ \"d\": {\"aMessage\": \"") + millis()/1000 + "\"} }";

String msg = "POST " + urlPath + " HTTP/1.1\r\n"

"Host: " + urlHost + "\r\n"

"" + authHeader + ""

"Content-Type: application/json\r\n"

"Content-Length: " + postData.length() + "\r\n"

"\r\n" + postData;

client.print(msg);

Serial.print(msg);

Serial.print("\n*** Request sent, receiving response...");

while (!!!client.available()) {

delay(50);

Serial.print(".");

}

Serial.println();

Serial.println("Got response");

while(client.available()){

Serial.write(client.read());

}

Serial.println(); Serial.println("closing connection");

client.stop();

}

void initWifi() {

Serial.print("Connecting to: "); Serial.print(WiFi.SSID());

WiFi.mode(WIFI_STA);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(250);

Serial.print(".");

}

Serial.println("");

Serial.print("WiFi connected, IP address: "); Serial.println(WiFi.localIP());

}

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Arduino ESP32 : HTTP(S) POST Request to IBM Watson IoT on Button Press

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