#WioTerminal – Getting JSON data from an #Azure ☁️ Function !

Hi !

In today’s post I’ll share an scenario about:

Invoke an Azure Function to get JSON data

In my Digital Twin scenario, I got an Azure Function that returns the current state of a Digital Twin door. The response from the function is similar to this one:

{
    "state": 0,
    "desc": "closed",
    "source": "blog"
}

So, once the Wio Terminal has internet access, I can invoke the Azure Function and read the value with the door state. In example, for a door open state:

Wio Terminal Azure Function Response door closed

And for the door open:

Wio Terminal Azure Function Response door open

Important: The sample code is based on the work from Rui Santos, in the article [ESP32 HTTP GET and HTTP POST with Arduino IDE (JSON, URL Encoded, Text)].

I updated the code to work with the specific WiFi and HTTPClient libraries for the Wio Terminal.

Source Code

As usual, the full code is below and some notes

As mentioned before, this sample uses the Wio Terminal specific libraries for Wifi and HTTPClient libraries .
The request to the Azure Function for the IoT Door state will be performed every 10 seconds.
I added a couple of functions at the end of the ino file to display the information on the TFT screen.
In line 98 the HTTP GET process start. After reading the code for the HTTP Library, I realized that I need to define a timeout (3 seconds) and also invoke the end() function before init the http variable.

	/*
	Bruno Capuano, https://www.elbruno.com
	Based on Rui Santos post, https://RandomNerdTutorials.com/esp32-http-get-post-arduino/

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files.

	The above copyright notice and this permission notice shall be included in all
	copies or substantial portions of the Software.
	*/

	#include "rpcWiFi.h"
	#include <HTTPClient.h>
	#include"TFT_eSPI.h"
	TFT_eSPI tft;

	// WiFi information
	const char* ssid = "WiFi Name";
	const char* password = "WiFi password";
	int connectingSeconds = 0;

	// Set timer to 10 seconds
	unsigned long lastTime = 0;
	unsigned long timerDelay = 10000;

	// Azure Function
	String acFncResponse;

	// TFT Display
	const int col0 = 20;
	const int row0 = 30;
	const int row1 = 55;
	const int row2 = 80;
	const int row3 = 105;
	const int row4 = 130;

	void setup() {
	Serial.begin(115200);

	tft.begin();
	tft.setRotation(3);
	tft.fillScreen(TFT_BLACK);
	tft.setTextSize(2);

	tftPrintLine(row0, "El Bruno – @elbruno", "");
	tftPrintLine(row1, "Connecting to WiFi…", "");

	// Set WiFi to station mode and disconnect from an AP if it was previously connected
	Serial.println("Connecting");
	WiFi.mode(WIFI_STA);
	WiFi.disconnect();
	WiFi.begin(ssid, password);

	// attempt to connect to Wifi network:
	while (WiFi.status() != WL_CONNECTED) {
	connectingSeconds++;
	tftPrintLine(row2, "Seconds waiting: ", String(connectingSeconds));
	// wait 1 second for re-trying
	delay(1000);
	WiFi.begin(ssid, password);
	}

	tftPrintLine(row3, "Connected!", "");

	Serial.println("");
	Serial.print("Connected to WiFi network with IP Address: ");
	Serial.println(WiFi.localIP());
	Serial.println("Timer set to 10 seconds (timerDelay variable), it will take 10 seconds before publishing the first reading.");
	delay(2000);

	// Clean screen to show results
	tftInit();
	}

	void loop() {

	if ((millis() – lastTime) > timerDelay) {

	//Check WiFi connection status
	if(WiFi.status()== WL_CONNECTED){

	acFncResponse = httpGETRequest();
	Serial.println(acFncResponse);
	tftPrintLineCol(0, row3, String(acFncResponse), "");
	}
	else {
	Serial.println("WiFi Disconnected");
	tftPrintLine(row3, WiFi Disconnected, "");
	}
	lastTime = millis();
	}
	}

	String httpGETRequest() {

	Serial.println("Start http GET request");

	HTTPClient http;
	http.end();
	http.setTimeout(3000);
	http.begin(" Azure Function Url ");

	int httpResponseCode = http.GET();
	Serial.println("http GET done");

	String payload = ""; //"{}";

	if (httpResponseCode>0) {
	Serial.print("HTTP Response code: ");
	Serial.println(httpResponseCode);
	payload = http.getString();
	}
	else {
	Serial.print("Error code: ");
	Serial.println(httpResponseCode);
	}
	// Free resources
	http.end();

	return payload;
	}

	void tftInit(){
	tft.fillScreen(TFT_BLACK);
	tftPrintLine(row0, "El Bruno – @elbruno", "");
	tftPrintLine(row1, "Azure IoT Door State", "");
	}

	void tftPrintLineCol(int col, int row, String messagePrefix, String message){
	tft.setCursor(col, row);
	tft.print(messagePrefix);
	tft.setCursor((col0 + tft.textWidth(messagePrefix)), row);
	tft.print(message);
	}

	void tftPrintLine(int row, String messagePrefix, String message){
	tftPrintLineCol(col0, row, messagePrefix, message);
	}

view raw WioTerminalAzFunctionInvoke.ino hosted with ❤ by GitHub

Now we are connected, so we can start to interact with Azure resources !

Happy coding!

Greetings

El Bruno

References

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#WioTerminal – Getting JSON data from an #Azure ☁️ Function !

Invoke an Azure Function to get JSON data

Source Code

References

¿Con ganas de ponerte al día?

WioTerminal – Posts to interact with a Digital Twin Door 🚪 with Azure IoT ☁️ and Azure Functions

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Invoke an Azure Function to get JSON data

Source Code

References

¿Con ganas de ponerte al día?

WioTerminal – Posts to interact with a Digital Twin Door 🚪 with Azure IoT ☁️ and Azure Functions

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