Reading data from ThingSpeak via Arduino Uno+ESP8266

Question

I am integrating thingspeak and arduino plus Esp8266 mean making a simple project which contain my android app to update the thingspeak channel and then want to read the data of that channel via arduino uno. the android parts works fine but at the arduino side i got stuck and unable to read the channel data via esp8266(attached to my arduino uno). Here is my code.any help would be appreciated. it shows in serial monitor connecting to thingspeak.com and show nothing next.

#include "WiFiEsp.h"
// Emulate Serial1 on pins 6/7 if not present
#ifndef HAVE_HWSERIAL1
#include "SoftwareSerial.h"
SoftwareSerial Serial1(2,3); // RX, TX
#endif
char ssid[] = "M T G"; // your network SSID (name)
char pass[] = "androidGUII"; // your network password
int status = WL_IDLE_STATUS; // the Wifi radio's status
char server[] = "arduino.cc";
// Initialize the Ethernet client object
WiFiEspClient client;
static const char* host = "api.thingspeak.com";
static const char* apiKey = "xxxxxxxxxxxxxxxxxxxxxxxxxx";
void setup()
{
 // initialize serial for debugging
 Serial.begin(115200);
 // initialize serial for ESP module
 Serial1.begin(9600);
 // initialize ESP module
 WiFi.init(&Serial1);
 // check for the presence of the shield
 if (WiFi.status() == WL_NO_SHIELD) {
 Serial.println("WiFi shield not present");
 // don't continue
 while (true);
 }
 // attempt to connect to WiFi network
 while ( status != WL_CONNECTED) {
 Serial.print("Attempting to connect to WPA SSID: ");
 Serial.println(ssid);
 // Connect to WPA/WPA2 network
 status = WiFi.begin(ssid, pass);
 }
 // you're connected now, so print out the data
 Serial.println("You're connected to the network");
 printWifiStatus();
 Serial.println();
}
void loop()
{
 const int httpPort = 80;
 if (!client.connect(host, httpPort)) {
 Serial.println("connection failed");
 return;
 }
 client.println("GET /channels/xxxxxxx/feeds.json?api_key=xxxxxxxxxx&results=2 HTTP/1.1");
 while (client.available() == 0); // wait till something comes in; you may want to add a timeout here
 Serial.println(client.read());
 client.stop(); // close socket
 delay(10000);
}
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");
}

• Juraj: forum.arduino.cc/index.php?topic=535651
• Wisal Muhammad: dear this is my question which is not answered yet there too..thats' why i posted it here.thank for your time
• gre_gor: @mtg client.read() reads a single byte. I doubt that's what you want.

Answer 1

HTTP GET request needs to end with an empty line and HTTP 1.1 requires a Host header.

Add an empty line and eiher change the HTTP version to 1.0

client.print("GET /channels/421932/feeds.json?api_key=");
client.print(apiKey);
client.println("&results=2 HTTP/1.0");
client.println(); // empty line

or add the Host header

client.print("GET /channels/421932/feeds.json?api_key=");
client.print(apiKey);
client.println("&results=2 HTTP/1.1");
client.print("Host:");
client.println(host);
client.println(); // empty line

• Juraj: the empty line is only for requests with body like POST request, to mark the start of the request body
• gre_gor: @Juraj I tested it in Python by sending it over TCP with only a single pair of "\r\n" and the server didn't respond. Had to be "\r\n\r\n".
• Juraj: I looked up the protocol. It requires the empty line after the header for all requests
• Wisal Muhammad: WiFiEsp] Connecting to api.thingspeak.com 13 [WiFiEsp] Disconnecting 3 //now it shows this in serial monitor
• Juraj: use the library github.com/mathworks/thingspeak-arduino