ESP32 as a Server Handling HTTP GET Requests from a Client

 

ESP32 C-Code used in this video:

// Tinker Foundry

// ESP32 Server to handle GET requests from a client on the local WiFi network

// Indicate request on serial interface and also provide a response to the client

// To test this, once uploaded onto the ESP32, note the IP address reported by ESP32 over the serial monitor, and

// then open a browser on your computer and enter the following in the address bar: http://IP_Address_from_ESP32/?param1=10&param2=hello

// Also, try running the accompanying Python HTTP client code with GUI for a complete experience...

#include <WiFi.h>

// need to install libraries ESPAsyncWebserver and AsyncTCP from Github respository

// https://github.com/me-no-dev/ESPAsyncWebServer

// https://github.com/me-no-dev/AsyncTCP

// In both cases, download library zip files and extract to C:\Users\name\Documents\Arduino\Libraries directory so Arduino will see them

// Remove the "-master" suffix of the library directories

#include "ESPAsyncWebServer.h"

const char* ssid     = "xxxxxxxx";   //input your wifi name

const char* password = "xxxxxxxx";   //input your wifi password

AsyncWebServer server(80);

int cmd_cnt = 0; // this is a counter that we will return as part of data we will return in our responses to client

// Setup function

void setup() {

  pinMode (LED_BUILTIN, OUTPUT); // set built-in LED as output

 

  // standard serial interface setup stuff

  Serial.begin(115200);

  Serial.setDebugOutput(true);

  Serial.println();

  // Setup WiFi...

  WiFi.begin(ssid, password);

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

    delay(500);

    Serial.print(".");

  }

  Serial.println("");

  Serial.println("WiFi connected");

  Serial.print("Msg: Ready! Use 'http://");

  Serial.print(WiFi.localIP());

 

  // Setup route on server by binding it to handling function...

  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){ // use index route "/" and specify we only receive http GET requests

    // Below is handling function...

    int paramsNr = request->params(); // this is number of query parameters sent by client

    Serial.print(paramsNr);

    Serial.println(" parameters received");

 

    // go through and extract the parameters themselves in a loop

    for (int i=0; i<paramsNr; i++)

    {

      AsyncWebParameter* p = request->getParam(i); // retrieve using getParam

      Serial.print("Param name: ");

      Serial.println(p->name());

      Serial.print("Param value: ");

      Serial.println(p->value());

      if (p->name() == "LEDCONTROL")

      {

         if (p->value() == "ON"){

           digitalWrite (LED_BUILTIN, HIGH);

           Serial.println("LED On Command");

        } else if (p->value() == "OFF"){

          digitalWrite (LED_BUILTIN, LOW);

          Serial.println("LED Off Command");

        }

      }

      Serial.print("Command Count: ");

      Serial.println(cmd_cnt);

      Serial.println("-----");

    }

    request->send(200, "text/plain", String(cmd_cnt)); // Return response to client indicating "OK"

    cmd_cnt++;

 

  });

  server.begin();

}

// Main Loop

void loop() {

}

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Python code to implement client with GUI from the video:

# Tinker Foundry Example Python Code

# Python HTTP client to work with ESP32 server using GET requests - this is for the accompanying ESP32 server code meant for this example

# This runs on your local computer, connected on the same WiFi network as your ESP32 controller

# Using simple GUI library for the interface

import PySimpleGUI as sg

# Need the HTTP library - use "pip install requests" if not already installed

import requests

# Using PySimpleGui

sg.theme('SandyBeach') # Window theme

# below are choices for passing parameter types...

param_choices = ('LEDCONTROL', 'Message')

# GUI window layout

layout = [

         [sg.Text('Enter Client Request Details for ESP32 Server')],

         [sg.Text('URL Location', size = (15,1)), sg.Input(expand_x=True, key='urlpath')],

         [sg.Text('Parameter Type', size = (15,1)), sg.Combo(param_choices, size=(15, len(param_choices)), default_value = 'LEDCONTROL', readonly = True, key='param')],

         [sg.Text('Parameter Value', size = (15,1)), sg.Multiline(expand_x=True, expand_y=True, key='value')],

         [sg.Button('Send Request')],

         [sg.HSeparator()],

         [sg.Text('Response output:')],

         [sg.Multiline(expand_x=True, expand_y=True, key='response')],

         [sg.HSeparator()]

]

window = sg.Window('Web Client GUI for ESP32 Server Example', resizable=True).Layout(layout)

while True:  # The Event Loop

    event, values = window.read()

    if event == sg.WIN_CLOSED or event == 'Exit':

        break

    if event == 'Send Request':

        window['response'].print("Submitting request...")

        window['response'].print("")

        URL = values['urlpath'] # url for sending the request to

        PARAMS = {values['param']:values['value']} # parameter and value for the request

        r = requests.get(url = URL, params = PARAMS) # send the GET request

        data = r.content # this is what is returned from the serviced request

        window['response'].print(data) # print out the returned data

        window['response'].print("-------------")

window.close()