README.md

OTA_Blink

This is a project dedicated to making the simplest program that can make OTA (Over The Air) with an esp8266 and a server programmed in php. OTA means that the device can be updated via WiFi.

I did the project because at least for me the examples of the ESP8266httpUpdate library did not work.

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The project has two sides:

• Arduino Sketch
• Server

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Arduino sketch:

libraries used:

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <ESP8266HTTPClient.h>
#include <ESP8266httpUpdate.h>

WiFi configuration

//your ssid
#define ssid "yourSsid"
//your password
#define pass "yourPassword"

OTA configuration

//you have to use your server url
#define OTAHost "http://192.168.1.48/firmware/index.php"
//the name of the compiled arduino sketch
#define Version "OTA_Blink.ino.nodemcu.bin"

The following is optional and depends on how you decide to build your code, if it updates every certain time this may work for you.

//the time between updates expressed in milliseconds
#define OTAPeriodicity 10000

The function that updates

void OTA()

The Sample code (blink)

  //An easy blink
  digitalWrite(2, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);             // wait for a second
  digitalWrite(2, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);             // wait for a second

And the update logic

  //The update
  static unsigned long t;
  if (millis() > t) {
    t = millis() + OTAPeriodicity;
    OTA();
  }

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Server

Basic checks

The server does some checks to confirm that the device that is requesting the sketch is adequate:

if(
    $_SERVER['HTTP_USER_AGENT'] != 'ESP8266-http-Update' ||
    !isset($_SERVER['HTTP_X_ESP8266_STA_MAC']) ||
    !isset($_SERVER['HTTP_X_ESP8266_VERSION']) ||
    !isset($_SERVER['HTTP_X_ESP8266_FREE_SPACE']) ||
    !isset($_SERVER['HTTP_X_ESP8266_SKETCH_MD5'])
) {
    header($_SERVER["SERVER_PROTOCOL"].' 403 Forbidden', true, 403);
    echo "only for ESP8266 updater! (header)\n";
    exit();
}

Memory check

A check to see if the device has enough memory

$path = "bin/".$_SERVER['HTTP_X_ESP8266_VERSION'];
if($_SERVER['HTTP_X_ESP8266_FREE_SPACE'] < filesize($path)) {
    header($_SERVER["SERVER_PROTOCOL"].' -100 too less space', true, -100);
    exit();
}

note: the compiled sketches have to be in the same folder as the .php file

Modification check

And a check to see if the sketch that the device already has installed is the latest version of it.

if($_SERVER['HTTP_X_ESP8266_SKETCH_MD5'] == md5_file($path)) {
    header($_SERVER["SERVER_PROTOCOL"].' 304 Not Modified', true, 304);
    exit();
}

This is done with the MD5 code.

The sending the compiled sketch

header($_SERVER["SERVER_PROTOCOL"].' 200 OK', true, 200);
header('Content-Type: application/octet-stream', true);
header('Content-Disposition: attachment; filename='.basename($path));
header('Content-Length: '.filesize($path), true);
header('x-MD5: '.md5_file($path), true);
readfile($path);

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