【IoT】如何實現 ESP32 固件的 OTA 在線升級更新

1、背景

在實際產品開發過程中，在線升級可以遠程解決產品軟件開發引入的問題，更好地滿足用戶需求。

2、OTA 簡介

OTA（空中）更新是使用 Wi-Fi 連接而不是串行端口將固件加載到 ESP 模塊的過程。

2.1、ESP32 的 OTA 升級有三種方式：

• Arduino IDE：主要用於軟件開發階段，實現不接線固件燒寫
• Web Browser：通過 Web 瀏覽器手動提供應用程序更新模塊
• HTTP Server：自動使用http服務器 - 針對產品應用 

在三種升級情況下，必須通過串行端口完成第一個固件上傳。 

OTA 進程沒有強加的安全性，需要確保開發人員只能從合法/受信任的來源獲得更新。更新完成後，模塊將重新啓動，並執行新的代碼。開發人員應確保在模塊上運行的應用程序以安全的方式關閉並重新啓動。

2.2、保密性 Security

模塊必須以無線方式顯示，以便通過新的草圖進行更新。 這使得模塊被強行入侵併加載了其他代碼。 爲了減少被黑客入侵的可能性，請考慮使用密碼保護您的上傳，選擇某些OTA端口等。

可以提高安全性的 ArduinoOTA 庫接口：

void setPort(uint16_t port);
void setHostname(const char* hostname);
void setPassword(const char* password);

void onStart(OTA_CALLBACK(fn));
void onEnd(OTA_CALLBACK(fn));
void onProgress(OTA_CALLBACK_PROGRESS(fn));
void onError(OTA_CALLBACK_ERROR (fn));

已經內置了某些保護功能，不需要開發人員進行任何其他編碼。ArduinoOTA和espota.py使用Digest-MD5來驗證上傳。使用MD5校驗和，在ESP端驗證傳輸數據的完整性。

2.2、OTA 升級策略 - 針對 http

ESP32 連接 HTTP 服務器，發送請求 Get 升級固件；每次讀取1KB固件數據，寫入Flash。

ESP32 SPI Flash 內有與升級相關的（至少）四個分區：OTA data、Factory App、OTA_0、OTA_1。其中 FactoryApp 內存有出廠時的默認固件。

首次進行 OTA 升級時，OTA Demo 向 OTA_0 分區燒錄目標固件，並在燒錄完成後，更新 OTA data 分區數據並重啓。

系統重啓時獲取 OTA data 分區數據進行計算，決定此後加載 OTA_0 分區的固件執行（而不是默認的 Factory App 分區內的固件），從而實現升級。

同理，若某次升級後 ESP32 已經在執行 OTA_0 內的固件，此時再升級時 OTA Demo 就會向 OTA_1 分區寫入目標固件。再次啓動後，執行 OTA_1 分區實現升級。以此類推，升級的目標固件始終在 OTA_0、OTA_1 兩個分區之間交互燒錄，不會影響到出廠時的 Factory App 固件。

 

3、OTA 實例解析

3,1、Arduino IDE 方案固件更新

 

從 Arduino IDE 無線上傳模塊適用於以下典型場景： 

在固件開發過程中，通過串行加載更快的替代方案 - 用於更新少量模塊，只有模塊在與 Arduino IDE 的計算機相同的網絡上可用。

參考實例：

#include <WiFi.h>
#include <ESPmDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>

const char* ssid = "..........";
const char* password = "..........";

void setup() {
  Serial.begin(115200);
  Serial.println("Booting");
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.println("Connection Failed! Rebooting...");
    delay(5000);
    ESP.restart();
  }

  // Port defaults to 3232
  // ArduinoOTA.setPort(3232);

  // Hostname defaults to esp3232-[MAC]
  // ArduinoOTA.setHostname("myesp32");

  // No authentication by default
  // ArduinoOTA.setPassword("admin");

  // Password can be set with it's md5 value as well
  // MD5(admin) = 21232f297a57a5a743894a0e4a801fc3
  // ArduinoOTA.setPasswordHash("21232f297a57a5a743894a0e4a801fc3");

  ArduinoOTA
    .onStart([]() {
      String type;
      if (ArduinoOTA.getCommand() == U_FLASH)
        type = "sketch";
      else // U_SPIFFS
        type = "filesystem";

      // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
      Serial.println("Start updating " + type);
    })
    .onEnd([]() {
      Serial.println("\nEnd");
    })
    .onProgress([](unsigned int progress, unsigned int total) {
      Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
    })
    .onError([](ota_error_t error) {
      Serial.printf("Error[%u]: ", error);
      if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
      else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
      else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
      else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
      else if (error == OTA_END_ERROR) Serial.println("End Failed");
    });

  ArduinoOTA.begin();

  Serial.println("Ready");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  ArduinoOTA.handle();
}

3,2、Web Browser 方案固件更新

 

該方案使用場景：

直接從 Arduino IDE 加載是不方便或不可能的

用戶無法從外部更新服務器公開 OTA 的模塊

在設置更新服務器不可行時，將部署後的更新提供給少量模塊

參考實例：

#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <ESPmDNS.h>
#include <Update.h>

const char* host = "esp32";
const char* ssid = "xxx";
const char* password = "xxxx";

WebServer server(80);

/*
 * Login page
 */

const char* loginIndex = 
 "<form name='loginForm'>"
    "<table width='20%' bgcolor='A09F9F' align='center'>"
        "<tr>"
            "<td colspan=2>"
                "<center><font size=4><b>ESP32 Login Page</b></font></center>"
                "<br>"
            "</td>"
            "<br>"
            "<br>"
        "</tr>"
        "<td>Username:</td>"
        "<td><input type='text' size=25 name='userid'><br></td>"
        "</tr>"
        "<br>"
        "<br>"
        "<tr>"
            "<td>Password:</td>"
            "<td><input type='Password' size=25 name='pwd'><br></td>"
            "<br>"
            "<br>"
        "</tr>"
        "<tr>"
            "<td><input type='submit' onclick='check(this.form)' value='Login'></td>"
        "</tr>"
    "</table>"
"</form>"
"<script>"
    "function check(form)"
    "{"
    "if(form.userid.value=='admin' && form.pwd.value=='admin')"
    "{"
    "window.open('/serverIndex')"
    "}"
    "else"
    "{"
    " alert('Error Password or Username')/*displays error message*/"
    "}"
    "}"
"</script>";
 
/*
 * Server Index Page
 */
 
const char* serverIndex = 
"<script src='https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js'></script>"
"<form method='POST' action='#' enctype='multipart/form-data' id='upload_form'>"
   "<input type='file' name='update'>"
        "<input type='submit' value='Update'>"
    "</form>"
 "<div id='prg'>progress: 0%</div>"
 "<script>"
  "$('form').submit(function(e){"
  "e.preventDefault();"
  "var form = $('#upload_form')[0];"
  "var data = new FormData(form);"
  " $.ajax({"
  "url: '/update',"
  "type: 'POST',"
  "data: data,"
  "contentType: false,"
  "processData:false,"
  "xhr: function() {"
  "var xhr = new window.XMLHttpRequest();"
  "xhr.upload.addEventListener('progress', function(evt) {"
  "if (evt.lengthComputable) {"
  "var per = evt.loaded / evt.total;"
  "$('#prg').html('progress: ' + Math.round(per*100) + '%');"
  "}"
  "}, false);"
  "return xhr;"
  "},"
  "success:function(d, s) {"
  "console.log('success!')" 
 "},"
 "error: function (a, b, c) {"
 "}"
 "});"
 "});"
 "</script>";

/*
 * setup function
 */
void setup(void) {
  Serial.begin(115200);

  // Connect to WiFi network
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  /*use mdns for host name resolution*/
  if (!MDNS.begin(host)) { //http://esp32.local
    Serial.println("Error setting up MDNS responder!");
    while (1) {
      delay(1000);
    }
  }
  Serial.println("mDNS responder started");
  /*return index page which is stored in serverIndex */
  server.on("/", HTTP_GET, []() {
    server.sendHeader("Connection", "close");
    server.send(200, "text/html", loginIndex);
  });
  server.on("/serverIndex", HTTP_GET, []() {
    server.sendHeader("Connection", "close");
    server.send(200, "text/html", serverIndex);
  });
  /*handling uploading firmware file */
  server.on("/update", HTTP_POST, []() {
    server.sendHeader("Connection", "close");
    server.send(200, "text/plain", (Update.hasError()) ? "FAIL" : "OK");
    ESP.restart();
  }, []() {
    HTTPUpload& upload = server.upload();
    if (upload.status == UPLOAD_FILE_START) {
      Serial.printf("Update: %s\n", upload.filename.c_str());
      if (!Update.begin(UPDATE_SIZE_UNKNOWN)) { //start with max available size
        Update.printError(Serial);
      }
    } else if (upload.status == UPLOAD_FILE_WRITE) {
      /* flashing firmware to ESP*/
      if (Update.write(upload.buf, upload.currentSize) != upload.currentSize) {
        Update.printError(Serial);
      }
    } else if (upload.status == UPLOAD_FILE_END) {
      if (Update.end(true)) { //true to set the size to the current progress
        Serial.printf("Update Success: %u\nRebooting...\n", upload.totalSize);
      } else {
        Update.printError(Serial);
      }
    }
  });
  server.begin();
}

void loop(void) {
  server.handleClient();
  delay(1);
}

3.3、HTTP 服務器實現更新

 

ESPhttpUpdate 類可以檢查更新並從 HTTP Web 服務器下載二進制文件。可以從網絡或 Internet 上的每個 IP 或域名地址下載更新，主要應用於遠程服務器更新升級。

參考實例：

/**
   AWS S3 OTA Update
   Date: 14th June 2017
   Author: Arvind Ravulavaru <https://github.com/arvindr21>
   Purpose: Perform an OTA update from a bin located in Amazon S3 (HTTP Only)

   Upload:
   Step 1 : Download the sample bin file from the examples folder
   Step 2 : Upload it to your Amazon S3 account, in a bucket of your choice
   Step 3 : Once uploaded, inside S3, select the bin file >> More (button on top of the file list) >> Make Public
   Step 4 : You S3 URL => http://bucket-name.s3.ap-south-1.amazonaws.com/sketch-name.ino.bin
   Step 5 : Build the above URL and fire it either in your browser or curl it `curl -I -v http://bucket-name.ap-south-1.amazonaws.com/sketch-name.ino.bin` to validate the same
   Step 6:  Plug in your SSID, Password, S3 Host and Bin file below

   Build & upload
   Step 1 : Menu > Sketch > Export Compiled Library. The bin file will be saved in the sketch folder (Menu > Sketch > Show Sketch folder)
   Step 2 : Upload bin to S3 and continue the above process

   // Check the bottom of this sketch for sample serial monitor log, during and after successful OTA Update
*/

#include <WiFi.h>
#include <Update.h>

WiFiClient client;

// Variables to validate
// response from S3
int contentLength = 0;
bool isValidContentType = false;

// Your SSID and PSWD that the chip needs
// to connect to
const char* SSID = "YOUR-SSID";
const char* PSWD = "YOUR-SSID-PSWD";

// S3 Bucket Config
String host = "bucket-name.s3.ap-south-1.amazonaws.com"; // Host => bucket-name.s3.region.amazonaws.com
int port = 80; // Non https. For HTTPS 443. As of today, HTTPS doesn't work.
String bin = "/sketch-name.ino.bin"; // bin file name with a slash in front.

// Utility to extract header value from headers
String getHeaderValue(String header, String headerName) {
  return header.substring(strlen(headerName.c_str()));
}

// OTA Logic 
void execOTA() {
  Serial.println("Connecting to: " + String(host));
  // Connect to S3
  if (client.connect(host.c_str(), port)) {
    // Connection Succeed.
    // Fecthing the bin
    Serial.println("Fetching Bin: " + String(bin));

    // Get the contents of the bin file
    client.print(String("GET ") + bin + " HTTP/1.1\r\n" +
                 "Host: " + host + "\r\n" +
                 "Cache-Control: no-cache\r\n" +
                 "Connection: close\r\n\r\n");

    // Check what is being sent
    //    Serial.print(String("GET ") + bin + " HTTP/1.1\r\n" +
    //                 "Host: " + host + "\r\n" +
    //                 "Cache-Control: no-cache\r\n" +
    //                 "Connection: close\r\n\r\n");

    unsigned long timeout = millis();
    while (client.available() == 0) {
      if (millis() - timeout > 5000) {
        Serial.println("Client Timeout !");
        client.stop();
        return;
      }
    }
    // Once the response is available,
    // check stuff

    /*
       Response Structure
        HTTP/1.1 200 OK
        x-amz-id-2: NVKxnU1aIQMmpGKhSwpCBh8y2JPbak18QLIfE+OiUDOos+7UftZKjtCFqrwsGOZRN5Zee0jpTd0=
        x-amz-request-id: 2D56B47560B764EC
        Date: Wed, 14 Jun 2017 03:33:59 GMT
        Last-Modified: Fri, 02 Jun 2017 14:50:11 GMT
        ETag: "d2afebbaaebc38cd669ce36727152af9"
        Accept-Ranges: bytes
        Content-Type: application/octet-stream
        Content-Length: 357280
        Server: AmazonS3
                                   
        {{BIN FILE CONTENTS}}

    */
    while (client.available()) {
      // read line till /n
      String line = client.readStringUntil('\n');
      // remove space, to check if the line is end of headers
      line.trim();

      // if the the line is empty,
      // this is end of headers
      // break the while and feed the
      // remaining `client` to the
      // Update.writeStream();
      if (!line.length()) {
        //headers ended
        break; // and get the OTA started
      }

      // Check if the HTTP Response is 200
      // else break and Exit Update
      if (line.startsWith("HTTP/1.1")) {
        if (line.indexOf("200") < 0) {
          Serial.println("Got a non 200 status code from server. Exiting OTA Update.");
          break;
        }
      }

      // extract headers here
      // Start with content length
      if (line.startsWith("Content-Length: ")) {
        contentLength = atoi((getHeaderValue(line, "Content-Length: ")).c_str());
        Serial.println("Got " + String(contentLength) + " bytes from server");
      }

      // Next, the content type
      if (line.startsWith("Content-Type: ")) {
        String contentType = getHeaderValue(line, "Content-Type: ");
        Serial.println("Got " + contentType + " payload.");
        if (contentType == "application/octet-stream") {
          isValidContentType = true;
        }
      }
    }
  } else {
    // Connect to S3 failed
    // May be try?
    // Probably a choppy network?
    Serial.println("Connection to " + String(host) + " failed. Please check your setup");
    // retry??
    // execOTA();
  }

  // Check what is the contentLength and if content type is `application/octet-stream`
  Serial.println("contentLength : " + String(contentLength) + ", isValidContentType : " + String(isValidContentType));

  // check contentLength and content type
  if (contentLength && isValidContentType) {
    // Check if there is enough to OTA Update
    bool canBegin = Update.begin(contentLength);

    // If yes, begin
    if (canBegin) {
      Serial.println("Begin OTA. This may take 2 - 5 mins to complete. Things might be quite for a while.. Patience!");
      // No activity would appear on the Serial monitor
      // So be patient. This may take 2 - 5mins to complete
      size_t written = Update.writeStream(client);

      if (written == contentLength) {
        Serial.println("Written : " + String(written) + " successfully");
      } else {
        Serial.println("Written only : " + String(written) + "/" + String(contentLength) + ". Retry?" );
        // retry??
        // execOTA();
      }

      if (Update.end()) {
        Serial.println("OTA done!");
        if (Update.isFinished()) {
          Serial.println("Update successfully completed. Rebooting.");
          ESP.restart();
        } else {
          Serial.println("Update not finished? Something went wrong!");
        }
      } else {
        Serial.println("Error Occurred. Error #: " + String(Update.getError()));
      }
    } else {
      // not enough space to begin OTA
      // Understand the partitions and
      // space availability
      Serial.println("Not enough space to begin OTA");
      client.flush();
    }
  } else {
    Serial.println("There was no content in the response");
    client.flush();
  }
}

void setup() {
  //Begin Serial
  Serial.begin(115200);
  delay(10);

  Serial.println("Connecting to " + String(SSID));

  // Connect to provided SSID and PSWD
  WiFi.begin(SSID, PSWD);

  // Wait for connection to establish
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print("."); // Keep the serial monitor lit!
    delay(500);
  }

  // Connection Succeed
  Serial.println("");
  Serial.println("Connected to " + String(SSID));

  // Execute OTA Update
  execOTA();
}

void loop() {
  // chill
}

/*
 * Serial Monitor log for this sketch
 * 
 * If the OTA succeeded, it would load the preference sketch, with a small modification. i.e.
 * Print `OTA Update succeeded!! This is an example sketch : Preferences > StartCounter`
 * And then keeps on restarting every 10 seconds, updating the preferences
 * 
 * 
      rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
      configsip: 0, SPIWP:0x00
      clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
      mode:DIO, clock div:1
      load:0x3fff0008,len:8
      load:0x3fff0010,len:160
      load:0x40078000,len:10632
      load:0x40080000,len:252
      entry 0x40080034
      Connecting to SSID
      ......
      Connected to SSID
      Connecting to: bucket-name.s3.ap-south-1.amazonaws.com
      Fetching Bin: /StartCounter.ino.bin
      Got application/octet-stream payload.
      Got 357280 bytes from server
      contentLength : 357280, isValidContentType : 1
      Begin OTA. This may take 2 - 5 mins to complete. Things might be quite for a while.. Patience!
      Written : 357280 successfully
      OTA done!
      Update successfully completed. Rebooting.
      ets Jun  8 2016 00:22:57
      
      rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
      configsip: 0, SPIWP:0x00
      clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
      mode:DIO, clock div:1
      load:0x3fff0008,len:8
      load:0x3fff0010,len:160
      load:0x40078000,len:10632
      load:0x40080000,len:252
      entry 0x40080034
      
      OTA Update succeeded!! This is an example sketch : Preferences > StartCounter
      Current counter value: 1
      Restarting in 10 seconds...
      E (102534) wifi: esp_wifi_stop 802 wifi is not init
      ets Jun  8 2016 00:22:57
      
      rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
      configsip: 0, SPIWP:0x00
      clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
      mode:DIO, clock div:1
      load:0x3fff0008,len:8
      load:0x3fff0010,len:160
      load:0x40078000,len:10632
      load:0x40080000,len:252
      entry 0x40080034
      
      OTA Update succeeded!! This is an example sketch : Preferences > StartCounter
      Current counter value: 2
      Restarting in 10 seconds...

      ....
 * 
 */

refer：

http://www.yfrobot.com/wiki/index.php?title=OTA_Updates

http://www.yfrobot.com/thread-11979-1-1.html

https://www.arduino.cn/thread-41132-1-1.html

https://blog.csdn.net/abc517789065/article/details/79891568