OTA(Over the Air) 编程是WiFi-enabled 微处理器,比如ESP32或者是ESP8266可以不用物理接触就对固件或者是应用软件进行升级的一种特性。这个特性对一些难以连接电缆的设备重新下载更新程序非常有用。使用OTA,我们可以在同一个网络下对多个微处理器进行升级。例如,这个特性可以被用来向多个微处理器,耳麦,计算机和机顶盒灯发送更新来解决bug,增加新特性。OTA更新在IoT中也扮演很重要的角色。可以通过互联网进行远程更新配置,软件和固件。
前面我们学习过ESP8266 NodeMCU using OTA, 现在我们来学习over-the-air(OTA)为ESP32进行编程。这是通过OTA Web Update in Arduino IDE来实现。
要使用Over the Air(OTA)编程特性,首先是要通过串口来装载一个程序。这个程序包含了HTML代码,保存有OTA更新网页。这样就可以为后来通过浏览器上载程序使用了。将前面说到的程序通过串口上载到ESP32后,会在网络中产生一个web server,这时可以选择通过网页上载一个新程序。
要上载程序前,先要用Arduino IDE连接ESP32板子,选择选择ESP32 Dev Kit。选择正确的串口。
然后,在Arduino IDE中选择File>Example>ArduinoOTA>OTAWebUpdate例子程序。在程序中更改成自己的WiFi名字和密码。
const char* ssid = "Your WiFi Name";
const char* password = "Password";
上载最新的代码到ESP32板子,上载程序后打开串口监视器,按ESP32板子的复位重启按钮,通过串口监视器可以看到这个ESP32服务器的地址。
现在打开默认的浏览器,输入ESP32 IP地址,可以在浏览器中看到下面的画面:
输入用户名和密码,点击login,出现新的画面,如下:
在这里可以更新简单的LED闪耀程序。每个现在的程序中需要又OTA代码。即在OTA代码外增加灯闪烁的程序:
void loop(void)
{
server.handleClient();
delay(1);
digitalWrite(led, HIGH);
delay(600);
digitalWrite(led, LOW);
delay(600);
保存程序。用Sketch>Export compiled Binary。这时在sketch中创建一个.bin的文件。现在,在OTA的web page中选择文件,‘Choose File’ 按钮,选择.bin文件。点击Update按钮。开始上载程序。
下面是不用串口而使用OTA上传程序的代码。
#include
#include
#include
#include
#include
const char* host = "esp32";
const char* ssid = "Galaxy-M20";
const char* password = "ac312129";
//variabls to blink without delay:
const int led = 2;
WebServer server(80);
/*
* Login page
*/
const char* loginIndex =
"
""
""
""
"ESP32 Login Page "
"
"
" "
"
"
"
"
" "
"Username: "
"
"
""
"
"
"
"
""
"Password: "
"
"
"
"
"
"
" "
""
" "
" "
"
"
""
"";
/*
* Server Index Page
*/
const char* serverIndex =
""
"
""
""
""
"progress: 0%"
"";
/*
* setup function
*/
void setup(void) {
pinMode(led, OUTPUT);
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);
digitalWrite(led, HIGH);
delay(600);
digitalWrite(led, LOW);
delay(600);
}
原文
https://circuitdigest.com/microcontroller-projects/esp32-ota-programming-using-arduino-ide