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A very practical feature in the IoT field is the ability to program a connected microcontroller, such as an ESP8266, via WiFi. This technique is called Over-The-Air (OTA) Programming.
Hardware
- NodeMCU ESP8266
- USB A Male cable
- Computer
- WiFi network
Operating principle
In principle, the NodeMCU ESP8266 is programmed via the USB port. The computer communicates the program to the microcontroller. When two devices are connected to the same WiFi network, they can communicate with each other. This means that code can be uploaded via the Wifi network without having to connect to each microcontroller.
It is also possible to upload a code to the NodeMCU when it is configured as a Wifi Access Point. In this case, the computer used for programming must be connected to the NodeMCU network.
Add ArduinoOTA firmware
The ArduinoOTA library is available when you install the ESP8266 driver. To enable OTA programming, you need to install the firmware. To do this, you can use the BasicOTA.ino example available in the Arduino IDE.
Be sure to replace ssid and password with your WiFi network credentials.
#include <ESP8266WiFi.h> #include <ESP8266mDNS.h> #include <WiFiUdp.h> #include <ArduinoOTA.h> #ifndef STASSID #define STASSID "your-ssid" #define STAPSK "your-password" #endif const char* ssid = STASSID; const char* password = STAPSK; 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 8266 // ArduinoOTA.setPort(8266); // Hostname defaults to esp8266-[ChipID] // ArduinoOTA.setHostname("myesp8266"); // 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_FS type = "filesystem"; } // NOTE: if updating FS this would be the place to unmount FS using FS.end() Serial.println("Start updating " + type); }); ArduinoOTA.onEnd([]() { Serial.println("\nEnd"); }); ArduinoOTA.onProgress([](unsigned int progress, unsigned int total) { Serial.printf("Progress: %u%%\r", (progress / (total / 100))); }); ArduinoOTA.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(); }
Please note the local IP address of the device (here: 192.168.1.78).
Once this code has been uploaded via serial communication, you will be able to upload code via Wifi. Press the RST or EN button on your ESP and restart the Arduino IDE.
Modify your program before uploading it
We place the initialization code in the initOTA() function. It will then be easy to copy it for other projects. And we’ll add a display on the serial port to check that the code has been modified.
ATTENTION: The ArduinoOTA initialization code must be present in all the code you upload, or you will lose the ability to make aerial transmissions.
#include <ESP8266WiFi.h> #include <ESP8266mDNS.h> #include <WiFiUdp.h> #include <ArduinoOTA.h> const char* ssid = "*******"; const char* password = "********"; unsigned long previousMillis; 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(); } initOTA(); Serial.println("Ready"); Serial.print("IP address: "); Serial.println(WiFi.localIP()); } void loop() { ArduinoOTA.handle(); if (millis() - previousMillis >= 500) { previousMillis = millis(); Serial.println(F("Code has been update")); } } void initOTA() { // Port defaults to 8266 // ArduinoOTA.setPort(8266); // Hostname defaults to esp8266-[ChipID] // ArduinoOTA.setHostname("myesp8266"); // 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_FS type = "filesystem"; } // NOTE: if updating FS this would be the place to unmount FS using FS.end() Serial.println("Start updating " + type); }); ArduinoOTA.onEnd([]() { Serial.println("\nEnd"); }); ArduinoOTA.onProgress([](unsigned int progress, unsigned int total) { Serial.printf("Progress: %u%%\r", (progress / (total / 100))); }); ArduinoOTA.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(); }
Once you have modified your code, under “Tool> Port”, select your card from the network ports. (If the network port is not displayed, see the next section below)
You can then upload your code as you would with serial communication.
Select the serial port again, then open the serial monitor to check that the code has been modified.
If the Network Port is not displayed in the Arduino IDE
If the network port is not present in the Arduino IDE options, you’ll need to perform a little manipulation. Go to the Network and Sharing Center
Then go to “Modify map parameters”.
Right-click on your network, then go to properties
You can then uncheck the “Internet Protocol version 6 (TCP)” option.
If you go back to the Arduino IDE, in ‘Tool > Port’ you should see the network port option.
You can check IPv6 again once your network port is recognized.
Bonus: OTA serial message display
The possibility of uploading a program via WiFi is very welcome, but it’s worth noting that you lose the ability to debug with the serial monitor. A Web interface can be created to display information from the ESP8266 NodeMCU.
Here we’ll be using the RemoteDebug library to telnet to the microcontroller and retrieve the messages sent.
- Start by installing the library by downloading the ZIP file or via the library manager.
- Create a RemoteDebug Debug object; after including the library
- Initialize the debug with Debug.begin(“ESP8266”);
- Then replace all Serial.print with Debug.print
#include <ESP8266WiFi.h> #include <ESP8266mDNS.h> #include <WiFiUdp.h> #include <ArduinoOTA.h> #include <RemoteDebug.h> const char* ssid = "******"; const char* password = "*******"; RemoteDebug Debug; unsigned long previousMillis; 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(); } // init remote debug Debug.begin("ESP8266"); initOTA(); Serial.println("Ready"); Serial.print("IP address: "); Serial.println(WiFi.localIP()); } void loop() { ArduinoOTA.handle(); Debug.handle(); if (millis() - previousMillis >= 500) { previousMillis = millis(); Debug.println(F("Code has been update")); } } void initOTA() { // Port defaults to 8266 // ArduinoOTA.setPort(8266); // Hostname defaults to esp8266-[ChipID] //ArduinoOTA.setHostname("ESP8266"); // 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_FS type = "filesystem"; } // NOTE: if updating FS this would be the place to unmount FS using FS.end() Serial.println("Start updating " + type); }); ArduinoOTA.onEnd([]() { Serial.println("\nEnd"); }); ArduinoOTA.onProgress([](unsigned int progress, unsigned int total) { Serial.printf("Progress: %u%%\r", (progress / (total / 100))); }); ArduinoOTA.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(); }
To view messages sent via RemoteDebug, we’re going to use the PuTTy software we’ve seen several times already. For this application, we’ll configure PuTTy via telnet, using the IP address retrieved from the serial monitor.
