This library allows you to update sketches on your board over WiFi or Ethernet.

The library is a modification of the Arduino WiFi101OTA library.

• Supported micro-controllers
• Supported networking libraries
• Installation
• OTA Upload from IDE without 'network port'
• OTA update as download
• ATmega support
• ESP8266 and ESP32 support
• nRF5 support
• Arduino 'network port'
• Troubleshooting
• Boards tested

• classic ATmega AVR with at least 64 kB of flash (Arduino Mega, MegaCore MCUs, MightyCore 1284p and 644)
• Arduino SAMD boards like Zero, M0, MKR and Nano 33 IoT
• Arduino Uno R4 boards
• nRF5 board supported by nRF5 core.
• RP2040 boards with Pico core
• STM32F boards with STM32 core
• boards supported by ESP8266 and ESP32 Arduino boards package
• any board with MCU with SD bootloader
• any board with custom Storage and boot-load solution for that storage
• Nano RP2040 Connect with mbed core with custom storage example and SFU library

The ArduinoOTA library will work any proper Arduino Ethernet or WiFi library. For Ethernet library add #define OTETHERNET before including the ArduinoOTA library. If you don't want a network port or the library doesn't support it, add #define NO_OTA_PORT before including the ArduinoOTA library. If you only want to use InternalStorage without the network upload from IDE, add #define NO_OTA_NETWORK before including the ArduinoOTA library.

Tested libraries are:

• Ethernet library - Ethernet shields and modules with Wiznet 5100, 5200 and 5500 chips
• WiFi101 - MKR 1000, Arduino WiFi101 shield and Adafruit WINC1500 WiFi shield or module
• WiFiNINA - MKR 1010, MKR 4000, Nano 33 IoT and any supported MCU with attached ESP32 as SPI network adapter with WiFiNINA firmware
• WiFiS3 library of Arduino Uno R4 WiFi
• WiFiEspAT - esp8266 or ESP32 as network adapter with AT firmware
• EthernetENC - shields and modules with ENC28j60 chip
• WiFi library of the Pico Core including its Ethernet network interfaces

EthernetENC and WiFiEspAT doesn't support UDP multicast for MDNS, so Arduino IDE will not show the network upload port.

The library is in Library Manager of the Arduino IDE.

Note for platformio users: Please, don't use this library with platformio. It was not tested with platformio and most of the documentation doesn't apply.

Arduino SAMD boards (Zero, M0, MKR, Nano 33 IoT) are supported 'out of the box'. Additionally to upload over the internal flash as temporary storage, upload over SD card and over MEM shield's flash is possible. For upload over SD card use the SDU library as shown in the WiFi101_SD_OTA or similar for upload over MKR MEM shield use the SFU library.

For Uno R4, RP2040, nRF5 and STM32 boards, platform.local.txt from extras folder has to be copied into boards package installation folder. For nRF5 details scroll down. For RP2040 the bundled ArduinoOTA library must be deleted.

For ESP8266 and ESP32 boards, platform.local.txt from extras folder has to be copied into boards package installation folder and the bundled ArduinoOTA library must be deleted. For details scroll down.

ATmega boards require to flash a modified Optiboot bootloader for flash write operations. Details are below.

For other MCU upload over SD card is possible if the MCU has SD bootloader which can bootload the update bin from SD card. See the ATmega-SD example. Some MCU can use a second stage SD bootloader linked to the sketch as a library similar to SAMD package's SDU library.

With InternalStorage the sketch binary size is limited to half of the available flash memory size. The available flash size may be reduced by the bootloader and EEPROM emulation space.

For upload the 'OTA programmer' technique can be configured.

The upload tool in IDE gas a timeout 10 seconds. For some sketch size, MCU or library it is too short. To set longer timeout, download newer version of the tool, replace the 1.3.0 arduinoOTA executable and in platform.local.txt add the -t option in seconds.

Some networking libraries don't have the UDP.beginMulticast function and can't start a MDNS service to propagate the network port for Arduino IDE. And sometimes the MDNS port is not detected for the good libraries too. Arduino IDE doesn't yet allow to enter the IP address.

The workaround is to configure a fake programmer for Arduino OTA. You can use my_boards as starting point. For Arduino Mega it is the best option for all ArduinoOTA aspects, for other boards it gives you control about your custom settings. In your copy of my_boards in programmers.txt, configure the IP address and restart the IDE. Note: the esp boards packages can't be used as referenced packages in my_boards style.

If you don't want to use my_boards, the platform.local.txt files for avr and samd in extras folder in this library contain the configuration for arduinoOTA tool as programmer. Copy platform.local.txt next to platform.txt in the hardware package of your board. The programmers.txt file can't have a 'local' extension so you have to add your OTA 'programmer' configuration into the existing programmers.txt file. Then restart the IDE.

Example OTA 'programmer' configuration in programmers.txt:

arduinoOTA104.name=Arduino OTA (192.168.1.104)
arduinoOTA104.program.tool=arduinoOTA
arduinoOTA104.program.tool.default=arduinoOTA
arduinoOTA104.ip=192.168.1.104

In IDE select in Tools menu the "Arduino OTA (...)" programmer and use "Upload using programmer" from the Sketch menu in IDE.

Important! If you test OTA with the 'fake' programmer, close the Serial Monitor in IDE. With Serial Monitor open, IDE will reset the board after upload tool finishes. The board then doesn't finish to apply the update.

Note: For Arduino MKR WiFi 1010 and Arduino Nano 33 IoT the SNU library and storage support in the nina firmware can be used for OTA update as download. See the SNU library example in the IDE Examples menu.

Note: Don't use this for esp8266 and esp32 Arduino. Use the ESP8266httpUpdate and the esp32 HTTPUpdate library for OTA update download for esp8266/esp32. Or use the Update object from esp8266 core of the Update library directly.

The WiFi101OTA and ArduinoOTA libraries were created for upload from IDE. But in some scenarios as for example deployed sleeping battery powered devices it is better to have the update available for download by the device.

In advanced section of examples you can find examples of sketch update over download from a http server. One example shows update over the InternalStorage object of the ArduinoOTA library. The example for update over SD card doesn't use this library at all.

The Blynk library uses this library in its Blynk.Edgent examples to store and apply user's updated sketch downloaded from the Blynk IoT cloud storage.

The sizes of networking library and the SD library allows the use of ArduinoOTA library only with ATmega MCUs with at least 64 kB flash memory.

Side note: There are other network upload options for here excluded ATmega328p: (Ariadne bootloader for Wiznet chips, WiFiLink firmware for the esp8266) or AvrDudeTelnet upload (Linux only).

For upload with ArduinoOTA library over InternalStorage, Optiboot bootloader with copy_flash_pages function is required. MegaCore and MightyCore by MCUDude before version 3 has Optiboot binaries with copy_flash_pages function ready to be burn to your ATmega.

The most common Arduino ATmega board with more than 64 kB of flash memory is Arduino Mega. To use it with ArduinoOTA library, you can't use it directly with the Arduino AVR package, because the package doesn't have the right fuse settings for Mega with Optiboot. You can download my boards definitions and use it to burn the modified Optiboot and to upload sketches to your Mega over USB and over network.

For SDStorage a 'SD bootloader' is required to load the uploaded file from the SD card. The SDStorage was tested with zevero/avr_boot. Note that the zevero/avr_boot doesn't support USB upload of sketch. The ATmega_SD example shows how to use this ArduinoOTA library with SD bootloader.

To use remote upload from IDE with SDStorage or InternalStorage, copy platform.local.txt from extras/avr folder, next to platform.txt in the boards package used (Arduino-avr or MCUdude packages).

The IDE upload tool is installed with Arduino AVR core package. At least version 1.2 of the arduinoOTA tool is required. For upload from command line without IDE see the command template in extras/avr/platform.local.txt.

This library allows to upload a sketch to esp8266 or esp32 over Ethernet with Ethernet or EthernetENC library.

Both esp8266 and esp32 Arduino core now support wired network as additional network interface for their networking (STA and SoftAP are the 'built-in' network interfaces). With their Ethernet libraries you can use the standard OTA upload of the esp8266 and esp32 platform with wired network.

With esp8266 platform's lwIP_xy libraries (optionally with the EtherCompat.h) you can use W5500, W5100 and ENC28J60 wired network.

With esp32 platform version 3 you can use the EthernetESP32 library (available in Library Manager) with a variety of Ethernet modules including W5500 and ENC28J60. See the BasicOTA example in the EthernetESP32 library,

To use this library instead of the bundled library, the bundled library must be removed from the boards package library folder. To override the configuration of OTA upload in platform.txt, copy the platform.local.txt file from extras folder of this library next to platform.txt file in boards package installation folder. For Arduino IDE 2 use platform.local.txt from extras/IDE2.

This library supports SPIFFS upload to esp8266 and esp32, but the IDE plugins have the network upload tool hardcoded to espota. It can't be changed in configuration. To upload SPIFFS, call the plugin in Tools menu and after it fails to upload over network, go to location of the created bin file and upload the file with arduinoOTA tool from command line. The location of the file is printed in the IDE console window. Upload command example (linux):

~/arduino-1.8.8/hardware/tools/avr/bin/arduinoOTA -address 192.168.1.107 -port 65280 -username arduino -password password -sketch OTEthernet.spiffs.bin -upload /data -b

(the same command can be used to upload the sketch binary, only use -upload /sketch)

For SD card update use SDUnRF5 library.

To use remote upload from IDE with SDStorage or InternalStorage, copy platform.local.txt from extras/nRF5 folder, next to platform.txt in the nRF5 boards package.

If SoftDevice is not used, the sketch is written from address 0. For write to address 0 the sketch must be compiled with -fno-delete-null-pointer-checks. The setting is in extras/nRF5/platform.local.txt.

If you use SoftDevice, stop BLE before applying update. Use ArduinoOTA.beforeApply to register a callback function. For example in setup ArduinoOTA.beforeApply(shutdown); and add the function to to sketch:

void shutdown() {
  blePeripheral.end();
}

The Arduino IDE detects the Arduino 'network port' using mDNS system. This requires the use of UDP multicast. From networking libraries supported for OTA upload only Ethernet, WiFiNina and WiFi101 libraries support multicast. For these libraries ArduinoOTA.h at defaults starts the mDNS service.

In some networks or on some computers UDP mDNS doesn't work. You can still use the ArduinoOTA library for upload from command line or with the fake programmer trick described elsewhere in this README.

It is possible to suppress use of the mDNS service by the library. Only define NO_OTA_PORT before the include like this:

 #define NO_OTA_PORT
 #include <ArduinoOTA.h>

To see the details of upload command in IDE, set verbose mode for upload in IDE Preferences. arduinoOTA tool version should be 1.2 or higher.

• undefined reference to `InternalStorage' - make sure you selected a board supported by the ArduinoOTA library
• 'ArduinoOTA' was not declared in this scope - make sure a networking library is included before the ArduinoOTA.h include

Not with all supported networking libraries this library can propagate a 'network port'. See the list in 'Supported networking libraries' section of this page.

For networking libraries which support mDNS, sometimes the OS blocks or can't handle mDNS required to discover the 'network port'. Sometimes it helps to wait a little, sometimes it helps to restart the IDE, sometimes it helps disconnect and connect the network on the computer.

You have still the option to use a 'fake programmer' as described in "OTA Upload from IDE without 'network port'".

The password doesn't match. Password is the third parameter in ArduinOTA begin() in sketch.

In platform.local.txt files in extras folder the password is configured as variable parameter for the normal OTA upload. The IDE asks for password and supplies the variable's value. The examples expect password "password".

platform.txt in my_boards and the fake programmer tool definition in platform.local.txt have the password set as "password" to match the examples.

The wrong upload command from AVR boards platform.txt is used. Did you copy extras/avr/platform.local.txt next to platform.txt as required?

If upload fails with Flashing sketch ... Error flashing the sketch after 10 seconds, the problem is the 10 seconds timeout of IDE's upload tool.

To set longer timeout, download newer version of the tool, replace the 1.3.0 arduinoOTA executable and in platform.local.txt add the -t option in seconds.

The final loading of the uploaded binary is in some cases not under control of the ArduinoOTA library.

For SD card way the SD bootloader or the SDU library is responsible for loading the new binary. So SD bootloader must be present and in case of SDU, the uploaded sketch must contain the SDU library. Note that other SPI devices may disturb access to the SD card from the bootloader/SDU. Make sure there are pull-up resistors on the CS pins.

For AVR InternalStorage upload the final loading is done by the Optiboot with copy_flash_pages function. Optiboot 8 without copy_flash_pages will successfully store the binary to upper half of the flash but will not copy it to run location in flash.

If you test OTA with the 'fake' programmer, close the Serial Monitor in IDE. With Serial Monitor open, IDE will reset the board after upload tool finishes. The board then doesn't finish to apply the update.

Does the OTA uploaded sketch have ArduinoOTA?

• SAMD21
  • Arduino MKR Zero
  • Crowduino M0 SD
  • Arduino Nano 33 IoT
  • Arduino MKR WiFi 1000
  • Arduino MKR WiFi 1010
  • Adafruit Feather M0 Express
• SAMD51
  • Seeed Wio Terminal (with Blynk.Edgent)
• Renesas core
  • Uno R4 WiFi
• RP2040
  • Raspberry Pi Pico
  • Arduino RP2040 Connect
• STM32
  • BluePill F103CB (128kB flash)
  • BlackPill F411CE
  • NUCLEO-F303RE
• nRF5
  • Seeed Arch Link (nRF51 board)
  • nrf52832 board
• ATmega
  • Arduino Mega
  • Badio 1284p
• esp8266
  • Wemos D1 mini
• esp32
  • ESP32 Dev Module