When Arduino Nano is selected in Arduino IDE or the Arduino Web Editor, you will have an additional option to specify the processor on the board. You may need to change this setting if you’re using an older Arduino Nano or a third-party Nano board.

About the processor options

Original Arduino Nano boards use the ATmega328P microcontroller, but those sold in 2018 or later come with an updated bootloader. For this reason, the Arduino AVR Boards package has two versions of ATmega328P available (v1.16.21 and later).

Three processor options are available:

• ATmega328P. Use this for Arduino Nano boards purchased in 2018 or later. This option is selected by default.
• ATmega328P (Old Bootloader). Use this if your Nano was purchased before 2018.
• ATmega168. Used by some third-party Nano boards.

If you don’t know which bootloader or processor is on your board, you can test them one by one by uploading a sketch. If the wrong processor is selected, Arduino IDE will be unable to communicate with the bootloader, and the upload will fail.

Select processor in Arduino IDE

1. In the menu bar, select Tools > Board > Arduino AVR Boards > Arduino Nano.

2. Open the Tools menu again, and find the Processor row. The current selection will be displayed.

3. Put your mouse cursor over the Processor row to reveal the options.

   

4. Click on one of the options to change the selection.

Select processor in the Web Editor

1. Click the “board & port” selection menu.

   

2. Click Select Other Board & Port.

   

3. Under “BOARDS”, make sure Arduino Nano is the selected board.

4. When Arduino Nano is selected, a FLAVOURS selection menu will appear:

   

5. Click on one of the options to change the selection.

6. Click OK to close.