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How to Install ATTinyCore on Arduino IDE

In order to program an ATtiny microcontroller in Arduino IDE, we need to install the ATTinyCore Arduino core. The ATTinycore was written by Spence Konde. It supports almost the whole family of ATtiny AVR microcontrollers. The following ATtiny microcontrollers are supported:

  • ATtiny1634
  • ATtiny2313/4313
  • ATtiny24/44/84
  • ATtiny441/841
  • ATtiny25/45/85
  • ATtiny261/461/861
  • ATtiny87/167
  • ATtiny48/88
  • ATTiny43
  • ATtiny828

Additionally, the ATTinyCore supports programming via ICSP AVR programmers, Serial (Optiboot), and VUSB (Micronucleus).

1. Install the Arduino IDE

If you don’t have the Arduino IDE (Integrated Development Environment) yet, you can download it here. As of this writing, the latest stable version is 1.8.19.

Screenshot of the website where Arduino IDE can be downloaded and subsequently installed and loaded with ATTinyCore for programming ATtiny MCUs
Arduino IDE Download Page

2. Add the ATTinyCore URL to the Board Manager

Open the Arduino IDE and on the main menu, select Files -> Preferences. In the Additional Boards Manager URLs textbox, type the URL ““, and then press the OK button.

Screenshot of Arduino IDE showing the File/Preferences setting for installing the ATtinyCore by Spence Konde
Arduino IDE with the File –> Preferences Settings

If the textbox already contains additional URLs, press the button on the right side of the textbox. A window will appear where you can type the URL on a new line.

Screenshot of Arduino IDE showing the different board URLs installed including the ATtinyCore
Additional Boards Manager URLs Window

3. Install the Board

On the main menu, select Tools -> Board -> Board Manager.

Screenshot of Arduino IDE showing the Board Manager for installing the ATtinyCore boards
Arduino IDE Showing the Board Manager Menu

When the Board Manager window appears, change the board Type from All to Contributed (1). Next, find and select the ATTinyCore board (2). Then, click the Install button (3). And finally, close the Board Manager window by clicking the Close button (4).

Screenshot of an annotated Arduino IDE Board Manager showing the steps for installing ATtiny boards
Annotated Arduino IDE Board Manager Window

Select the Board

From the main menu, open Tools –> Board –> ATTinyCore and then select the appropriate ATtiny board for your microcontroller.

Note that in selecting a board, you will have to choose among No bootloader, Optiboot, and Micronucleus. First, choose No bootloader if you are programming with an AVR programmer. Second, select Optiboot if your ATtiny MCU has been previously burned with an Optiboot bootloader and it is wired as an Optiboot serial device. Finally, select Micronucleus if the MCU has been flushed with a Micronucleus bootloader and connected as a USB device. For more information about these three (3) programming modes, please see How to Program ATtiny85 in Arduino IDE.

Screenshot of Arduino IDE showing the list of boards supported by the installed ATTinyCore Arduino core
Arduino IDE Showing the List of ATTinyCore Supported Boards

The next and final step depends on your chosen programming mode. If you select No bootloader, then you will need to choose a programmer. Open Tools –> Programmer and select the AVR programmer you are going to use. You may also have to specify the Port if your AVR programmer uses the serial port. Although most AVR programmers like the USBasp and USBtinyISP are USB devices and you won’t have to specify the port.

Screenshot of Arduino IDE showing the list of AVR programmers supported by the ATTinyCore
Arduino IDE Showing the List of ATTinyCore Supported AVR Programmers

If you choose Optiboot, you need to specify the serial port. Open Tools –> Port and select the port for your ATtiny microcontroller.

Screenshot of Arduino IDE showing how to select the serial port
Arduino IDE Showing Port Selection

Finally, if you choose Micronucleus, you also don’t have to specify the port because Micronucleus uses a virtual USB device.

Now, you’re ready to start programming your ATtiny microcontroller!

References on How to Install ATTinyCore on Arduino IDE

How to Install Arduino IDE on Windows 10
How to Program ATtiny85 with Arduino IDE
Digispark USB Device Not Recognized
ATTinyCore – ATtiny Arduino core by Spence Konde

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