attiny85 tutorials

Program ATtiny85 using Arduino IDE: Burn Bootloader, Board installation and LED Blink Example


Program ATtiny85 using Arduino IDE: Burn Bootloader, Board installation and LED Blink Example- The ATtiny85 microcontroller, a tiny yet powerful member of Atmel’s AVR series, is popular among enthusiasts for its simplicity and flexibility in small-scale projects. Programming it using the Arduino IDE makes it accessible to a broader audience. This comprehensive guide will walk you through burning the bootloader onto an ATtiny85, installing the board in the Arduino IDE, and creating a basic LED blink example.

Why Burn a Bootloader?

Before we dive into the step-by-step process, let’s quickly discuss why burning a bootloader is important. The ATtiny85 is a powerful microcontroller, but by default, it lacks a bootloader. A bootloader is a small piece of software that allows you to easily upload code to the microcontroller without the need for specialized hardware.

By burning a bootloader onto your ATtiny85, you can take advantage of the convenience and flexibility provided by the Arduino IDE. This means you can write and upload code to your ATtiny85 just like you would with any other Arduino board.

What You’ll Need

Before we get started, make sure you have the following items:

ATtiny85 microcontroller

Arduino Uno or another Arduino board

Jumper wires

USB cable




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Step 1: Setting Up the Arduino IDE

If you haven’t already, download and install the latest version of the Arduino IDE from the official Arduino website. Once installed, open the Arduino IDE.

Step2: upload the ArduinoISP code:

Click on File in the menu bar at the top of the IDE. Hover over Examples to open the Examples submenu. Scroll down and find 11.ArduinoISP. Click on ArduinoISP to open the ArduinoISP sketch.

Program ATtiny85 using Arduino IDE

Make sure to select the following settings for uploading the ArduinoISP code.

Program ATtiny85 using Arduino IDE

After setting it, upload it to the Arduino board by clicking the ‘Upload’ button.

Program ATtiny85 using Arduino IDE

As you can see the code is successfully uploaded.

Program ATtiny85 using Arduino IDE

Step 3: Connection for ATtiny85 Arduino Bootloader:

To burn the bootloader onto the ATtiny85, we’ll need to connect it to an Arduino board. Follow the circuit diagram:

Program ATtiny85 using Arduino IDE

Pin 10 of Arduino to Reset (Pin 1) of ATtiny85 (Green Wire): The Arduino uses this connection to reset the ATtiny85, initiating the bootloader for programming.

Pin 11 of Arduino to MOSI (Pin 5) of ATtiny85 (Yellow Wire): MOSI (Master Out Slave In) is the line through which the Arduino sends data to the ATtiny85.

Pin 12 of Arduino to MISO (Pin 6) of ATtiny85 (Blue Wire):  MISO (Master In Slave Out) is used by the ATtiny85 to send data back to the Arduino.

Pin 13 of Arduino to SCK (Pin 7) of ATtiny85 (Pink Wire):  SCK (Serial Clock) synchronizes data transmission between the Arduino and the ATtiny85.

5V of Arduino to VCC (Pin 8) of ATtiny85: It provides the necessary power to the ATtiny85.

GND of Arduino to GND (Pin 4) of ATtiny85: This connection provides a common ground reference.

This setup is typically used when the Arduino is loaded with the “Arduino as ISP” sketch, enabling it to act as an In-System Programmer to program the ATtiny85 or to burn a bootloader onto it. After setting up this circuit, you would use the Arduino IDE to burn the bootloader or upload sketches to the ATtiny85, selecting “Arduino as ISP” as the programmer in the Tools menu.

ATtiny85 Board Installation:

To install the ATtiny85 board in the Arduino IDE, you’ll need to add the board to the Arduino board manager. This process allows the Arduino IDE to understand the configuration and programming protocol of the ATtiny85. Here’s a step-by-step guide:

Open Arduino IDE: Launch your Arduino IDE on your computer.

Access Preferences: Go to the File menu and select Preferences (On macOS, it’s under Arduino in the menu bar).

Program ATtiny85 using Arduino IDE

Add Board Manager URL:

In the Preferences window, find the field named “Additional Board Manager URLs.”

You need to add the URL for the ATtiny board manager. This URL can vary depending on the source, but a commonly used one is the

If there are already URLs in this field, separate them with a comma and paste the new URL at the end.

Program ATtiny85 using Arduino IDE

Open Board Manager:

Go to Tools > Board > Boards Manager…

Program ATtiny85 using Arduino IDE

The Boards Manager will open in a new window.

In the Boards Manager, type “ATtiny” in the search bar.

Program ATtiny85 using Arduino IDE

You will see one or more entries for ATtiny boards. For example, “Attiny” by David A. Mellis might appear.

Click on the entry and then click the Install button to install the package. As you can our package is installed.

Program ATtiny85 using Arduino IDE

Selecting the ATtiny85 Board:

After installation, go to Tools > Board and scroll down to find the ATtiny series of boards.

Select the specific ATtiny board you are using (e.g., ATtiny25/45/85).

Program ATtiny85 using Arduino IDE

After selecting the ATtiny board, additional options will appear in the Tools menu for setting the processor, clock, etc.

Make sure to select ATtiny85 under Processor and choose the appropriate clock setting based on your setup.

Program ATtiny85 using Arduino IDE

Then click on the burn Bootloader,

Program ATtiny85 using Arduino IDE

and wait for a moment to burn the ATtiny85:

Program ATtiny85 using Arduino IDE

As you can the “done burning bootloader “.

We have successfully installed everything; now, let’s create a very simple blink application.

ATtiny85 Led Blink Example using Arduino:

In this project, we’ll explore how to program the ATtiny85 using the familiar Arduino IDE to perform a basic yet fundamental task – blinking an LED. This simple example not only introduces you to the basics of microcontroller programming and circuitry but also lays the groundwork for more complex projects in the future.

Code uploading Attiny85 circuit diagram:

Every time you want to upload code to the ATtiny85 using an Arduino, you will need the following circuit diagram.

Program ATtiny85 using Arduino IDE

The circuit diagram explained above is used to upload the LED blink code to the ATtiny85. Once the code is successfully uploaded, remove the extra wire from the ATtiny85 and then connect the LED directly to it. The specific circuit diagram for the LED blink setup is provided below.

ATtiny85 led blink Program:

ATtiny85 led blink Circuit diagram:

Program ATtiny85 using Arduino IDE

This connection is used solely to power up the ATtiny85. If you have a 5V power supply, simply connect the power supply’s ground to the ATtiny85’s ground, and the positive to pin 8 of the ATtiny85.

Practical Demonstration:


Installing the ATtiny85 board package in the Arduino IDE is the first step towards programming this powerful microcontroller. Once installed, you can unleash your creativity and build a wide range of projects using the ATtiny85 and the Arduino IDE.

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