How to Program ATtiny85 Using Arduino IDE: Step-by-Step Guide

To program an ATtiny85 using the Arduino IDE, first install the ATtiny board support via the Board Manager, then connect the ATtiny85 to your Arduino as an ISP programmer. Finally, select the ATtiny85 board and programmer in the IDE and upload your sketch.

Syntax

Programming the ATtiny85 with Arduino IDE involves these main steps:

• Install Board Support: Add ATtiny85 boards via the Board Manager.
• Connect Hardware: Use an Arduino as ISP to connect to the ATtiny85 pins.
• Select Board: Choose ATtiny85 and clock speed in the Tools menu.
• Select Programmer: Choose Arduino as ISP.
• Upload Sketch: Use Upload Using Programmer to flash the code.

text

1. Open Arduino IDE
2. Go to File > Preferences
3. Add URL to Additional Boards Manager URLs:
   https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json
4. Open Tools > Board > Boards Manager
5. Search 'attiny' and install
6. Connect Arduino as ISP to ATtiny85
7. Select Tools > Board > ATtiny25/45/85
8. Select Tools > Processor > ATtiny85
9. Select Tools > Clock > 8 MHz (internal)
10. Select Tools > Programmer > Arduino as ISP
11. Upload your sketch using Sketch > Upload Using Programmer

Example

This example blinks the onboard LED connected to pin 0 of the ATtiny85 every second. It shows how to write and upload a simple sketch.

arduino

void setup() {
  pinMode(0, OUTPUT); // Set pin 0 as output
}

void loop() {
  digitalWrite(0, HIGH); // LED on
  delay(1000);           // Wait 1 second
  digitalWrite(0, LOW);  // LED off
  delay(1000);           // Wait 1 second
}

Output

The LED connected to pin 0 blinks on and off every second.

Common Pitfalls

• Wrong Wiring: Make sure Arduino pins connect correctly to ATtiny85 pins for ISP programming.
• Incorrect Board Selection: Select the exact ATtiny85 board and clock speed in the IDE.
• Using Upload Instead of Upload Using Programmer: Always use Upload Using Programmer to flash the ATtiny85.
• Missing Bootloader Burn: Burn the bootloader once to set fuses before programming.

arduino

/* Wrong way: Using normal Upload button */
// This will fail because ATtiny85 needs programmer upload

/* Right way: Use Upload Using Programmer */
// In Arduino IDE, choose Sketch > Upload Using Programmer

Quick Reference

Step	Action	Details
1	Install Board Support	Add ATtiny URL in Preferences and install via Boards Manager
2	Connect Hardware	Wire Arduino as ISP to ATtiny85 pins (MISO, MOSI, SCK, RESET, VCC, GND)
3	Select Board	Choose ATtiny85 and clock speed (usually 8 MHz internal)
4	Select Programmer	Choose Arduino as ISP in Tools > Programmer
5	Burn Bootloader	Burn bootloader once to set fuses (Tools > Burn Bootloader)
6	Upload Sketch	Use Sketch > Upload Using Programmer to flash code

Key Takeaways

Install ATtiny85 board support via Arduino IDE Boards Manager before programming.

Use an Arduino as ISP programmer and connect it correctly to the ATtiny85 pins.

Select the correct board, processor, clock, and programmer settings in the Arduino IDE.

Burn the bootloader once to set ATtiny85 fuses before uploading sketches.

Always use 'Upload Using Programmer' to flash code to the ATtiny85.