What Is the ATtiny85? 8-Pin AVR: Pinout, Specs and Uses
October 11, 2026 5 min read
Quick answer
The ATtiny85 is a small 8-pin 8-bit AVR microcontroller. With 8 KB flash, 512 B SRAM, 6 GPIO (PB0–PB5), an ADC and PWM, it is ideal for small, cheap, low-power projects. It can be programmed with the Arduino IDE (with the right core); it has no hardware UART.
The ATtiny85 is a small 8-pin 8-bit AVR microcontroller. Despite its size it includes an ADC, PWM and timers; it is ideal for small, low-cost, low-power projects. For the concept, see what is a microcontroller (MCU).
What is the ATtiny85 used for?
Small embedded tasks that do one job: LED effects, small sensor reads, PWM for a motor/servo, wearable projects. It can be programmed with the Arduino IDE (with the right core installed).
ATtiny85 pinout (DIP-8)
| Pin | Function |
|---|---|
| 1 | PB5 / RESET |
| 2 | PB3 (ADC3, XTAL1) |
| 3 | PB4 (ADC2, XTAL2) |
| 4 | GND |
| 5 | PB0 (MOSI, SDA, PWM) |
| 6 | PB1 (MISO, PWM) |
| 7 | PB2 (SCK, SCL, ADC1) |
| 8 | VCC |
Highlights
| Parameter | Value |
|---|---|
| Core | 8-bit AVR |
| Flash / SRAM / EEPROM | 8 KB / 512 B / 512 B |
| GPIO | 6 (PB0–PB5) |
| Clock | up to 20 MHz, internal 8 MHz RC |
| Supply | 1.8 – 5.5 V |
Limitations
- Only 6 GPIO and 512 B RAM; for larger projects use the ATmega328P.
- No hardware UART (software serial is used).
- Turning the RESET pin into a GPIO complicates programming (needs a high-voltage programmer).
Equivalents and alternatives
- ATtiny13: smaller/cheaper.
- ATtiny45: the half-flash sibling.
- ATtiny84: 14-pin, more GPIO.
- ATmega328P: for larger projects.
Find it in our catalog
Use the ATtiny85 search.
Frequently Asked Questions
What is the ATtiny85?+
The ATtiny85 is a small 8-pin 8-bit AVR microcontroller. With 8 KB flash, 512 B SRAM, 6 GPIO, an ADC and PWM it is ideal for small, cheap, low-power projects.
What is the ATtiny85 pinout?+
DIP-8: 1 PB5/RESET, 2 PB3, 3 PB4, 4 GND, 5 PB0 (MOSI/SDA), 6 PB1 (MISO), 7 PB2 (SCK/SCL), 8 VCC.
Can the ATtiny85 be programmed with Arduino?+
Yes, with the right core (e.g. ATTinyCore) installed it can be programmed from the Arduino IDE; it is usually flashed using an Arduino as an ISP programmer.
How many GPIO does the ATtiny85 have?+
It has 6 GPIO (PB0–PB5); the ADC, PWM and I2C/SPI hardware are shared across these pins. There is no hardware UART.
What is an equivalent to the ATtiny85?+
The smaller ATtiny13/ATtiny45; the ATtiny84 for more pins; and the ATmega328P for larger projects.