8-pin AVR MCU with 4KB flash. Pin-compatible with ATtiny85.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | PB5/RESET | Reset active low, or I/O | I/O |
| 2 | PB3/ADC3 | Digital I/O, ADC3 | ADC |
| 3 | PB4/ADC2 | Digital I/O, ADC2 | ADC |
| 4 | GND | Ground | GND |
| 5 | PB0/MOSI | SPI MOSI, I2C SDA | BUS |
| 6 | PB1/MISO | SPI MISO, PWM | BUS |
| 7 | PB2/SCK | SPI clock, I2C SCL | BUS |
| 8 | VCC | Supply voltage 2.7–5.5V | PWR |
The ATtiny45 is a pin-compatible sibling of the ATtiny85 with 4KB of flash instead of 8KB. Same 8-pin package, same 6 I/O pins, suitable for very small programs where cost matters.