Digispark ATtiny85 USB Development Board

The Digispark ATtiny85 USB Development Board is a tiny, low-cost microcontroller board that plugs straight into a USB port and programs from the Arduino IDE. Built around the ATtiny85, it's ideal for small projects where a full Arduino is overkill, such as USB keyboard and HID devices, LED controllers, simple sensors, and compact embedded builds.

The board has a Micro USB connector for programming and power, an onboard 5V regulator for external supplies, and 6 I/O pins with PWM, ADC, I2C and SPI support. It comes preloaded with the Micronucleus USB bootloader, so no separate programmer is needed.

Features

• ATtiny85 8-bit AVR microcontroller
• Programs directly over Micro USB with the Arduino IDE
• Powered by USB, 5V, or an external 6V to 16V supply via VIN
• Onboard 5V regulator
• 6 I/O pins (2 shared with USB)
• PWM on 3 pins, ADC on 4 pins
• I2C and SPI via the USI peripheral
• Power LED and onboard status LED
• USB protection diodes

Specifications

• Microcontroller: ATtiny85
• Flash memory: 8KB (about 6KB available after bootloader)
• SRAM: 512 bytes
• EEPROM: 512 bytes
• Clock speed: 16.5MHz
• Operating voltage: 5V
• USB power: 5V via Micro USB
• External power (VIN): 6V to 16V
• I/O pins: 6
• PWM pins: 3
• ADC: 10-bit, 4 channels
• Interfaces: I2C, SPI (via USI)

Pinout

• P0: PWM, I2C SDA, SPI MOSI
• P1: PWM, SPI MISO
• P2: ADC1, I2C SCL, SPI SCK
• P3: ADC3, USB D+ (has a 1.5k pull-up resistor)
• P4: PWM, ADC2, USB D-
• P5: ADC0, Reset (limited use as I/O)
• 5V: 5V output from the regulator, or 5V input
• GND: Ground
• VIN: External power input, 6V to 16V

The onboard status LED is connected to P1 on most boards, or P0 on some revisions.

Getting Started

• Install the Digistump AVR board package in the Arduino IDE using the Boards Manager.
• Windows users will need to install the Digistump drivers for the board to be recognised.
• Click Upload first, then plug the board in when prompted. The bootloader only accepts uploads for a few seconds after connection.

Usage Notes

• The board waits about 5 seconds on power-up for the bootloader before running your sketch.
• P3 and P4 are used for USB communication. They can be used as normal I/O, but external circuits on these pins can stop the board from uploading.
• P5 is the reset pin and is best used as an analog input only.
• With only 512 bytes of SRAM, large libraries and serial-heavy sketches may not fit. For bigger projects, consider an Arduino Nano or ESP32.

Documentation

• ATtiny85 Datasheet (PDF)