ATtiny85 Micro-USB Digispark Compatible Mini Development Board

ATtiny85 Micro-USB Digispark Compatible Mini Development Board is an ultra-compact 8-bit AVR microcontroller development board powered by the Microchip/Atmel ATtiny85 MCU and equipped with a standard female Micro-USB Type-B receptacle. Furthermore, it runs the Micronucleus USB bootloader at 16.5 MHz and includes an onboard 78M05 5V 500mA voltage regulator, allowing seamless programming from the Arduino IDE over a standard Micro-USB data cable. Therefore, it eliminates the loose port fit of PCB-tab USB dongles while providing 6 versatile GPIO pins with PWM, 10-bit ADC, I2C, and SPI capabilities.

Key Features:

• Reliable Micro-USB Female Receptacle: Connects via any standard Micro-USB data cable so the board can sit flat on a breadboard or inside an enclosure without hanging off a laptop USB port.
• Arduino IDE & Digispark Ecosystem Compatible: Flashes directly over USB via the built-in Micronucleus V-USB bootloader with zero external programmer hardware required.
• Onboard 5V 500mA Voltage Regulator: Accepts 7V–12V DC unregulated power on the `VIN` pin for standalone battery or wall-adapter operation.
• 6 Multifunction I/O Pins (P0–P5): Offers 3 PWM outputs, 4 channels of 10-bit analog-to-digital conversion, and USI I2C/SPI serial buses.
• Built-In Power & User Test LEDs: Includes a power indicator LED plus a programmable status LED wired to `P1 (PB1)`.

Technical Specifications:

• Microcontroller: Microchip / Atmel ATtiny85-20SU (8-Bit AVR RISC MCU)
• Operating Clock: 16.5 MHz Internal PLL (Synchronized during USB Communication)
• Flash Memory: 8 KB Total (~6 KB Usable after Micronucleus Bootloader)
• SRAM & EEPROM: 512 Bytes SRAM | 512 Bytes EEPROM
• Supply Voltage: 5.0V DC via Micro-USB or `5V` Pin | 7V–12V DC via `VIN` Pin
• GPIO Pins: 6 Digital I/O Pins (`P0–P5`)
• PWM Outputs: 3 Channels (`P0, P1, P4`)
• ADC Inputs: 4 × 10-Bit Analog Inputs (`P2, P3, P4, P5`)
• USB Connector: Micro-USB Type-B Female Port

Mechanical Specifications:

• PCB Construction: Double-Sided Blue/Black FR-4 Fiberglass PCB
• Header Layout: 1 × 6-Pin GPIO Header (`P0–P5`) + 1 × 3-Pin Power Header (`5V, GND, VIN`) at 2.54mm Pitch
• USB Shielding: Surface-Mount Metal Micro-USB Socket with Through-Hole Anchor Tabs

Dimensions:

• Length: 22.0 mm
• Width: 18.0 mm
• Height: 4.5 mm (Unpinned)
• Weight: ≈ 3.2 g

Pinout and Wiring:

• 5V / GND / VIN Header: Supply 7V–12V DC to `VIN` for regulated 5V operation, or take 5V output from `5V` when powered over Micro-USB.
• P0 (PB0 / SDA / MOSI / PWM): Primary I2C data line and hardware PWM output.
• P1 (PB1 / MISO / PWM / LED): Connected to the onboard user LED and hardware PWM timer.
• P2 (PB2 / SCL / SCK / ADC1 / INT0): Primary I2C clock line, external interrupt, and analog input 1.
• P3 (PB3 / ADC3 / USB-) & P4 (PB4 / ADC2 / PWM / USB+): Shared with the Micro-USB data lines via 68Ω series resistors and a 1.5kΩ pull-up on P3.
• P5 (PB5 / ADC0 / RESET): Analog input 0 / weak digital I/O.
• Engineering Precaution: Disconnect external heavy loads or pull-down circuits from `P3` and `P4` while uploading code over Micro-USB, as loading those two pins will prevent the PC from enumerating the V-USB bootloader.

Datasheet Reference:

• View Official Microchip ATtiny25/45/85 Microcontroller Datasheet PDF

Commonly Used in:

• Breadboard ATtiny85 Prototyping & Compact Embedded Control Loops
• Custom USB HID Media Knobs, Foot Pedals, and Stream Macro Buttons
• Addressable WS2812B LED Strip Controllers and Miniature Sensor Nodes

Applications:

• Enclosure-Mounted USB Peripherals: Mounts cleanly inside small 3D-printed project boxes with a panel-accessible Micro-USB port.
• I2C Sensor + SSD1306 OLED Mini Display: Uses `TinyWireM` and `Tiny4kOLED` libraries on `P0 (SDA)` and `P2 (SCL)` to drive a 128×64 OLED screen from an 8-pin MCU.
• Low-Cost Watchdog & Power Sequencer: Monitors main system heartbeats and toggles MOSFET or relay power rails.

Equivalent Models:

• ATtiny85 Digispark Direct USB-A Development Board: Uses an integrated PCB Male USB-A plug instead of a female Micro-USB socket.
• ATtiny13A/25/45/85 Development Programmer Board: Breakout/programmer board with an 8-pin DIP socket and Micro-USB power for swapping bare DIP-8 ATtiny chips.
• LGT8F328P Mini EVB / Arduino Pro Mini: Full 32KB 8-bit boards with 20+ GPIOs when your project outgrows 6 I/O pins.

Package Includes:

• 1 × ATtiny85 Micro-USB Digispark Compatible Mini Development Board