Arduino Pro Mini 3.3V 8MHz ATmega328P Microcontroller Board

Arduino Pro Mini 3.3V 8MHz – ATmega328P Microcontroller Board

The Arduino Pro Mini 3.3V 8MHz is a compact, low-power microcontroller board based on the ATmega328P, running at 3.3V logic with an 8MHz crystal oscillator. This variant is the go-to choice for battery-powered and low-power embedded applications where 3.3V peripherals (e.g. GPS, GSM, NRF24L01, LoRa, SD cards) need to interface directly without level shifting. No USB interface on-board — programming via an external FTDI 3.3V or CP2102 USB-to-Serial adapter.

Key Features

• Microcontroller: ATmega328P (same core as Arduino Uno)
• Operating Voltage: 3.3V
• Clock Speed: 8MHz crystal oscillator
• 14 digital I/O pins (6 PWM outputs)
• 8 analog input pins (10-bit ADC)
• Flash Memory: 32KB (2KB used by bootloader)
• SRAM: 2KB | EEPROM: 1KB
• Operating current: ~6mA typical (lower than 5V variant)
• Input voltage: 3.3V via VCC pin or 3.35V–9V via RAW pin (on-board regulator)
• Ultra-compact: 33mm × 18mm PCB
• Castellated / through-hole edge pads for direct PCB integration

Pin Highlights

• Digital Pins: D0–D13 (D0/D1 = UART TX/RX)
• Analog Pins: A0–A7
• PWM Pins: D3, D5, D6, D9, D10, D11
• SPI: D10 (SS), D11 (MOSI), D12 (MISO), D13 (SCK)
• I2C: A4 (SDA), A5 (SCL)
• Programming Header: DTR, RX, TX, VCC, GND, GND (FTDI 3.3V compatible)

Typical Applications

• Battery-powered sensor nodes and data loggers
• 3.3V peripheral interfacing (GPS, GSM, NRF24L01, LoRa, SD card) without level shifting
• Wearable electronics and ultra-compact embedded systems
• Low-power IoT edge nodes with sleep modes
• Direct PCB integration via castellated pads

3.3V vs 5V Variant – Which to Choose?

• Use 3.3V / 8MHz when running on batteries, interfacing with 3.3V-only modules, or minimizing power consumption
• Use 5V / 16MHz when maximum processing speed is needed or working with 5V peripherals

Programming

Requires a 3.3V FTDI or CP2102 USB-to-Serial adapter — do NOT use a 5V adapter as it will damage the board. In the Arduino IDE, select "Arduino Pro or Pro Mini" → ATmega328P (3.3V, 8MHz).