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title: Arduino Pro Mini description: Minimalist ATmega328P board with no USB and no DC jack. Two variants: 5 V/16 MHz and 3.3 V/8 MHz. Flash it with an external USB-TTL adapter (CP2102, FT232,...


microcontrollers / arduino-pro-mini.md

Arduino Pro Mini

Minimalist ATmega328P board with no USB and no DC jack. Two variants: 5 V/16 MHz and 3.3 V/8 MHz. Flash it with an external USB-TTL adapter (CP2102, FT232, CH340).

In stock CC-BY-SA-3.0 1 files · 613 KB

Specs

Spec 5 V version 3.3 V version
MCU ATmega328P ATmega328P
Clock 16 MHz 8 MHz
Operating voltage 5 V 3.3 V
Input voltage (RAW) 5–12 V 3.35–12 V
Digital I/O 14 (6 PWM) 14 (6 PWM)
Analog inputs 6 + 2 internal 6 + 2 internal
Flash / SRAM / EEPROM 32 KB / 2 KB / 1 KB 32 KB / 2 KB / 1 KB

Programming pinout (FTDI header)

[GND] [GND] [VCC] [RX] [TX] [DTR]

Wire to USB-TTL adapter:

Pro Mini USB-TTL
GND GND
VCC VCC (match voltage!)
RXI TX
TXO RX
DTR DTR

Voltage match

Use a USB-TTL with selectable 3.3 V/5 V output. Feeding 5 V to a 3.3 V Pro Mini's VCC can fry it.

When to pick Pro Mini

  • Battery / wearables (drop the USB chip, save current)
  • Compact PCB footprint
  • Already have a USB-TTL programmer

Schematic

Open schematic (PDF)

Last updated: 2026-05-13 · Source on GitHub