Arduino Pro Mini Pinout

Arduino Pro Mini is the smallest classic Arduino, with an ATmega328P chip (33 × 18 mm). It has no USB or converter – sketches are uploaded through the six-pin FTDI header with an external USB-serial converter. That keeps power consumption low, which makes it a good fit for battery projects.

It comes in 5 V / 16 MHz and 3.3 V / 8 MHz versions.

Specifications

ATmega328P: 8-bit AVR, 16 MHz (5 V version) or 8 MHz (3.3 V version)
32 kB flash, 2 kB SRAM, 1 kB EEPROM
14 digital pins (6× PWM), 8 analog inputs (A6 and A7 analog only)
UART, I2C (A4/A5 pads) and SPI (D10–D13)
no USB – upload with a USB-serial converter via the FTDI header
power via RAW (up to 12 V) or VCC
33 × 18 mm

To upload, connect a converter with a DTR pin (FTDI, CP2102, CH340) to the FTDI header: GND, VCC, RXI to the converter’s TX, TXO to RX, and DTR. The board resets itself before uploading. For low power draw on batteries, the power LED and the regulator are usually disconnected (solder jumper SJ1).

Pinout and pin table

Hover over a pin in the diagram or a table row; use the filter to highlight a bus. You can download the pinout as PNG or SVG.

Pin names:

FTDI and inner pads

Download:PNG SVG

Download – FTDI and inner pads:PNG SVG

License: CC BY 4.0 · How to credit

Pin table – Arduino Pro Mini
Name	Chip port	Direction	UART	I2C	SPI	PWM	ADC	Note
D0	PD0	input/output	RX					UART RX, RXI on the silkscreen – connect the converter's TX
D1	PD1	input/output	TX					UART TX, TXO on the silkscreen – connect to RX of the converter
D2	PD2	input/output						External interrupt INT0
D3	PD3	input/output				PWM		External interrupt INT1; PWM from Timer 2 (OC2B)
D4	PD4	input/output
D5	PD5	input/output				PWM		PWM from timer 0 (OC0B)
D6	PD6	input/output				PWM		PWM from timer 0 (OC0A)
D7	PD7	input/output
D8	PB0	input/output
D9	PB1	input/output				PWM		PWM from timer 1 (OC1A)
D10	PB2	input/output			SS	PWM		PWM from timer 1 (OC1B); SPI SS
D11	PB3	input/output			MOSI	PWM		PWM from timer 2 (OC2A); SPI MOSI
D12	PB4	input/output			MISO			SPI MISO
D13	PB5	input/output			SCK			SPI SCK; onboard LED
A0	PC0	input/output					ADC0
A1	PC1	input/output					ADC1
A2	PC2	input/output					ADC2
A3	PC3	input/output					ADC3
A4	PC4	input/output		SDA			ADC4	I2C SDA (Wire) – inner pad on the board
A5	PC5	input/output		SCL			ADC5	I2C SCL (Wire) – inner pad on the board
A6		input					ADC6	Analog input only – inner pad on the board
A7		input					ADC7	Analog input only – inner pad on the board
RST		input						Reset – connecting to GND restarts the chip
GND		–
VCC		input/output						Regulated board voltage – 5 V on the 16 MHz version, 3.3 V on the 8 MHz version. It can power the board from a regulated supply; cutting solder jumper SJ1 next to the regulator disconnects both the regulator and the power LED (low power).
RST		input						Reset – connecting to GND restarts the chip
GND		–
RAW		input						Unregulated power input to the MIC5205 regulator (max. 150 mA). Per the manufacturer 5–12 V (5 V version) and 3.35–12 V (3.3 V version); for a stable output it is better to have at least 1 V above VCC.
GND		–
GND		–
VCC		input/output						Regulated board voltage – 5 V on the 16 MHz version, 3.3 V on the 8 MHz version. It can power the board from a regulated supply; cutting solder jumper SJ1 next to the regulator disconnects both the regulator and the power LED (low power).
RXI		input						FTDI: same as D0 (UART RX)
TXO		output						FTDI: same as D1 (UART TX)
DTR		input						FTDI: resets the chip through a 0.1 µF capacitor before upload

What to watch out for

The converter voltage must match the board version – don’t power the 3.3 V version from 5 V.
I2C is on the A4 (SDA) and A5 (SCL) pads inside the board, not on the edge headers.
A6 and A7 are analog inputs only.
Clones often have the A4–A7 and GND pads in different places, and some use the ATmega328PB – check the silkscreen on your board.
The regulator supplies only 150 mA.