How to upload a program on a arduino pro mini

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Arduino pro mini board is a miniatural board perfect for permanent projects. It runs on atmega328 and atmega168 at 3.3 and 5 Volts and 8 or 16Mhz.

The maximum current on each pin is 40mA but the entire current on the board must not exceed 200mA.Arduino pro mini can’t be programmed through an usb port because it hasn’t one on board.  This device can be programmed with two methods, one with an usb-to-ttl adapter or with another arduino(for example uno).

This device is perfect on projects with small vibrations(you can solder pins direct to a pcb-i used it on car project), or with a small space avaible.

An arduino pro mini is presented below:

arduino pro mini

1: usb-to-ttl adapter

To upload a program to arduino pro mini we have used a CP2102 usb-to-ttl serial converter.

The converter is in the image below:

usb-to-ttl converter

This converter has 6 pins where:

DTR-is used for board reset(some models of converters do not have this pin and you must do the reset manually from the pro mini button-before to buy check if it has )

RXD-receiver pin

TXD-transmmiter pin

5V-Vcc for 5 Volts boards

3v3-Vcc for 3.3Volts boards

Next to connect the board with the converter i have soldered some pins like in the image:

pro mini pins

Now connect all the pins:


TX0-TX0(in some cases you must connect TX0 on the converter with the RX0 on the board and RX0 to TX0 )


Vcc-to 5V or 3V3(depend on the board)


pro mini converter usb

After these connection connect the converter to the usb.


In arduino software we must choose the port from Tools/Port, Tools/Board-Arduino Pro or Pro Mini and Tools/Proccessor(here you choose your model) then upload and should work.

A short video with blink program at different speed is below:

2. Using an arduino uno(only for pro mini 5V 16Mhz)

Again you must solder pins like in the previous example and connect them to arduino uno

DTR-to RESET pin on arduino

TX0-TX0 on arduino(pin 1)

RX0-Rx0 on arduino(pin 0)

VCC-5 V to arduino

GND-GND to arduino


In the software keep the same settings like for the converter example.

A short video:


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