How To Program a Meduino Pro Mini using an Arduino Uno as usb-serial adapter

This image shows how to wire Arduino Uno and Meduino Pro mini in order to ulpoad sketches to Meduino pro mini using Arduino uno as USB-Serial Adapter
Arduino Uno as Serial port for Meduino Pro Mini

This little article covers the steps needed in order to use an arduino Uno board as USB-Serial adapter for Meduino Pro Mini, another well done Arduclone.

Well i want to avoid an USB-FTDI serial adapter in order to upload sketches to my Meduino Pro Mini.
It is a good cheap ebay-ish Ardu-clone, in fact it has a 3-5 Volts Switch, that, compared to the Arduino Pro Mini, avoids a couple of pins, thus SDA and SCL are no more “hidden” but exposed and well wired, much more comfortable. On the other side the Arduino Mini Pro (used this other article for a Multiwii project from scratches) can deliver both 3 and 5 Volts simultaneously and also has more leds (tx and rx are missing from Meduino Pro Mini).

It misses also the USB port and, consequently, the onboard adapter too. So If you don’t want to buy an FTDI USB-Serial adapter (like me) and want to use your other arduino model with an USB port, just remove the microprocessor from the Arduino Uno, and then connect the following pins as described:

Arduino Uno 5V -> Meduino Pro Mini Vin
Arduino Uno GND -> Meduino GND
Arduino Uno Pin0 (RX0) -> Meduino Pro Mini Pin1 (RX1)
Arduino Uno Pin1 (TX1) -> Meduino Pro Mini Pin0 (RX0)
Arduino Uno Reset -> Meduino Pro Mini RST

This way, the Arduino Uno will act as usb-serial adapter for Meduino pro mini.

In this pic i used a mini breadbord to put things together and save some space.

This image shows how to wire Arduino Uno and Meduino Pro mini in order to ulpoad sketches to Meduino pro mini using Arduino uno as USB-Serial Adapter
Arduino Uno as Serial port for Meduino Pro Mini

Using The IDE

To upload sketches with the Arduino IDE, just attach your sandwich to your pc with the usb cable, open uo the ide and select your model from the drop down, in this case our model is not listed, for this reason we will choose:
“Arduino Pro or Pro Mini (5V, 16Mhz) w/ ATmega328”.

That’s all.

p.s. You can try with a simple sketch like the blink (the Meduino Pro Mini blinks on Pin13 with no need to add a led). 

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Author: Giuseppe Urso

Giuseppe lives in Haarlem now with his shiny dog, Filippa In 1982 received his first home computer, a Commodore 64, followed by Datasette and a 1541 Floppy Disk Drive. In 1999 he installed his first Linux distro (LRH6). In 2006 he switched to Debian as favourite OS. Giuseppe Urso actively sustains the Free Software Fundation and his founder Richard Mattew Stallman, he speaks to people trying to convince them to join the fight now, and about how important is to use Free Software only. He has a job as Infra Specialist at Hippo Enterprise Java Cms an Open Source Enterprise class Content Management System, one of the coolest company ever, in Amsterdam. He's always ready to install Debian on other people computers for free.

4 thoughts on “How To Program a Meduino Pro Mini using an Arduino Uno as usb-serial adapter”

  1. Hi,
    Just wondering, does this work with the latest Uno (the one without the FTDI chip?)
    they are using another atmega chip now for the USB-Serial interface.


    1. Well you tell me something new, dude.
      But i’ve searched some info and i found that :

      One improvement in updating the chip is that, previously, Mac users needed to install FTDI drivers. The 8u2 imitates a ‘generic’ CDC serial device. So now, Mac users do not have to install a driver. Windows users still need to install the .INF file but luckily there are no drivers. This means there will be fewer problems with new versions of windows. There is no way to have a serial USB device that doesn’t require an INF file in windows, sadly 🙁

      The big thing that is nice about the 8u2 is that advanced users can turn it into a different kind of USB device. For example it can act like a keyboard or mouse. Or a disk driver. Or a MIDI interface, etc. Right now there are no examples of how to do this, but we hope to post some shortly.

      And, finally, going with the 8u2 reduced the price of the board which made up for some of the other extras.

      So this is all good!!! it was just what i was wondering and also, it can be flashed.


      There’s a new bootloader. It works just like the old one – being an STK500-protocol compatible but its a quarter of the size! Down from 2K, the new bootloader is a tiny 512b. This gives you more space for your project code! Yay! It’s also faster – 115K instead of 57.6k so you’ll be uploading code in 3 seconds.

      The Bad News is that you must make sure to select Uno in the Boards menu!!! If you don’t things will be confusing because the bootloader speed is wrong, and you won’t get that extra 1.5K!

      Overall, its a good direction, and the chips can be used in older Arduinos just fine (so you can upgrade your Diecimila or Duemilanove to the Uno by simply replacing the chip).

      I’ want a new Arduino Uno!!!!!

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