Introducing the Modified Pico

After a lot of behind the scenes work and various prototypes and revisions, I figure the Grounding Open Source Hardware conference at the Banff New Media Institute in Alberta, Canada this week is as good a time as any to announce the Modified Pico. The Pico is a smaller, low power, Freeduino variant using the Atmel ATmega328 and is fully Arduino Duemilanove compatible. It is similar to the Arduino Nano but is made using simpler fabrication methods to make it smaller and less expensive and is available as a semi-kit allowing much more freedom in its application. It also ships standard with the new ATmega328 microcontroller that doubles the available memory of the former 168. The Pico does not include an on-board voltage regulator instead using the power from USB or allowing for low power external input (from 3-5 VDC) such as 3 AA battery packs and 5V regulated switching power supplies. Its features include:

ATmega328 running at 16MHz with external resonator (0.5% tolerance)
On-board FTDI232 USB to Serial Connection
Supports auto-reset (choose Duemilanove w/ ATmega328 in the Arduino? software)
Operating voltage of 2.7 - 5.5 VDC
Schottky diode reverse polarity protection (very low drop-out)
Auto-sense power input between USB and external source
Resettable 500 mA fuse for overcurrent protection
On-board pin 13 and communication LEDs

For more information, images, schematic, and production files, please see the Modified Electronics website and blog. We are now selling our first (small) batch of these boards beginning today and will endeaver to ramp up production as demand increases in the upcoming weeks. I need to thank my wife Susan Porteous for all of her hard work on the new website and, above all else, the Pico could not have been possible without the support of the OSH community so thank you. If you have any thoughts please let us know.

Brian Evans
Modified Electronics

Great effort Brian. As a "competitor" with the smallest Arduino Duemilanove compatible device (om328p), I understand what it takes to bring something like this together. The "pico" is only a fraction of an inch smaller than the Nano. The om328p is 0.2" shorter at 1.4" by 0.7"

Personally I prefer the "stamp" style layout for TX/RX/Vin/Gnd/Reset/5V but understand you made some compromises in this area. Also it would be good if the A6/A7 pins were at minimum aligned with the other pins and best if they could also be used with a breadboard. It would take some shifting around but I know it all fits having a similar board layout using the SOIC version of the FTDI chip that is 1.5" long.

The pico is missing a regulator but does bring out the AREF input. I understand that most people will power it from USB but a regulator is nice for stand-alone use.

Your website mentions that the Pico can be used from 2.7V to 5V. This is not correct when using a 16MHz crystal. The ATmega328p is only rated down to 3.6V @ 16MHz. Also the FTDI chip needs a minimum of 4V to operate.

Great work. $25 is certainly a good price point. Very cool, and it looks elegant as well. Not that it's a big deal, but it is nicer to use elegant stuff.

Did you create this in Eagle? I'm interested in creating a board using Eagle, and was wondering if you have to buy a full license of Eagle to sell it. Do you know? (I'm hoping the answer is no).

BTW, I noticed that the "tutorials" link on your website's "modified pico" page does not appear to go anywhere.

Mike while your design is smaller it does sacrifice a lot of usability without a silkscreen layer to help identifying pins. And while I recognize the Pico is only a fraction of an inch smaller it could be argued that your om328p is also only a fraction of an inch smaller.

A couple other design notes and responses... Im not really interested in legacy compatibility with the Basic Stamp. I think for today's users and the types of things I see artists, designers, and students doing, legacy support is more of a hindrance. The Pico features all digital i/os on one side with the analog and comms on another. This mimics the simplicity of the original Arduino design.

Ive also talked about the intent of low power applications... it seems inefficient to me to have a v-reg on-board and hook up a 9v source just to turn that into heat for no good reason. I think its easy enough just to hook up a 5 volt source when not using USB or just use this on battery power. And if youre using battery you should have access to Aref just to make sure analog readings are on the up and up.

The extra analog pins are precisely that... extra. For the few times someone might need them they can easily hook up pin headers of one form or another. I did not want a situation where a user might accidentally hook up the two extra analog pins to pin A0 by plugging it into a breadboard. Ill put together a tutorial at some point showing a few ways of using those extra ADCs.

The Pico has been in development for over 14 months so its pretty cool to see it out there now. Thanks for the comments and keep them coming!


Edit: Mike I also noticed you have a non-commercial clause on your om328p... this goes against the Arduino Creative Commons Attribution-Share Alike license. You should reconsider as this seems to be in violation of making derivative works based on the Arduino design.

We have differing views on what is important and that is one of the virtues of competition. Let me correct some of the statements in your append.

The om328p has the pin numbers on the bottom of the PCB. This is not a complete silkscreen of pin functionality but the board is quite packed with components. The complete User Guide and Reference provides a pinout guide as does this picture.

AREF is connected to VCC on the om328p. In this case you always have the highest possible range. Most of the time a variable AREF isn't required and if a value lower than VCC is needed then you can use the internal AREF of 1.2V.

The om328p board was designed first of all as a follow on to existing Oak Micros ZBasic devices. See our website for all of the other devices we offer. The ZBasic ZX-328nu was released before the om328p and is a breadboard version of other ZBasic mega328p based devices such as the ZX-328n. That is why for example the om328p contains two additional active low LEDs. It was a very easy and minor change to add a SCK yellow LED for Arduino compatibility.

The schematic for the om328p is generally available both in the User Guide and Reference and as an Eagle schematic. As stated in the Oak Micros readme, the BRD file is available on request and is intended for non-commercial use. I do not use Arduino in the name of my product and I am not in violation of any licensing. In fact the Arduino team saw my design before it was published but decided not to make it an official Arduino.

I've enjoyed the dialog between both you developers. I think that we the customers and community members get the biggest advantage of having both open source based system and competitive vendors showing their stuff and ideas.

As I said I've enjoy reading the comments as long as there is no zippers pulling down, who's bigger (or in some cases, who's smaller :wink: ) arguments.

Good stuff


Lefty is correct, the advantage of open source hardware is the inherent diversity and dialog of the projects.

As for Aref, connecting this to VCC is all well and good but having access to it is invaluable if you are running from the 5v of usb but using a 3v sensor and need to calibrate it. Another one of those features similar to the extra ADC pins - they can be used when needed or ignored otherwise.

As to the CC-BY-SA license this does not apply to the name Arduino (that would be the trademark) but instead the design of the board itself. So if you make a derivative work of the Arduino hardware, as the Pico and I believe your om328p is, these works should adhere to the terms described in the CC liscense found here.


When I saw this I fell in love with it! Ordered one for me and my friend.


But, one question. How do you run it with only battery power? Just use a 5volt regulator on 5+ and gnd?

Thanks for the comments. 3 AA batteries connected to the +5v and Gnd pins would do it. Ill work up a tutorial on this in the next couple of weeks if I get the chance.


Where do you guys ship from? And any idea how long it will take to arrive in Norway?

Just can't wait :smiley:

Stigern, we ship from Denver, Colorado, US. I honestly don't know how long it will take as we are new to all this. My wife is doing the shipping while Im away this week but I know it's shipped. Let me know when you get it.

Here's a cool image of some workshop participants assembling Picos yesterday. There's more info on the blog.

With over a dozen ATMega's running on various boards the last thing I need is to buy another Arduino. And yet, I love that board! :smiley:
It looks great and I want one. Maybe I'll walk over to your house and buy one. :wink:

My Pico arrived today in my mailbox. What a lovely little arduino :smiley:

Thats great! Only a week to Norway isn't too bad. I wonder how consistent that will be. Enjoy the Pico!


Mine shipped today as well.. but i have a small problem. no matter what i do i get a

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

The board Settings are at Duemilanove w. 328 as well as the right port chosen... is there something else i have to keep in mind with the pico i just havent seen yet? Oh btw - its blinking in a 1se interval - so i guess blink is uploaded and working ;0) -only uploading my own stuff wont work ><

Anyway - that thing looks great and is exactly what i needed!