Instructables
This board needs FTDI cable to program it.

It is not Arduino compatible in the meaning of taking shields (just like every small form factor board isn't).

But it has all the same pins (exept 3.3V power and Vin*) available as female headers. The input and output pins that are right next to each other on original Arduino, almost are the same here, except digital 4 and 5. That means the order is:
RESET	0	1	2	3	4	VCC	GND	_	_	5	6	7	8
9	10	11	12	13	VCC	AREF	GND	A0	A1	A2	A3	A4	A5


It has power indication LED. Not an essential part, but it reminds you to remove the battery when not in use and I have also found it to be useful to notice shorts in my circuit – the power LED goes dim in that case.

It does not have 13th pin LED.

* - Mine has only 9V battery clip directly soldered to it, but this is the easiest part to modify. It also does not have ICSP header, but in the rare case a ISP programmer would be needed it is possible to access all these pins through female headers or remove the Atmega from socket.




So what's the purpose of such thing? I felt I needed a secondary controller besides my usual Arduino for testing things out. I missed that when programming my robot for a contest where IR transmitters were supposed to indicate important places and my attempt to make ATtinys do similar transmission failed. And now I have a task of learning about radio modules ahead of me and I want a familiar platform to test them out before trying to also mess with microcontrollers new to me that are supposed to go into the final product.

When considering the price remember these aspects:
  • Do you already have FTDI cable or for how much can you purchase it? (I managed to make one myself, but it takes precise etching and SMD soldering. Also the needed chip is not super cheap for experimentation. Further details http://www.instructables.com/id/FTDI-cable/ )
  • Do you have an Arduino (in working order) or AVR programmer to use for burning bootloader on a blank ATmega or can you get the controller with bootloader for reasonable price?


If all that described suits you and you feel ready to do some tightly packed soldering – it really wasn't too easy to get all wires to their right spot – then here is my documentation of the project.
 
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schel9 months ago

Much Thanks!!!...I'm doin' it!

mitakskia1 year ago
If you need even smaller - http://www.geocities.jp/Arduino_diecimila/obaka/project-2/index_en.html
really good and informative tutorial, i have one question in my mind, now, can i use all pins as if it is being used from Arduino board ? or any special care like adding cap or resisters or crystals etc to be added to use pins like input pin and output pin ?
Libahunt (author)  arduino-tester1 year ago
If I understand your question correct then the answers is - the board can be used just the same as a factory made Arduino board, exept one thing. I have seen tutorials that allow you to connect a LED directly, without resistor, to pin 13. This is because a factory made Arduino has a built in LED there and they claim that it's current limiting resistor is for some reason in series with the pin header. My design does not have it. You may destroy your LED doing that. Here is a schematic for home-madeable board from official Arduino site http://arduino.cc/en/uploads/Main/ArduinoSeverinoSchematic.png - this one actually has the resistor in parallel but there is no circuitry between the rest of the input/output pins and their pin headers.

Slightly offtopic, there may arise some issues that your circuit components on pins 0 and 1 (TX and RX) may interfere while programming or with using serial connection commands, but this is exactly the same with factory made boards.
Thank you Sir, I was eagerly waiting for this answer and now can make board for my other projects also...

Thanks again...
coullp1 year ago
What an excellent Instructable. I'm definitely going to make one!
Just one small thing, in the materials list, I believe it should be 100uF electrolytic capacitor (rated 16v or more) not 100nF.
Libahunt (author)  coullp1 year ago
Thank you very much.
Also thanks for reading with such attention. That clearly was a typo, fixed now.