Friday 11 November 2011

Calunium: PCB version

Calunium. Click on the image for an annotated version.

Calunium is an Arduino clone based on the ATmega1284 microcontroller. Initially a strip board design was created to test the concept. Following the success of the strip board version I decided to create a PCB version. Initially I hoped to include Wifi networking, an SD card and a real-time clock. It soon became apparent that including this many peripherals was not possible with the desired footprint using the free version of Cadsoft Eagle. The final version includes a real-time clock. Wifi networking (using the Roving Networks XV Wifi module) and storage using an SD card is provided by a shield designed specifically for Calunium. The RN-XV/SD shield will be described in a future blog post. The pin mapping of the PCB differs slightly from the strip board version; the Arduino software takes care of the differences provided the correct board type is selected.

  • Shield-compatible with Arduino Uno, with extra I/O laid out to be compatible with Arduino Mega pins. Pin mapping is chosen for maximum compatibility with Uno.
  • I2C (SDA/SCL) mapped to standard location as used by Arduino Mega but jumpers can be used to replace A4/A5 with SDA/SCL signals for compatibility with Arduino Uno.
  • Second UART (D1,D2) signals also mapped to corresponding location on Arduino Mega (TX1,RX1).
  • ISP header in standard location, allowing the Arduino ethernet/SD shield to be used.
  • D13 LED connected via FET to avoid loading D13.
  • Direct USB interface using V-USB, for firmware updates without requiring FTDI cable. Can be disabled by removing jumpers. Not yet tested.
  • Real-time clock (DS1307). Output square wave can be routed to D6 (INT2) or D15 (TOSC1, for input to timer/counter 2). Use either CR2032 or CR1220 battery depending upon battery holder fitted.
  • Power from USB or FTDI connector.
  • Switches, jumpers, connectors and USB socket outside of the standard Arduino shield footprint so they do not interfere with shields and are accessible when shields are fitted.
  • Auxiliary power connector; connect your own voltage regulator or boost converter. 5V from USB (FTDI and/or USB connector) and 3V from RTC battery also available on the connector. 3.3V operation is also possible.
  • Auto-reset can be disabled by removing jumper.
  • Pads to fit LM61 temperature sensor.
  • Usable PCB-mounting holes.
  • JTAG header for debugging/programming.
  • Eagle PCB design files available under Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0 licence.
  • Arduino files for Calunium are available on Github.


  1. Hi Steve,

    Really like your "Calunium" board which very usefully, in my view, fills a strange gap in the Arduino range. I can't understand why more interest hasn't been shown in th 644/1284 based stuff for the Arduino platform

    I've played around quite a lot with the Sanguino and like it quite a lot, but your effort to make a board with shield compatibity is great.

    Do you plan to make these boards available, on ebay, for example? I for one, would have a couple from you straight away!

    If not, could you please say where you got your boards produced.

    Many thanks for this really useful project.


    1. I have no immediate plans to sell any. I had my boards made by Iteadstudio.
      They are just under the 8x10cm limit set by the free version of Eagle so you can use the 10x10cm PCB option from Iteadstudio and have 10 boards made for $25. You need the Gerber files; they are in the Calunium Github repository. If you do get some boards made please let me know how you get on.

    2. Thanks for the info - looks like very good value for money.

      I will probably proceed with this soon, and I will certainly let you know how it goes.

  2. I was only looking for Arduino libs for the 1284 but this is really cool. Can't wait to get my PCBs :) Thanks a lot for sharing!

  3. Steve, You mentioned some where that you use iteadstudio for your PCB's. How do you have them shipped. DHL and UPS cost more than the pcb's. If you use airmail have you had any problems.

    1. I've ordered PCBs from Iteadstudio twice now and on both occasions I used standard air mail without any problems. My free gift from Iteadstudio didn't arrive but I think that was sent differently; I never contacted them about it. They state on their web page If your order by air mail is notified as “shipped” for 30 days without reception, please contact your post office and notify us. We will follow up closely to track the parcel, and refund/ reship in the worst case.

  4. Thanks for that info.
    I saw your comment at my blog about onboard regulators. I am using a conventional approach with the Daiduino keeping as close to the original Arduino form as possible, but it is obvious that you have put much thought into your design. I especially like the addition of the RTC. I have an Arduino clone which I have not yet posted, much like my Picduino, on which I squeezed an RTC, EEPROM and battery.

    Great work. Keep truckin'.

  5. Dear Steve,

    I just finished my own 1284p arduino. Your project guided me through a lot of the desicions! Thank you so much!


    1. Glad to hear it helped. Would love to see some photos.


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