Construction instructions, pictures and videos are available here. Hardware Rev F and previous designs are available for download from SourceForge . Support for SD an MMC cards in this version.

Some of this imformation may not relate to the latest release. I working to try and bring this up to date with the next release of hardware.

The latset revision board (Rev F) is available on the downloads page here. This is in Eagle format. You can download EAGLE CAD from


The schematics and related info for the AVR Butterfly can be found here. You can download schematics for the Rev F add on board containing the MP3 decoder chip here in PDF format. The grey box on the left of the diagram represents all the ports connections available to the PCB from the butterfly.

The current Rev F schematic.

PCB Layout

The PDF version of the PCB can be dowloaded here. The location of butterfly port connections shouldn't be moved as they are positioned to fit (almost) exactly onto the bottom of the butterfly. "Port D" was not really required for electrical reasons, but was included to add physical stregnth to the device as these connectors are the only support for the board (at least in the prototype).

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Top component layout.
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Top view of PCB copper and silkscreen.
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Bottom component layout.
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Bottom view of PCB copper and silkscreen.

Bill of Materials

The basic idea

So you want to help? You just want to build this damn thing? Here's roughly what you'll need.

  • Avr butterfly from Atmel
  • VS1001 MP3 Decoder chip from VLSI Solution Oy
  • Custom PCB or some method of connecting chip to buterfly to MMC.
  • MMC or SD card formated as FAT16 using the first partition
  • Various passive components -
    • 2 x 0.1uF decoupling capacitors
    • 2 x 33pF ceramic Capacitors
    • 2 x 100uF electrlytic capacitors
    • 2 x 1Meg Resistor
    • 2 x 100K Resitors
    • 2 x 10k Resistors
    • 3 x 1k Resistors
    • 1 x 12.288MHZ crystal for VS1001
  • Nokia 3310 LCD (optional the orginal LCD is also functional)
  • AVR JTAG interface (optional but can really help debugging. Butterfly comes loaded with a bootloader otherwise.)
  • AVR ISP interface (optional but handy if you don't like the boot loader, are too poor for a JTAG or AVR studio just crashed and disabled the on chip debugging ;) )
  • Powersource; something around 3V is good. Don't even think about 5V. 4.5V is max for Butterfly. 3.6V is max on MP3 chip and MMC

Current bill of materials

The following is the up to date bill of materials for the latest version of the PCB. The parts are available from Farnell and digikey with the exception of a few items. If you cannot see the list below then it is also available here.

And where can I get those parts?

And how can I build it?

There is some basic software in the CVS that can be used to check the operation of the Hardware and test individual aspects of the hardware. You can find the systems test module here. (NOTE: This has not been updated for some time)

There are construction videos, pictures and instructions available on theses pages

Change history

The Rev_B design now includes a low drop out 3V regulator so power source is not really an issue, but if using 3V (2 x AA cells) then you can just replace the regulator on the PCB with a jumper from vin to vout.

The Rev_C deisgn uses a MAX1811 to handle charging a LiION (4.2V) Battery from a USB port.The design should really regulate the battery to 3.3V, but doesn't yet.

The Rev_D board now includes a switched capacitor regulator (Texus Instruments REG710-3.3) to maintain Vcc at 3.3V. Using an unmodified Rev_C board will work but the life time of the MMC will be reduced.

The Rev_E board has replaced the REG710-3.3 with a National Semiconductor LP2891 ultra low dropout regulator. This component uses much less current than the former part, while allowing us to still extract power from the battery over its recomended operating voltage range

The Rev_F board uses a MMC/SD card from farnell. It has been tested with a 1Gb SD card with FAT 16 file system. Logo Support This Project