A set of stackable PCBs around the AVR atmega644p microcontroller
Added LICENSE file
Translated README to English
fixed missing connection on ISP header


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A set of stackable printed circuit boards around the AVR atmega644p microcontroller by DL7TUX, A55

There is obviously no shortage on AVR based controller boards. Does anyone need another? Nope. So this project is member of the category "Because we can!"

Tags: hardware, controller, SMD, KiCAD


  • These PCBs are designed with surface mounted devices (SMD). They can serve as learning to solder projects. Parts are of size 0805 or larger, footprints are large enough to allow manual soldering.

  • These PCBs are designed stackable using PC104 press-fit contacts, so they can be used together without the need for a back plane or special cables or similar.

  • The PCB featuring the controller is usable standalone. An ISP connector for programming and access to the serial port (ttl levels) via 4 pin headers should suffice to start.

#Design decisions

  • The form factor is clearly copied from the "Propeller Quickstart Board" by Parallax (see https://www.parallax.com/product/40000). Size is 3000 mil x 2000 mil, approximately 76 mm x 51 mm
  • The connectors are 2 x 20 pins of 100 mil (2.45 mm) distance.
  • There is a second connector. Its sole purpose is to expose all 32 signals of the controller. Consider these to be solder points.
  • Peripheral components, like status LEDs are not connected via traces at all. Any peripheral needs to be connected explicitly using wire. In other words: the layout does not decide on the use of the controller pins.

#Board 1 v1, v2

controller board

#Board 2 (display)

This PCB features a footprint to mount a LCDisplay featuring 4 rows of 20 characters each (EA DOGM-204). This display can be connected via 8 bit or 4 bit parallel bus, i2c or spi. The display is mounted on the back side of the PCB. Since it should probably be the topmost board in TheStack, it is recommended to use a normal connector with short pins. Switches or rotary encoders are thought to be mounted on a separate board or on any enclosure.

#Board 5 v2 (prototyping area)

This one took a few iterations. It is hopefully useful featuring pads, some through holes and a solderable area of ground plane (drill holes as you see fit). For convenience I added two SOIC footprints. Moreover there is one connected row of pads connected to Vcc and another to GND, respectively.


  • 2020-11-29 -- moved repository from gitlab.com, translated Readme to English. Readded missing Vcc from ISP connector!
  • 2019-04-03 -- board 2v2 (display): fliped top and bottom layer, because silk screen print is offered only on the top layer for the selected manufacturer (prototype boards). Increased drill from 1.15 to 1.7mm for press fit connector. Better mounting holes. Placed reset of display on connector J2, because it needs to be asserted once more after powerup of the display. Changed foot print on pullups/-downs on IM1, IM2, and RS such that only one selection can be made. Added footprints for resistors in i2c lines. Placed resistor foot prints to bridge i2c_sda. Removed Vcc fill from bottom layer.
  • 2019-04-03 -- Board 1v2 (controller): Increased drill from 1.15 to 1.7mm for press fit connector. Better mounting holes. Corrected foot print of main crystal. Cut loop in layout of Vcc. Removed Vcc from ISP connector (This turned out to be an error later! And yes it cost me considerable sweat. Don't do this). Changed orientation of C10. Added additional 4 pin header for ttl-serial and power.
  • 2019-03-31 -- board_template: Increased drill from 1.15 to 1.7mm for press fit connector. Better mounting holes. Moved label from FCu to FSilk layer and different place.
  • 2019-02-12 -- Added Files of CERN Open Hardware License. Added previews of board as png files.
  • 2019-02-11 -- Added Boards 1, 2, 4, 5v1, 5v2
  • 2018-12-20 -- Initial commit (https://gitlab.com/erwaelde/de_avr_boards)