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Spending some time optimizing my prototyping-tools, i finally got the atmega8-basic-circuit i searched for. i don’t need things like onboard MAX232 or FTDI, because i have modules for that. what i wanted was some AVR-module that is robust, compact and features a crystal, a pullup and ISP. here it is:

brickAVR lit

i soldered a row of female pin headers directly to the AVR-pins. they have a distance of 0.4″, so you could fit a custom protoboard-shield on top of the module. a 16 MHz-SMD-crystal was glued under the chip and connected to the pins, and so was the pullup. i glued an 6-pin ISP-header to the front of the chip and connected it to the appropriate pins. last but not least  i added an SMD-LED to indicate power-on.  that was it for the electronics. next i filled the space between the female pin headers and above the atmega with hotglue (sticking the led into it). finally i needed a case. i had some lego bricks lying around on the desk and more randomly picked one that seemed to match. amazingly it fit perfect after i clipped the sides of the ISP-header. so i glued the circuit into the hollowed brick and added a label i made in corel draw. that’s about it.

the module is powered by the programmer (USB) and i can access every single pin. i like to use it in prototyping applications where a whole breadboad would be overkill, fragile or simply too large. like when you  just want to create a specific output signal. the module also easily hooks up to a breadboard. here’s another two pics of the lower side and the raw circuit:


So i had these three servos and thought about how to use them in a project.  i saw flexpicker robots on the internets which were really impressive. had to have one. found six ball joints in my drawer and started to do some cad. i needed twelve ball joints or at least something comparable, so i had to make six from scratch. a few days of cnc-milling and drilling later i had my delta-robot. now it’s time to find a purpose for this thing. i thought about attaching some kind of head to it with an integrated display. i plan to control robot and display via rs232 and a microcontroller. so there’s more to come.


delta robot in uncentered position


delta robot closeup

While messing around with twi (that’s what atmel calls i2c) some time ago, i built this little device that does nothing more than listening to the bus and display all the bytes it receives on a two-digit 7-segment-display in hex-format. the motivation for this project was not only “i need this thing” but also “i’m tired of coding and want to solder something. and i have to get rid of these displays anyway”. the schematic and layout was done in eagle. an atmega8-controller (overkill) handles bus and display. the whole device is powered by the bus.

here’s two pics:

top side of i2c-slave

bottom side of i2c-slave

yes, i forgot one line 😦

Some time ago i got into rubik’s cubes by accident. after a while i thought it would be nice to solve the cube using a different perception than the visual. i decided that i wanted something haptic.  so i went and designed some patterns that were

  • easily distinguishable
  • systematic
  • plain
  • easy to make
  • rotation invariant


    the result were three different basic shapes: cross, box, hollow box

    Cube Patterns

    “why no circle?”. well i decided to stick to the concept of straight lines. but i added some roundings just for a more comfortable feeling. anyway, it’s three basic patterns in a normal and diagonal version each since the colors on a rubik’s cube are also paired. we have [red/orange], warm colors on opposite sides of the cube, [white/yellow], bright colors and [blue/green], cold colors.  i wanted to keep that concept in order to have a better orientation when solving the cube. so each [normal/diagonal]-pair is located on opposite sides of the cube.

    finally the plates were cnc-milled out of  pcv and it was a really painful amount of work to clean them with steel wool.  it took a while till i got my fingerprints back. i peeled off the original labels of the rubik’s cube and mounted the plates using double-sided tape.

    54 plates later the cube was finished. the first days the cube felt a little uncomfortable, but it became better because the edges wore off. solving the cube takes me about five times longer than solving a normal cube, but it’s an interesting challenge every time.

    here’s a picture of the finished cube:

    finished cube

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