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Efe: Capacitive Sensing


We take the efe board and change the board and code to get a better idea of capacitive sensing, circuit design, and the ATTINY15.


·        There’s a general move to using the vinyl cutter to make circuit boards. I watched people try to make it work for a few hours today. Not encouraging.


·        Changing the circuit board:

o       I decided to add a USB connector to the board in place of the mini-molex because:

·        My final project will involve many efe/type simple microcontroller circuits networked together.

·        I am imagining users continually plugging and unplugging these circuits from each other.

·        The connectors to be easy for the user to use  i.e. big and tough.

·        Off-the-shelf cables with connectors would be a big time saver for me.

·        Note: I am not using the USB protocol. Just the connector.

o       I chose to remake the circuit in Protel and alter it in that environment:

·        Make the components

1.      is there a way to rotate components?

2.      make the “bulb” of the pin stick away from the chip

3.      rotate with the <space> bar

4.      Why am I getting “node not found” errors using the LED part?

5.      question on capacitor orientation

6.      what a mess of names everywhere on the PCB


after re-laying out the board in Protel I found that doesn’t accept Protel Gerber. I played around with editing the Gerber file and with editing, then switched to Eagle.


o       Using eagle

·        When I make changes to the Schematic, how do I update the board?

·        How do you connect components?

o       Soldering:

·        A great trick for soldering surface mount resisters etc.:

1.      Put a dab of solder on one of the pads

2.      put the resister on top of the pads. Press down on the resister and heat the pad w/ the solder

·        Don’t touch the solder w/ the soldering iron…the solder just evaporates.

o       Using the Modella --- a review:

·        To cancel, go into view mode and hit the up and down buttons at the same time. When the job is cancelled, the light will flash quickly.

·        Use move <x> <y> to move the modella to coordinates. 1 1 is 2 squares in and 2 squares back.

·        With the bit loose, move the modella to its furthest position down. Then move it up slightly, then tighten the bit. So the bit is resting on the board w/ the modella slightly higher than it’s lowest position.

·        Type cam <filename> to run (Why doesn’t python <filename> work?)

·        Set the X and Y offsets in CAM to be the same as where I want the board to be made.

·        From choose <contour boundary>, <raster interior>, <write toolpath>

·        Good values:

1.      Z up = .05

2.      Z down = -0.015

3.      XY speed 2

4.      Z speed 2

5.      tool diameter .-156

6.      contour undercut 0

7.      raster overlap .8 (or try a tighter overlap next time.)