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 cam.py doesn’t accept Protel Gerber. I played around with editing the Gerber file and with editing cam.py, 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?
· 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 cam.py. (Why doesn’t python cam.py <filename> work?)
· Set the X and Y offsets in CAM to be the same as where I want the board to be made.
· From cam.py 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.)