Anna Aflalo

Fab Academy 2015 | Wgtn

WEEK 6 | Electronic Design

Eagle design
First of all, thanks Anna for this amazing tutorial!
Download and install Eagle here
After downloading the fab library, I've completed my libraries with adafruit.lbr, SparkFun-Connectors.lbr and SparkFun-Resistors.lbr.

Other useful links:
Sparkfun Eagle tutorial - Schematic
Sparkfun Eagle tutorial - Board

List of components that I used:
- ATtiny 44: the microcontroller, the brain to send informations to the board,
- 5V Regulator: to maintain the voltage at 5V,
- 20 MHz Ceramic Resonator: to keep track of time,
- Screw Terminal: to provide power, (finally it's not a screw terminal because I selected the wrong component in my schematic but I still can manage to plug power),
- Header (2x3 pins),
- Header (1x6 pins),
- LED (Light Emitting Diode),
- Push button,
- 3 capacitors,
- 3 resistors: to limit the current and protect the components.

Ohm's law: V= I x R
Schematic process:
- Import your components,
- Label your pins,
- Write the value of your components if needed (ex: resistors),
- Connect your wires/net,
- Check your schematic with "ERC Errors" function: some warnings tell you when pins aren't connected to anything or when your components don't have value. CAREFUL: this information is useful but it doesn't mean that your schematic is wrong.
Then switch to board and design your circuit:
At the beginning I tried to design all the "routes" between the components manually. I had too many issues with my ratsnest. So I decided to use the autorouter (Effort: High, Bottom: N/A) but my board was such a mess that I couldn't fix it! I had to start my board from the beginning. Anna's tutorial helped me to place the ATtiny44, the headers and the resonator at right locations. Then I added the other components. I used the autorouter to draw my routes. Then I downloaded the fabmodule.dru file and used the DRC function. It informed me that some of my lines were too close. So I fixed it manually.
Tip: if you have a bench of resistors, use it to jump over the top lines.
If you want to make a circular board, add a circle on your "Dimension layer".

To export your images:
- Select only the layers "Top" and "Pads",
- Files -> export "image",
- Set parameters: monochrome, resolution: 2400dpi, area: full,

Do the same process with the "Dimension" and "Pads" layers.
Tip: check your images, they have to be the same size.
On photoshop:
- Add a logo,
- Fill your circle with the bucket function.
Milling
This week I had some issues milling my board. To start I broke the tip of the 1/64 endmill. I didn't tighten it enough with the allen key. So I had to get a new one.
As you can see on this picture, I also had so issues to mill my board. The bed of the machine wasn't even. With Jasmin we tried to fix it with a screw driver. And we checked the z-axis by moving the endmill's position at different locations of the bed.
Soldering
I FINALLY finished my board!

Click here to download the files: .png, .sch, .brd.