Week 5: Electronics Design

Introduction

This week, I redrew the echo hello-world board (below) and added a button and LED (with current-limiting resistor). Then, I made the board using a similar process to the Electronics Production week. To design the board, I used the software EAGLE. (pic).

Phase 1: Design of the board

1. Install EAGLE
2. Import the Fab library in order to use the custom-made fab componenets. To do this, in EAGLE, go to File → Open → library and open up the Fab library



Create the schematic



3. Then create a new schematic (by going to File → New → Schematic)
4. Now in the schematic, I imported all the different components. In EAGLE, there are two ways to do things: (1) use the icons on the sidebar (2) type in the command. Here, I will show you how to do both. To add a component you can type ‘add’ in the command line
5. A new window will be opened – go to the ‘fab’ library. Tip: Use the wildcard * when searching for the components, because the search feature is not so good. For example: *resistor*
   
   Components I imported:
   • Resistor (RES-US1206FAB)
   • Resonator
   • LED (LEDFAB1206)
   • FTDI-SMD-HEADER
   • ATTINY 44 (ATTINY44-SSU)
   • Cap (CAP-Unpolarized C1206FAB)
   • Switch (6mm_switch6mm_switch)
6. Connect components – Use the ‘net’ feature to connect components together (pic). Tip: to move a component, you have to click on the ‘cross’ on the component
7. Click on the ‘net’ icon and create a line with the green net from the ‘dot’ of the component to some arbitrary point
8. Name the net by typing ‘name’ in the command line and clicking on the net you just created – enter a name relevant to that connection
9. Then label the net by typing ‘label’ in the command line and clicking on the net – you should see a label appear
10. Repeat steps 7 – 9 with all connections. Tip: To know if a net connected to a component, move the component around. If the net moves with the piece, then it is connected. If the net does not move with the piece then they are not connected






Create a board



11. To create a board, you can either type in ‘board’ in the command line or click on this icon (pic)
12. When you generate a board, you should see all the components with the connections (if all the connections were done properly)
13. To route the connections you can click on this icon (pic) or type ‘route’ in the command line
14. To export just the top of the board type ‘display none top’ and you will get the following image. (type ‘display all’ to go back)
15. Export the image – type ‘export image’

Phase 2: Making the board

I used similar instructions to the Electronics Production Week" to make the board.

Challenges

• I had a challenge with making the nets in the schematic. Initially, I made the net connections by using the green lines to connect from one piece to another. It was a mess. Because many of the parts I thought were connected weren’t actually connected. All the green lines were intersecting and all over the place. It was hard to debug. Frustrated, I tried another approach.

  

  

• Another problem I ran into was that the software did not calculate a path for the board circuit outline. This was because the border outline created in Eagle was too far to the edge so the software wasn't even recognizing it. Instead, I created a border in Preview.
• After the board was made, I noticed that the cutting didn't fully separate two parts as you can see in the picture. In order to separate them, I used a knife to cut away.