MartinRisseeuw how to make almost anything

Electronics Design

Task:
redraw the echo hello-world board, add (at least) a button and LED (with current-limiting resistor) check the design rules, and make it. extra credit: simulate its operation

Description:
For this assignment I started with some tutorials on how to use the Eagle software. This tutorials can be found in the list at the bottom of the page. I used the help of our electronics guru Zaerc to explain me a few things. I created the helloBoard with an extra RGB led and TACT switch.

Scheme design:(image.1)
For my final project I have been working with some RGB LEDS, I want to be able to visualise different data with different colours. I decided to add an RGB led and switch to the helloBoard design. The extra parts needed for this are:

  • PLCC 4 RGB LED
  • 3x 499 Ω Resistors
  • 1x 0 Ω resistor
  • 1x 10K Ω resistor
  • 1x TACT Switch

I had exactly four pins left on the ATTINY44, so I was able to connect the RGB LED and the switch. I connected the switch to pin number 5 and added a 10K resistor and ground(image.1). The RGB led is connect to pin numbers 6, 10 and 11 (image.1) between every pin to the RGB led I put a 499 Ω Resistor(image.1).

Board design:(image.2)
The board design I found the most difficult part, I was too stubborn for not wanting any cable bridges and 0 Ω resistors. I tried to figure out how to place everything without adding a bridge or a 0 Ω resistor. This took me a whole day until Dave and Zaerc convinced me you can not always do without cable bridges and 0 Ω resistor jumps. I added one cable bridge and one 0 Ω resistor bridge.

Milling:(image.6,7&8)
With the milling I feel quite comfortable with setting up everything because I already did this a couple of times. The first try went wrong because the settings where changed and both the milling traces & cut out board didn't start on the same X and Y position.(image.7) The second try worked.

Tip: Always make a picture from your settings before milling so you know what went wrong.

Assignment images:

3D print settings
image.1 Scheme design in Eagle
3D print settings
image.2 Board layout
3D print settings
image.3 Design Rules check
3D print settings
image.4 Board milling traces eagle
3D print settings
image.5 Cut out board
3D print settings
image.6 left PNG milling traces & right Cut out board
3D print settings
image.7 Milling mistake
3D print settings
image.8 Milled out board
3D print settings
image.9 Board with components
3D print settings
image.10 Create present from the current view

Conclusion:
Forms follows function, because I was too busy thinking how my board would look like I took a lot of time in figuring out something that was impossible. I could not design the board without making a cable bridge. One thing I do want to learn is how to create a double sided circuit board so I can do this in a nicer way.

Eagle isn't the easiest program to learn but the tutorials from the bottom list helped a lot for the basics.