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6. Electronics design

This week I worked on preparing PCB starting from circuit design to soldering and then tested it.

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

Group Assignment

I worked on wiring hello.USB-serial.FT230x,RX(Receiver) and TX(Transmitter) for checking with oscilloscope. Also played as a camera woman for recording the group work.

Redraw an echo hello-world board - using EAGLE

  • Selected ATtiny412 for UPDI
  • EAGLE setup Import necessary libraries to EAGLE from Kannai instruction site and copy from managed libraries of EAGLE. Change “View” to de-select bottom four panels to have better workspace for Schematic and Board respectively.

  • Placed parts tentatively and assign values to capacitor 1uF, and resistor 1k.

place tentatively

  • Decided which pin of ATtiny412 to connect LED and button. Considered spaces, decided to assign Pin 7 to LED and Pin 6 to button. Chosen pin available for PWM to blink LED a bit slowly.

Pins for Pin and button

  • Schematic In order to avoid complication of presentation put GND at ends.


  • Design Rules : Set clearance as 16mil and size minimum width 16mil as well. Check errors by ERC.


  • Then switch to Board view and drawing connections. This process was solving a sort of PUZZLE! Although it was looking OK, I got warning / errors in DRC.


  • My drawing. There are some narrow paths. Let’s see if milling goes well or not…


Make it - using Fab module and MDX-15.

  • Narrow path successfully milled.

Milling Milled

Pick up parts per BOM

Two weeks ago, I lost a part. I learned better way of handling parts in the review and replicated. The parts were put on notebook with tape.

BOM parts

soldering , then testing PBC

Carefully soldering. I think I could do it much better than before.


Examination of connections. No errors found.

Test path Testing

Arduino IDE imported code and upload it thru Powershell to my PCB

Due to encountering errors, used Powershell for uploading codes.


Test 1 - Echo test.

Pins to cap. RX inflow - TX outflow

Capped to have echo.

Echo back

Test 2 - LED and button

Successfully flashed when pushed button


Eagle files


Arduino IDE files

Last update: July 2, 2021