Electronics Design

---

Hero shots

My design files:

• PCB
• Schematic

Goals for Week 06:

Do the group assignment,

Use an EDA tool to design a development board that uses parts from the inventory to interact and communicate with an embedded microcontroller

Group assignment page:

• Group assignment page

Takeaways from the group assignment:

The Astro AI digital multimeter was used to measure voltage, current, and resistance in electronic circuits and devices, helping diagnose faults, test batteries, and verify correct voltage levels. We connected the probes properly and used the multimeter to read voltage in ohms, observing measurements in a 5V circuit. The experiments included testing red and blue LEDs with a breadboard setup, where we analyzed forward voltage differences. The blue LED required a higher voltage than the red, demonstrating how resistance affects current flow and LED brightness. Using an oscilloscope, we visualized voltage fluctuations in an Arduino-controlled LED circuit, observing square waves due to rapid on-off switching. While we did not use transistors, we noted that MOSFETs are preferred over BJTs in many applications for their efficiency and ability to precisely control current. These experiments enhanced our understanding of circuit components and measurement tools.

Electronics Design

In-Class Electronics Design

First, we installed the fab library at this file location.

In order to have the symbols from the fab library actually show up, we clicked Preferences > Manage Symbol Libraries.

Click the plus button at the bottom, and put in the fab symbol library (fab.kicad_sym). MAKE SURE YOUR NICKNAME IS 'fab' WITH A !!!!LOWERCASE!!!! 'f'!!!!! Your symbol library won't actually import correctly if not.

Next, we'll move onto the footprint library. Click Preferences > Manage Footprint Libraries.

Follow the steps shown in red in the image. Use fab.pretty. Again, MAKE SURE YOUR NICKNAME IS 'fab' WITH A !!!!LOWERCASE!!!! 'f'!!!!! Your footprint library won't actually import correctly if not.

Finally, go to Preferences > Configure Paths

Press the '+' button, and add 'Name' FAB with the path including kicad-master. Click 'ok'. We should be fully set to start designing with the PCB and schematic editors.

The basic components for the circuit we made in class.

How to change the value of a component (Symbol Properties, left menu).

The finished circuit in schematic. We can switch to PCB by pressing the button circled in red.

ESP32 Circuit Board Design

To make a keypad and LCD screen design, I realized that I would need at least 12 pinheaders. 8 for the keypad, and 4 for the lcd display. Importantly, the lcd display needs a 5V and GND connection. The lcd screen also needs 2 I2C pins. The keypad just takes 8 digital pins. I made my traces to the ESP32 with this in mind for sure.

Use the document below to understand how to export the board from KiCad all the way to uploading the files to VPanel for cutting. Use this link to access mods.

A classmate taught me how to solder. I used soldering paste and the hot iron because that gave me a more precise application. Examples of my soldering are pictured below.

This was my first design. There are several flaws with this design that I fixed, which I discuss below.

While 10 mm/s speed is standard, the tip of the endmill kept snapping off halfway through the job. To fix this, we changed the speed from 10 mm/s down to 6 mm/s for the traces.

The first issue I encountered was one of the traces touching GND, resulting in a short circuit. I fixed this by carefully removing some of the copper trace with a x-acto knife.

Unfixed

Fixed

Next, I realized that 3 of the pins were having a short. This was because I made the traces much too close around the resistors for the bottom 4 pins. I fixed this by milling a new board (I probably could've used the technique above, but I thought milling a new board would be more time effective.) I made sure to make the traces around the resistors further apart.

When I fixed this problem, I encountered another: The traces near the resistors were also too close. As you can see, the solder paste from one trace to the next is touching. I fixed this with the new board design below. I made sure that the traces were very far apart, which gave the traces a square pattern.

New Board

The final issue I encountered was the fact that I had unnecessary 10 kOhm resistors that were messing up the inputs from my keypad. I was under the impression that all input devices needed 10 kOhm resistors for each pin. However, this is definitely not the case for keypads. I removed the unnecessary 10 kOhm resistors with a hot air soldering iron and tweezers, and my board was finally fully functional.

The final fully functional board in real life.

Conduct the Electrical and Design Rule check & show errors:

There are 5 errors. However, they actually do not need to be fixed, as these are just messages that the pinheaders are clearing the edge of the board. They do not need to be fixed as this was a stylistic choice on my part, as the pinheaders do not have to fully be on the board, and it's easier to connect wires if they're slightly off the board. The pinheaders are also just barely off the edge of the board, none are more than halfway off the board.