Group Assignment:

  • Use the test equipment in your lab to observe the operation of a microcontroller circuit board (as a minimum, you should demonstrate the use of a multimeter and oscilloscope)
  • Document your work on the group work page and reflect what you learned on your individual page

Individual Assignment:

  • Use an EDA tool to design a development board that uses parts from the inventory to interact and communicate with an embedded microcontroller.
  • extra credit: try another design workflow
  • extra credit: simulate your design
  • extra credit: design a case around your design

Have you answered these questions?

  • Linked to the group assignment page. ✅
  • Documented what you have learned in electronics design. ✅
  • Checked your board can be fabricated. ✅
  • Explained problems and how you fixed them. ✅
  • Included original design files (Eagle, KiCad, etc.) ✅
  • Included a ‘hero shot’ ✅
Group Assignment

  • Use the test equipment in your lab to observe the operation of a microcontroller circuit board (as a minimum, you should demonstrate the use of a multimeter and oscilloscope)
  • Document your work on the group work page and reflect what you learned on your individual page
Group assignment

Teamwork

For this task, I used my personal oscilloscope, since the UNCP Fab Lab where I work doesn't currently have this testing instrument. So, I made the most of this instrument, as it's a PC oscilloscope with a good bandwidth (20 MHz). The software is intuitive.

In addition, it allowed me to better understand the concepts of measuring different signals. This measuring instrument is very similar to a bench oscilloscope.

The oscilloscope I worked with is the Hantek 6022BE, a 2-channel digital oscilloscope that connects via USB to a PC or laptop. Below are its technical specifications.

On the other hand, for electrical measurements, use the Mestek DM90E multimeter, a compact and portable digital multimeter, a reliable and versatile tool for those who need to take accurate electrical measurements in a variety of environments. Its combination of advanced features and affordable price makes it an attractive option for professionals and amateurs alike; it is a versatile and accurate tool for electrical measurements. Its main features are detailed below:

Hantek 6022BE Digital Oscilloscope

📊 Technical Specifications

  • Channels: 2 analog
  • Bandwidth: 20 MHz
  • Sampling rate: Up to 48 MSa/s
  • Vertical resolution: 8 bits
  • Input impedance: 1 MΩ // 25 pF
  • Input sensitivity: 20 mV/div to 5 V/div
  • DC accuracy: ±3%
  • Time base range: 1 ns/div to 5 ks/div
  • Memory depth: Up to 1 Mpts
  • Input coupling: AC/DC/GND
  • Input protection: Diode clamping
  • Interface: USB 2.0

Mestek DM90E Digital Multimeter

📊 Technical Specifications

  • DC Voltage: 600 mV / 6 V / 60 V / 600 V
  • AC Voltage: 6 V / 60 V / 600 V
  • DC Current: 60 mA / 600 mA / 10 A
  • AC Current: 60 mA / 600 mA / 10 A
  • Resistance: 600 Ω / 6 kΩ / 60 kΩ / 600 kΩ / 6 MΩ / 60 MΩ
  • Capacitance: 60 nF / 600 nF / 6 µF / 60 µF / 600 µF / 6 mF / 100 mF
  • Frequency: 60 Hz / 600 Hz / 6 kHz / 60 kHz / 600 kHz / 10 MHz
  • Temperature Range: -20°C to 1000°C (with K-type thermocouple)
  • Non-contact Voltage Detection (NCV): 90 ~ 1000 V AC
  • Display: 1999-count LCD with backlight
  • Sampling Rate: 3 times per second
  • Power Supply: 3 x AAA 1.5 V batteries

Reflections

  • While performing the measurements, I understood several fundamental concepts, since measurements with an oscilloscope and multimeter are essential in electronics, electricity, and engineering because they allow us to verify, diagnose, and validate the behavior of circuits and components. With the multimeter, we can measure current, voltage, resistance, among others, and with the oscilloscope, we can visualize the signals, measure frequency, amplitude, and period. In addition, we can compare two signals. These tools are essential for both electronic diagnosis and repair.

Individual Assignment

  • Use an EDA tool to design a development board that uses parts from the inventory to interact and communicate with an embedded microcontroller.
  • extra credit: try another design workflow
  • extra credit: simulate your design
  • extra credit: design a case around your design

To carry out the individual assignment consisting of the electronic design using the Xiao ESP32 C3 microcontroller, in this case the KICad EDA software was used, for which it was downloaded by performing the following steps.

On the main page, we select our operating system, in our case “Windows” and download the installer (.exe). The version we will install on our machine will be 9.0.2, the latest version.

Once the download is complete, the next step is to double-click the downloaded executable file called KiCad 9.0.2 and then click 'Next' to begin the installation process.

The installation process consists of continuing to click “Next” at each step until the installation is complete.


Electronic Design

Now we can open the program and create a new project, in my case I named it ESP 32C3, two files are generated, one is the schematic editor and the other is the board editor.


In the schematic editor, we start working on our diagram.


Symbol Library

We added a symbol library.


Library of Symbols Downloaded

We added a library of symbols downloaded from Fab Xiao's repository


Xiao ESP32 C3 component

We locate the Xiao ESP32 C3 component in the symbol library


Schematic diagram of the Xiao ESP32 C3

Once the Xiao ESP32 C3 component is located, we transfer it to the schematic sheet.


Footprint Library

Next, the Fingerprint Library is added by going to the preferences window


Display of the symbol and footprint of the XIAO ESP32 C3 module

This window displays the symbol and fingerprint of the XIAO ESP32 C3 module.


Pins and labels of the XIAO ESP32 C3 module

The schematic diagram shows the pins and labels of the XIAO ESP32 C3 module.


Preview of the schematic diagram of the XIAO ESP32 C3 module

Following the steps shows the progress of the schematic diagram of the XIAO ESP32 C3 module

PCB Design

In KiCad, enter the PCB Editor

In KiCad, enter the PCB Editor displayed in the project window


PCB Editor

In the PCB Editor, you update the data by using the Tools button and selecting Update PCB from Schematic.


Design on the plate

PCB updated, you can see the layout on the board.


Circuit design on the board

Design on the plate

With the updated PCB, we have all the components in a way that allows us to make the track layouts.


Track Layout

We carry out the layout of tracks, establishing the respective width, giving it a width of 15 mils (0.381 mm) is a width commonly used in PCB for: Low consumption signals (digital, analog).

Did you have any problems

Yes, as we were initially working on the top layer, I didn't realize that the footprints and track lines should have been on the bottom layer since the components were through-pin, and everything was going to be soldered on the bottom layer, so we had to correct that.


Track Layout

In this case the tracks will be on the bottom layer and the components on the top layer, which is why we have to place the tracks according to the layout of the components.


Add filled zones

We select the layer where we want the infill; in this case, we chose the bottom layer for the ground infill. A non-netted copper zone was used to reduce the milling area and conserve copper on the board. This optimizes CNC machining time, extends the life of the cutter, and improves the PCB's thermal and mechanical strength.


Gerber manufacturing file generation

Before we can generate the manufacturing files, we have to review the design rules to avoid errors when manufacturing. In this case, it was verified, having two warnings as a notice, which were corrected. Then, in the file, we look for the manufacturing output to generate the Gerber file.


3D Visualization on The Top Layer

Once these steps are completed, we proceed to 3D visualization, to see how the PCB would look.


3D visualization on the Layer Below

The image is now displayed in the 3D viewer with all its components.


Is it possible to manufacture my PCB board?

Yes, my PCB manufacturing is possible because the design meets the technical and practical requirements for production using CNC machining. Here are some reasons why this is feasible:

  1. Design compatible with CNC milling

    • In the software (KiCad), the tracks were drawn on the B.Cu layer (Bottom Copper), and the components were placed on the top face (F.SilkS for silkscreen and F.Fab for the physical outline).
    • CNC machining only removes copper from one side of the blank plate, making it easier and more efficient to work with a single layer of copper.
    • Adequate minimum track widths (≥ 0.3 mm) were used to avoid breakages.

  2. Correct generation of fabrication files

    The required Gerber and Excellon Drill files were generated to represent the copper layers, board outline, and drill holes. These files were processed in FlatCAM to create the G-code required by the CNC machine.

  3. Availability of tools and materials

    A desktop CNC milling machine with enough precision was available to carry out the process. FR1 copper-clad boards and appropriate milling bits were used for isolation routing and drilling.

  4. Controlled and repeatable process

    Copper isolation, drilling, and board outline cutting were performed in controlled steps. The cutting depth and speed were properly calibrated to ensure the integrity of traces and pads.

  5. Prior validation through simulation and visualization

    The design was verified using a Gerber viewer and CAM software before milling. Electrical connections, pads, vias, and board edges were correctly identified and validated.

Problems I had and how I solved them (design related)

One of the problems I had was regarding the design rules, I have worked with other design programs, quite similar, as it is a matter of more practice, it took me a little time to look for the appropriate tools and similar to those of other design programs, it is a matter of more practice, the design rules are very important, that is why I was investigating and researching to correct the errors that I had at the beginning, which I later corrected successfully, but I definitely like the design part and I am going to reinforce better to create more complete designs.

Conclusions

  • This week has been quite successful, as I had previously worked with PCB design software many years ago, such as Orcad, but due to time constraints, I stopped practicing it. The basic knowledge I acquired has allowed me to continue exploring. Above all, I want to delve deeper into the rules of printed circuit board design. Kicad is an open-source tool with many libraries that can also be downloaded and imported. It's quite interactive and very good for getting started in electronic design. It also allows you to view the board and its components in 3D. It's undoubtedly a very useful tool for electronic design.

Link to files used this week

1. kicad design.zip
1. file Gerber.zip