Week 6

Electronics Design

This week's assignment focuses on both group and individual tasks related to microcontroller circuits and development board design. For the group assignment, we will use the test equipment available in our lab to observe the operation of a microcontroller circuit board. Individually, we will use an EDA tool to design a development board that incorporates components from the inventory to interact and communicate with an embedded microcontroller. Additionally, for extra credit, we have the option to design a case around our development board.

Basic components

Component	Description
Ribbon Cable	A flat cable with multiple parallel wires, used to connect internal components in electronics. They can be used for data transfer or power distribution.
IDC Connector (Insulation Displacement Connector)	A type of connector that pierces the insulation of a ribbon cable to make electrical contact. These are commonly used in ribbon cables for quick and reliable connections.
Button	A simple switch that completes or breaks a circuit when pressed.
Switch	A device that opens or closes a circuit to control the flow of electricity. Can be manual (like a light switch) or automatic (like a relay).
Resistor	A component that limits or controls the flow of electric current. Measured in ohms (Ω).
Capacitor	Stores electrical energy in an electric field. Unpolarized: Can be connected in any direction (used in AC circuits). Polarized: Must be connected with the correct polarity (e.g., electrolytic capacitors).
Crystal	A piezoelectric component that generates a precise frequency when voltage is applied. Used in oscillators for timing in devices like microcontrollers.
Resonator	Similar to a crystal but less precise. Combines a capacitor and inductor to create a resonant frequency.
Inductor	Stores energy in a magnetic field when current flows through it. Resists changes in current, used in filters and power supplies.
Diode	Allows current to flow in one direction only. Zener Diode: Allows current to flow in reverse after a specific voltage (used for voltage regulation). LED (Light Emitting Diode): Emits light when current flows through it.
Transistor	A semiconductor device used to amplify or switch electronic signals. Bipolar Transistor: Has three terminals: collector, emitter, and base. Varies current flow between collector and emitter based on the base current. MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor): Has three terminals: source, drain, and gate. Varies resistance between source and drain based on the gate voltage.
Battery	Stores chemical energy and converts it to electrical energy. Provides DC (direct current) power.
Regulator	Maintains a constant voltage level in a circuit. Examples: Linear regulators, switching regulators.
DC-DC Converter	Converts one DC voltage level to another (e.g., stepping down 12V to 5V).
Op-Amp (Operational Amplifier)	A high-gain amplifier used for signal conditioning, filtering, and mathematical operations. Key concepts: Differential Amplifier: Amplifies the difference between two input voltages. Negative Feedback: Reduces gain but improves stability and bandwidth. Voltage Gain: Ratio of output voltage to input voltage. Filter: Removes unwanted frequencies from a signal. Follower: Output follows the input voltage (unity gain). Transimpedance: Converts current to voltage. Transconductance: Converts voltage to current.
Microcontroller	A small computer on a single integrated circuit. Includes: GPIO (General Purpose Input/Output): Pins for digital input/output. I2C, SPI: Communication protocols for connecting peripherals. ADC (Analog-to-Digital Converter): Converts analog signals to digital.
Sensors	Devices that detect changes in the environment (e.g., temperature, light, motion) and convert them into electrical signals.
Actuators	Devices that convert electrical signals into physical action (e.g., motors, solenoids, relays).

Key CAD

Ki Cad is a free software suite for electronic design automation (EDA). It facilitates the design and simulation of electronic hardware for PCB manufacturing. It features an integrated environment for schematic capture, PCB layout, manufacturing file viewing, ngspice-provided SPICE simulation, and engineering calculation. Tools exist within the package to create bill of materials, artwork, Gerber files, and 3D models of the PCB and its components.

Link : KiCad EDA - Schematic Capture & PCB Design Software

Installation of KiCad and set up

• Fist step is to download key cad from the official website from the provided link download the latest version . Download Link : https://www.kicad.org/download/
• Then next step is to install the software go to you downloads folder and open the downloaded exe file to initiate installation.
• Then open KiCad then from the top left corner go to files and new project then give a name and navigate to the location where you want to save the five a save it there

• Now open the file
• There will be two types of file on the right window Kicad_pcb and Kicad_sch
• Here the Kicad_pcb file have the design of the PCB and Kicad_sch contains the circuits for the design
• As the next step we have to import some libraries of components made for fab academy these contains most of the components in our inventory.
• For this clone the repo from the link provided in the link to your drive where you have installed KiCad and make a File KiCad >> Libraries and clone the repo inside this file. Link : pub / libraries / electronics / KiCad · GitLab
• Copy the SSH Key and clone the repository using git bash.

Sorry for the spelling mistake 😁

• Then from the top section in preferences in preferences

  

  • First to add symbol libraries click on the and click on the file button from the window that appears and go the file location where we cloned the repo and then select the kicad_sym file and press ok.

    

  • For the next step from preference select the footprint library follow the same step but in the last step select the file and and move on.

• Then the next step will be to select the micro controller and go through the data sheet for this trial project I am using an ATtiny412 Data sheet Link : ATtiny212 / ATtiny412 Complete
• And then in the schematic editing workspace import the components and make the basic circuit.

Schematic Editor shortcuts

• A → Add a component
• M → Move a component
• R → Rotate a component
• Y → Mirror a component
• E → Edit properties
• C → Copy a component
• Delete → Remove component
• W → Start a wire
• G → Drag a component while keeping wires connected

Schematic Interface

This is the basic interface of the schematic editor the tools in the right tool bar are used to make the circuit and the tools in the left tool bar are used to control the interface.the right tool bar contains tools to add new elements to the circuit, tool to draw track , tool to close of an unused pin etc, the image above can be used for getting a basic idea about the tools and the interface.

PCB Editor

• A → Add a component
• M → Move a component
• R → Rotate a component
• Y → Mirror a component
• E → Edit properties
• C → Copy a component
• Delete → Remove component
• W → Start a wire
• G → Drag a component while keeping wires connected
• D → Drag a track
• X → Route a new track
• B → Refill zones
• V → Change via size
• Ctrl + Shift + V → Paste special
• / (Forward Slash) → Switch between layers
• Shift + Space → Change track width
• Delete → Remove track or component

PCB Editor Interface

This is the basic interface of the PCB editor here on the right tool bar we have tools to add new elements to the circuit, tool to draw track , tool to add bunting box, tool to add text etc.From the top tool section we have tools to change the orientation of the components, tools to change the size of the grid, tools to edit the footprint of the components, tools to see the 3D view of the components,tools to import the schematic editor, ERC etc. In the 3D view port we can see the 3D model of the circuit.

Electrical Rules Check (ERC)

In KiCad, the Electrical Rules Check (ERC) is a tool used to verify the schematic for electrical design errors. It helps detect issues such as unconnected pins, short circuits, power conflicts, and input/output mismatches. It also identifies multiple power sources on the same net and checks that output pins are not directly connected to each other.Open the Electrical Rules Check dialog from the top tools menu.then run the ERC which will show the errors. Also make sure to add flags to ground and power or else this may cause an error.

• For learning about interface of Kicad and to learn watch the video tagged below. Link : https://www.bing.com/videos/riverview/relatedvideo?q=Kicad+using+documentation&mid=699C25CE8AA6202B7AF7699C25CE8AA6202B7AF7&FORM=VIRE
• After this make the circuit need in the schematic editor work space.

while designing makes sure that all the components that we are using for the design is available in the inventory. For this our amazing team of developers in super fab lab kochi have created a an amazing website for tracking the inventory of fab lab kochi.

Link : Fab Lab Kochi Inventory

• For finding the resistor needed for the LED I calculated the value of resistance using the ohms law.

• Ten from the top tool bar click on the Electrical rules checker to check if every connection hade been made if if shows any errors check through it make the necessary corrections.
• when there are no errors go into the PCB Editor workspace.
• In the PCB workspace first go the Bard setup from the top tool bar and add the parameters depending on the capability of the machine available.
• I changed the parameters so that it matches the capability of the machine available in our lab.

• Then arrange the components in a way that the number connection's overlap is less
• Then using the tools make the necessary connections then from the top tool bar use the design checker tool and make the corrections and confirm the design.

• Then finalized the design when there are no errors in the design.

• Then to add 3D design components select he component in the components in the PCB editing section then right click and in the 3D model section hover over the file path and select the location of the file ie, inside the library section go into the file which contain the step file and then select the component's step file.
• If the model is not properly arranged use the tools available on the side bar in this window to adjust the scale or Rotation or the Offset.

• Then import all the 3d files and assign it.
• This is the final out put. 3d design for some components were not available in the library if needed the file should be downloaded from other websites.

Exporting the PCB design

For exporting a pcb design From files go to fabrication Output and export as gerbers.

And from the window that appears click plot and all the files will be saved to the file if you give a output directory name the file wll be saved as a single folder with the name you entered, if you are making a multilayer pcb with holes press the generate drill files switch to generate the file for making the holes.These files that we received can be shared for PCB manufacturing.

Custom board With XAIO

Here my plan was to make a custom board with an XAIO ESP-32 C6 mounted on it with all the GPIO Pins, TX & RX Pins,I2C and Analog pins taken outside with pin slots . For this I started by referring the data sheet of the micro controller to learn about the micro controller and its outputs

Link : Getting Started with Seeed Studio XIAO ESP32C6 | Seeed Studio Wiki

Referring this image I made all the connection connections in the schematic editor and also separated each subsystem as separate boxes and used global label tool to make connections, I also added one power LED and also an LED to the GPIO pin 18 .And for testing and trouble shoot I added a separate button that can be connected to any GPIO pin using a cable. Then I added a header pin for connecting the I2C Connection.

Then in the PCB Editor section I made all the connection need for the PCB I also add all the missing 3D files for the electronic components. While making the tracks for the PCB I hade change some connects for making the path of tracks simpler Also I had to re-arrange comports in the PCB for a compact and aesthetic design for the PCB and i also made sure that the USB pin from the XAIO an be accessed.

Then I went into 3D View and rendered it to get the final result since the 3D file the micro controller was not with the file I downloaded from the Seed studio, I downloaded the file from and external website

Link : Seeed Studio XIAO ESP32C6 | 3D CAD Model Library | GrabCAD

And this is the final output

Then I exported the PCB design as STEP file and then imported it into fusion and designed Encloser for the PCB

Conclusion

This week's assignment focuses on both practical observation and design. As a group, we will use the test equipment in our lab to observe the operation of a micro controller circuit board, gaining hands-on experience with real-time analysis. Individually, we will utilize an EDA tool to design a development board that incorporates components from the inventory, enabling interaction and communication with an embedded micro controller. For those aiming for extra credit, an additional challenge is to design a protective case around the development board, integrating functionality with aesthetics.

Download Output Files