6. Electronics design
week 6
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
GROUP ASSIGNMENT
| Instrument | Primary Use |
|---|---|
| Multimeter | Measures electrical properties (voltage, current, resistance) and tests components (diodes, continuity). |
| Oscilloscope | Visualizes and analyzes electrical waveforms (voltage vs. time) for signal integrity and timing. |
| Function Generator | Generates test signals (sine, square, triangle waves) to simulate inputs for circuit testing. |
| Bench Power Supply | Provides stable, adjustable DC power with voltage/current control for prototyping and testing. |
| Logic Analyzer | Captures and analyzes digital signals (timing, protocols) for debugging digital/embedded systems. |
Key Applications:
- Troubleshooting circuits (Multimeter, Oscilloscope)
- Signal simulation/analysis (Function Generator, Oscilloscope)
- Powering prototypes (Bench Power Supply)
- Digital system debugging (Logic Analyzer)
- Component validation (Multimeter, Oscilloscope)
Basic Electronic Components
Resistors
Resistors limit current flow in a circuit. I learned how to identify resistor values using the color code system, where each color represents a specific number or multiplier. For example, a resistor with brown-black-red bands has a value of 1-0-×100 = 1000 ohms or 1kΩ.
You could use the “ BB ROY of great britain has a very good wife “ phrase to remember the colour code .
Or you could use Online generators where you could input the colors listed and it will provide the resistance value .
Resistor Color Code Calculator - 4 band, 5 band, 6 band | DigiKey Electronics
Use the following link for online resistance value generation.
Capacitors
Capacitors store electrical charge and release it when needed. They consist of two conductive plates separated by an insulating material (dielectric). I discovered how capacitors are used for:
- Filtering noise in power supplies
- Timing circuits
- Energy storage
- Coupling/decoupling in signal processing
Insulators and Semiconductors
I studied how insulators prevent current flow while semiconductors can be manipulated to either conduct or block current under specific conditions. This property makes semiconductors the foundation of modern electronics.
Transistors and MOSFETs
Transistors function as electronic switches or amplifiers. For MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), I learned about the three terminals:
- Gate: Controls the flow of current
- Source: Where current enters
- Drain: Where current exits
MOSFETs are voltage-controlled devices that can amplify signals or function as switches in digital circuits.
Diodes and Special Components
Diodes
Diodes allow current to flow in one direction only. I studied their function in:
- Rectification (converting AC to DC)
- Signal demodulation
- Voltage regulation
Zener Diodes
Zener diodes maintain a constant voltage across their terminals when reverse-biased beyond their breakdown voltage, making them ideal for voltage regulation applications.
Connectors
I learned to distinguish between male connectors (with protruding pins) and female connectors (with receptacles), and how they're used to create reliable electrical connections between circuit components or boards.
Circuit Applications
Rectifiers
I studied rectifier circuits that convert AC to DC:
- Half-wave rectifiers: Use a single diode to pass only positive (or negative) portions of an AC signal
- Full-wave rectifiers: Use multiple diodes to convert both positive and negative portions of an AC signal to DC
Fan Speed Control
I examined how capacitors can be used in fan circuits to control motor speed by altering the phase relationship between voltage and current.
Digital Logic
Flip-Flops
Flip-flops are bistable multivibrators that can store one bit of data. I specifically studied the JK flip-flop, which has:
- J input (Set)
- K input (Reset)
- Clock input
- Q and Q̅ outputs
These components form the basis of sequential logic circuits used in memory and registers.
Logic Gates
I reviewed basic logic gates (AND, OR, NOT, NAND, NOR, XOR) and how they implement Boolean functions to create combinational logic circuits.
Electronic Design
We are using kicad software for the design process . i will share the processes involved for the designing and some basic functionalities .
Kicad software
I have downloaded the windows version for kicad . Download and install it . Using the above link .
This is how the home page looks like . Go to the file > click new project > choose file location . and you could get started .
Then click on the .sch file so you could edit the schematics .
Then i was in to the schematic tab which is shown below
Some functions are listed below
1 indicates : You could choose between components by selecting that button or press the letter A
2 indicates : Wire , or you could use W 3 indicates : you could cross the points where there is no connection. 4 indicates : You could assign a global annotation . so it can be used in different parts of the circuit . so there is no requirement of direct connection . you could assign the variable in place where the connection is required . 5 indicates : You could write some text using it .
Now the instructor told that we are doing our first sample project using ATTINY 412 . Then used the A button ( Place symbol) .
Then a tablet like this would open . You could search for the required component here . if not found you should download the schematic and footprint of the component and add it separately .
SnapMagic Search | Free PCB Footprints and Schematic Symbols
You could use the above site for getting components schematics .
Search for the component that you are looking for here . Here i am looking for ATTINY 412 . so i searched for it .
I got a bunch of options as listed below . select the one that you want .
I choose the one that i required , but in my case schematic was not there . so you need to build it your self . You could use the Build option as listed above .
Click on build and then You would get the datasheet . As in arrow marks 1 . i had gone to the pin out diagram of the component . then i have written the same on 2 . 3 : indicates a Plus button where you could add columns. 4 : After completion click generate part .(steps are shown in above diagram)
Then click on download and foot print tab and choose the version that you want . i have chosen v6.
Then go to home page of kicad again and choose Preferences > click on Manage Footprint libraries. (Nb : Repeat the same step for symbol libraries too )
choose the file location and it will be added . extract the downloaded file before .
Next step is to Add the fab library .
For that go to the drive where Kicad is stored . In my case it is c drive . then i have created a folder called kicad . inside that a folder called libraries and i have opened the git bash terminal there and cloned the fab library to it .
Steps Involved
pub / libraries / electronics / KiCad · GitLab
use the above link to go to the library then click on code and then copy the ssh link .
Use git clone command and paste the ssh and press enter on the library folder .
Then the fab library will be cloned to your system . change the name of the cloned fab library to fab . When downloaded it will be named kicad to avoid confusion in the future change to fab .
Then go to preferences and continues the step . add the library to kicad.
Choose the fabkicad.sym file
Then click ok to add the symbol library .
To add Foot print library . choose the file called fab_pretty .
Then press ok
Now fab library is added and we are ready to use .
Now go to schematic page and design the circuits by adding components .
Press A , search for the component and add it . use fab before the search so you could find the ones from fab library . Thats the reason why we changed the file name .
If you are in doubt of how much resistance you should add .
example : in the case of led check the data sheet .
The marked values are the ones that we require to find the resistance . then go to Digikey website and enter the values so you could find them as follows .
LED Series Resistor Calculator | DigiKey Electronics
Now check the available inventory . and choose the right one .
Fabstash is our local inventory database .
Draw the schematic accordingly . after the schematics are drawn . Based on the above image . Click 2 for checking any misconnection or anything wrong in the circuit . Click 3 for the Pcb design
BOM
| Reference | Quantity | Value/Part Number | Footprint | Datasheet |
|---|---|---|---|---|
| C1 | 1 | 10nF (NP0 1206) | fab:C_1206 | UPY-GP_NP0 |
| C2 | 1 | 10µF (Note: NP0 caps typically ≤100nF) | fab:C_1206 | [Same as C1] |
| D1,D2 | 2 | LED_1206 | fab:LED_1206 | |
| J1 | 1 | JST PH 2mm SMD | fab:Header_JST_PH_1x02_P2mm_Vertical_SMD | ePH.pdf |
| J2 | 1 | FTDI Pin Header | fab:PinHeader_01x06_P2.54mm_Horizontal_SMD | ~ |
| R1 | 1 | 1kΩ Resistor | fab:R_1206 | ~ |
| R2,R3 | 2 | Resistor (Value unspecified) | fab:R_1206 | ~ |
| R4 | 1 | 0Ω Jumper | fab:R_1206 | ~ |
| SW1 | 1 | Omron Tactile Switch | fab:Button_Omron_B3SN_6.0x6.0mm | B3SN |
| U1 | 1 | ATTINY412-SSF MCU | fab:SOIC-8_3.9x4.9mm_P1.27mm | ATTINY412 |
| U3 | 1 | LM3480 5V Regulator | fab:SOT-23-3 | LM3480 |
This is how the pcb designer tab looks like when empty . then click on the file button and setup the board . File > Board setup
After that write down the following constraints
Then arrange the components in a manner where the connections are less complex
On the Right side there is a panel where you should do the editing on Fcu . Make the F.fab hidden so that the letterings are hidden. Then draa the outer cut rectangle on the edge cut layer on the right side . click edgecut> choose rectangle tool and draw .
then click X and draw the track between (interconnection lines) . Make sure u are drawing on the FCU layer
First draw track between every connection except the ground and the power .
At Last draw the connection for the Ground and Power
After the drawing this is how it looks like . In my case one track was not able to be dawn . In that case you could use the help of zero ohm resistor to make the the track jump over a track .
For that you should go back to the schematic and add a zero ohm resistor like this where it is connected to the part where the track has to be jumped . in my case it was between grounds so i have it as ground
You could see the connection that i wanted to establish through the below diagram .
Here i have added R4 across so that i could jump the tracks and made them connect between .
You could use the below options to 1 : used to view the pcb layout in 3d 2 : check the things out . (Design Rules Checker) 3. Go back to schematic view
3D View
This is how the 3d view looks like . because there is some error in fetching the designs . To fix that .
In the pcb editor tab. Right click at the component then one tab would open click on properties
Then a tab like this would open > click 3D models > select the destination folder where the 3d models are there or download and add the 3d models.
In my case most of the models are available with Fab library .
This is how it looks like when you are adding components .
Next i have to design something my own . Now am aware about the basic tools used . So now i am using xiao rp 2040 for the development .
I took Xiao Rp 2040 From the symbol Tab (A) and i have placed as
I took Xiao Rp 2040 From the symbol Tab (A) and i have placed in the schematic tab , then i assigned global variables for each Pin .
This is the way how to assign Global Label .
Now i was in a need of a pin socket with 6 pins . Only 5 pin ones where available . so i decided to edit them and make to 6 pins .
Click Foot Print Editor on the Top Tab Foot print editor > Choose the Pin to Edit . Copy and paste the pins to below . In my case . i copied 2 and 4 then i brought it down and pasted 2 over 4 so that the new 4th pin is equal distant from the rest pins . (Or you have to take a length and do it )
Double click and change the Pin name from 4 to 6 . and you could edit the position so that it alligns correctly . Refer the previously pins that are in position to get the correct alignment.
This is how it looks like . save it . Now the footprint is added . Now you have to alter the symbol .
For that go to the symbol editor tool on the top .
Search for the item that you wanted to edit . copy and paste the pin and rename it to 6 . Press ok .
Next step is to assign the foottprint . There is a button called assign footprint at the top . click that
Then a tab like this would come up . Follow then 1,2,3 as listed above . Select the Library of the footprint that which you have changed . In my case the lib name is Fab .
Then the updated ones would be come up with a slight yellow color . Thats the thing that you want to be updated .
Then select that and choose the footprint . (Step 3)
So the footprint is updated .
My design was to make a simple development board using XIAO RP2040 . with a led and a switch
I have chosen the required components that i require from the symbol (A) Tab . and made my circuit .
Below i have attached the BOM used .
| Reference | Quantity | Value/Part Number | Footprint | Datasheet |
|---|---|---|---|---|
| D1 | 1 | LED_1206 | fab:LED_1206 | Error: Restricted Access |
| J1 | 1 | PinHeader_02x02_P2.54mm_Vertical_SMD | fab:PinHeader_02x02_P2.54mm_Vertical_SMD | 95278.pdf |
| J2 | 1 | PinSocket_01x03_P2.54mm_Vertical_SMD | fab:PinSocket_01x03_P2.54mm_Vertical_SMD | NPxCxx1KFXx-RC |
| J3 | 1 | PinSocket_01x04_Horizontal_SMD | fab:PinSocket_01x04_P2.54mm_Horizontal_SMD | 2.54mm-socket-spec |
| J5 | 1 | Conn_01x05_Socket | fab:PinSocket_01x05_P2.54mm_Vertical_SMD | ~ |
| M1 | 1 | Module_XIAO-RP2040 | fab:SeeedStudio_XIAO_RP2040 | XIAO-RP2040 |
| R1,R2 | 2 | 499Ω Resistor | fab:R_1206 | ~ |
| SW1 | 1 | Switch_Tactile_Omron | fab:Button_Omron_B3SN_6.0x6.0mm | B3SN |
Then i have switch to pcb editor and i have tracked the design . also i have fixed my pcb size to 70*50
And This is my final design .
Then i was Trying with some additional tools / Plugins that would help in my future process .
In reference to the steps mentioned above :
1 : Freerouting : It helps to automatically route the traces in the pcb .
2 :Gerber To Order : It helps in making printable files .
3: Round Tracks : Helps to make your tracks smooth (Round) .
4 Bulk hide designators : It hide all the writings in a single click .
5 Pin Out generator : It helps to see the pinout . Select the symbol whose pinout you wants to see and then click on PinOUt . so it generates .
6 : Transform it : You could rotate and do some transform functions using these Tools .
This Video helped me finding this .
https://youtu.be/2RKpluurhMA?si=o67BGbNJsgpEYWYQ
This is the 3D design that i have generated .
Next you have to Export them as Gerber file for that .
Go to the Pcb editor > Click Files > Fabrication Outputs > Gerber
Then a file like this would open , create a folder named gerber as instructed on the destination folder .
You could export the files by clicking Plot and then alos generate drill files if there is drill required .
Or use the extension that i have mentioned before .It will automatically generate all the files required in one click .
You could use the below website to view the Gerber View .
Conclusion
This week focused on gaining a foundational understanding of electronics design principles and their practical application using KiCad. Key concepts such as resistor color coding, capacitor functions, transistor operation, and digital logic were explored, alongside hands-on experience with schematic capture, PCB layout, and component selection.
The culmination of this week's learning was the design of a custom development board centered around the XIAO RP2040 microcontroller. This involved creating custom components (like modifying a pin header), incorporating external components like LEDs and switches, and routing traces on a PCB layout while adhering to design rules. Additional tools and plugins within KiCad were also investigated to streamline the design process.