Welcome to My Notebook on Son's Notebook

Tutorial on Kicad, Solidworks for Quick Prototyping

Wed, 24 Dec 2025 00:00:00 +0000

Hello, fellow students! I’m Son, a beginner in KiCad and SolidWorks. The steps below will help you get familiar with KiCad or SolidWorks quickly. I hope that after following these basic steps, you’ll be able to start building simple prototypes.

Final Product#

Kicad#

Requirement#

First, we need to define what we’re designing. Our goal is to create a fuse box for voltage sense lines.

We have a total of 11 sense lines, and each one must have a fuse to protect the end device or downstream device. Our device can handle up to 300mA at peak, so choosing a 500mA fuse seems like a good option.

Things I wish I knew working on a research paper

Thu, 02 Apr 2026 00:00:00 +0000

Hi community fellows. This note is based on my experience. And I hope it will save you time working on a research paper for the first time. In this note, I will show how I organize files and folders to make a research more systematic.

Date: 4/2/2026
Revision: 4/2/2026

Survey ( or review)#

The purpose of a research is to find something new or make an improvement on existing thing. To do so we need to review existing works.

On Learning

Sat, 04 Jul 2026 13:32:00 -0400

The knowledge that each person has always stunned me. I have two ways of learning: from books and from other people. However, we should note that books are products of people. Essentially, we just learn from experience, observation, and thoughts of other human being. What we learn here are vast. Why I keep on learning? I guess it’s a low risk, high return activity to enjoy life.

Learning from Reading Materials#

Books#

Self-Help#

I don’t know if self-help belongs to non-fiction or fiction. I read a few books and see a common pattern. They can be into two categories: motivational, and life improvement.

Keep on writing

Sat, 04 Jul 2026 13:26:00 -0400

I like the ideas and the blog of Mark Zimmerman. This is a type of blog I can spend hours on reading. It is similar to Paul Graham’s essays

Mr. Zimmerman writes small note to share his thinking. Every note has a concise topic.

– Relate Notes: On Learning

Build hugo site with github page

Sat, 04 Jul 2026 00:00:00 +0000

The reason I want to move to Hugo is because it is more modern and flexible compared to my Jekyll site.

The instruction is quite clear on their site https://gohugo.io/host-and-deploy/host-on-github-pages/

First, as always we need to create a github repo, and clone it in our local machine.

Next, we will need to create a Hugo project. I’m using Windows so I will select Extended-edition here. To access PowerShell, from command prompt we can type pwsh

On Things Around Us

Tue, 29 Jul 2025 00:00:00 +0000

On a late night walk, what I have read came back to me. I like the idea from the book The Little Book of Being. It is introduced in Mark’s blog.

I read about a mindfulness practice that fully scan over our body to see all things that construct us. I have not read or might have missed the concept of scanning the surrounding space. In Chapter 32, Diana Winston’s suggest one to explore all directions.

On Solitude

Mon, 09 Jun 2025 00:00:00 +0000

This writing is inspired by a book from an American Psychologist, Clark E. Moustakas.

Loneliness is not alone. Many may say alone is by choice. In contrast, loneliness is due to our inaction or inability to connect with other people; however, in my perspective, they are all the same.

The journey starts on the day we were born and ends someday that we don’t know yet.

Road Trip to Quebec with Random Questions

Sun, 05 Jan 2025 00:00:00 +0000

“I write to remember, to challenge my initial thought and intuition”

I’m gratefult to have friends around and invite me to discover the world with them. We are born as travellers at least in my family. Sometimes, we stuck in work and did not realize that we have a choice to just stop for a moment and continue explore the world that we thought we all knew about.

50 Places to Visit in Canada

Mon, 22 Apr 2024 00:00:00 +0000

I continued to work with the code from the previous post. I made a list of beautiful places in Canada and learned many new things from it, especially about the Kermode bear.

Algonquin Provincial Park, Ontario ✅#

Map	Img

Geographical Location: Ontario, Canada; between Georgian Bay and the Ottawa River.
Establishment Date: Established in 1893.
Purpose: Algonquin Provincial Park serves as a provincial park to protect the environment and provide recreational activities.
Special Features:
- Contains over 2,400 lakes and 1,200 kilometers of streams and rivers.
- Named a National Historic Site in 1992 for its influence in park management and visitor interpretation programs.
- Home to diverse plant and animal species due to its unique location at the transition between northern coniferous forest and southern deciduous forest.
Summary: Algonquin Provincial Park is not only the oldest provincial park in Canada but also one of the most popular, due to its extensive size, variety of lakes and rivers, and its location near major urban centers like Toronto and Ottawa.

Note from son: Algonquian peoples are group of North American Native.

50 Famous Places in the World

Sun, 14 Apr 2024 00:00:00 +0000

After final exam, I decide to do something fun. I know a friend who can remember most of the capitals of countries in the world. So I decided to learn geography. And made a list of places that I wanted to go. With AI, this task took me about 5 hours; however, with the code structure available, we can expand to many other topics such as anatomy, psychology, and many more.

Example of axis in numpy

Tue, 27 Jun 2023 00:00:00 +0000

While working on the Kohonen Self Organizing Map, I encountered difficulties in understanding how the axis parameter in NumPy works. Initially, in a 2-dimensional scenario, we have coordinates (x, y), where x represents the width or number of rows, and y represents the height or number of columns in the matrix. However, things become more complex when we introduce another dimension.

For instance, let’s consider an array of pixels with a size of 10x10 and three color channels: Red, Green, and Blue. This array would be represented as (10, 10, 3), indicating the dimensions of width, height, and depth respectively. Here’s my understanding of it:

Racket for Beginners

Tue, 09 May 2023 00:00:00 +0000

Racket, why racket? I don’t know the main reason, but it is interesting and importantly my professor requires it for our Psychology course. I have never learned Racket before but I have a bit of experience in Erlang. In Erlang we cannot assign a value to a variable like Racket because = operator is a pattern matching that is similar to car and cdr. The game is totally changed in Racket. Now we can just define whatever value we want.

English Connectives

Thu, 04 May 2023 00:00:00 +0000

After many hours of googling, mermaid is finally run on Github Page, thanks to Jojozhuang. I may not write another note for mermaid so I put the info here.

First, we need to add mermaid: true into our post layout. Second, we need to use div tag as below.

<!--
 to use mermaid in Jekyll we need to wrap it with <div>
-->
<div class="mermaid">
 your_mermaid_chart
</div>

Note: this tutorial is for Jekyll. Currently, this site is ran on Hugo with Book theme. For this theme, we only need to add fenced code blocks:

Note for International Students in Waterloo Region

Wed, 03 May 2023 13:29:00 -0400

Congrats to all of you that already here in Waterloo Region. Today I will summarize the process of becoming an international student in Canada. And I hope you will have a great experience here!

Prep before the trip#

Firstly, I obtained a bachelor’s degree from a university in the US. While working, I prepared my application for a study permit and applied for graduate school in Canada. After submitting my biometric information, paying the required fee, and providing supporting documents, the embassy sent me a letter of introduction. This allowed me to obtain my study permit and begin my studies in Canada. Now you are relieved with paperwork. Let’s pack up and go. Before you book an airplane ticket please note that if you transit in the US, you must have a transit visa or travel visa. And don’t forget to bring some cash before your flight. Next, I will talk about the process at the airport.

R Notebook - dplyr

Mon, 25 Oct 2021 00:00:00 +0000

We are gonna go through filter(), arrange(), select(), mutate(), summarise(), group_by(), slice(), rename(), transmute(), sample_n(), sample_frac()

Pipe#

%>% is pronounced THEN

All-in-one Example#

manager <- c(1, 2, 3, 4, 5) 
date <- c("10/24/08", "10/28/08", "10/1/08", "10/12/08", "5/1/09") 
country <- c("US", "US", "UK", "UK", "UK") 
gender <- c("M", "F", "F", "M", "F") 
age <- c(32, 45, 25, 39, 99) 
q1 <- c(5, 3, 3, 0, 2) 
q2 <- c(4, 5, 0, 3, 2) 
q3 <- c(5, 2, 5, 4, 1) 
q4 <- c(5, 0, 5, NA, 2) 
q5 <- c(5, 5, 2, NA, 1) 
leadership <- data.frame(manager, date, country, gender, age, 
 q1, q2, q3, q4, q5, stringsAsFactors=FALSE)
> leadership
leadership <- leadership %>%
 mutate()

 manager date country gender age q1 q2 q3 q4 q5
1 1 10/24/08 US M 32 5 4 5 5 5
2 2 10/28/08 US F 45 3 5 2 5 5
3 3 10/1/08 UK F 25 3 5 5 5 2
4 4 10/12/08 UK M 39 3 3 4 NA NA
5 5 5/1/09 UK F 99 2 2 1 2 1
library(dplyr) #A 
# add total_score and mean_score columns
leadership <- mutate(leadership, #B 
 total_score = q1 + q2 + q3 + q4 + q5, #B 
 mean_score = total_score / 5) #B 
> leadership
 manager date country gender age q1 q2 q3 q4 q5 total_score mean_score
1 1 10/24/08 US M 32 5 4 5 5 5 24 4.8
2 2 10/28/08 US F 45 3 5 2 5 5 20 4.0
3 3 10/1/08 UK F 25 3 5 5 5 2 20 4.0
4 4 10/12/08 UK M 39 3 3 4 NA NA NA NA
5 5 5/1/09 UK F 99 2 2 1 2 1 8 1.6
# recode or change item in variable gender to M::male, F::female
# this is similar to search and replace
leadership$gender <- recode(leadership$gender, #C 
 "M" = "male", "F" = "female") #C 
> leadership
 manager date country gender age q1 q2 q3 q4 q5 total_score mean_score
1 1 10/24/08 US male 32 5 4 5 5 5 24 4.8
2 2 10/28/08 US female 45 3 5 2 5 5 20 4.0
3 3 10/1/08 UK female 25 3 5 5 5 2 20 4.0
4 4 10/12/08 UK male 39 3 3 4 NA NA NA NA
5 5 5/1/09 UK female 99 2 2 1 2 1 8 1.6 
# recode is similar to renaming the row, and rename is for columns
# right to left
leadership <- rename(leadership, ID = "manager", sex = "gender")#D
> leadership
 ID date country sex age q1 q2 q3 q4 q5 total_score mean_score
1 1 10/24/08 US male 32 5 4 5 5 5 24 4.8
2 2 10/28/08 US female 45 3 5 2 5 5 20 4.0
3 3 10/1/08 UK female 25 3 5 5 5 2 20 4.0
4 4 10/12/08 UK male 39 3 3 4 NA NA NA NA
5 5 5/1/09 UK female 99 2 2 1 2 1 8 1.6

leadership <- arrange(leadership, sex, total_score) #E 
> leadership
 ID date country sex age q1 q2 q3 q4 q5 total_score mean_score
1 5 5/1/09 UK female 99 2 2 1 2 1 8 1.6
2 2 10/28/08 US female 45 3 5 2 5 5 20 4.0
3 3 10/1/08 UK female 25 3 5 5 5 2 20 4.0
4 1 10/24/08 US male 32 5 4 5 5 5 24 4.8
5 4 10/12/08 UK male 39 3 3 4 NA NA NA NA
> leadership <- arrange(leadership, sex, desc(total_score)) #E
> leadership
 ID date country sex age q1 q2 q3 q4 q5 total_score mean_score
1 2 10/28/08 US female 45 3 5 2 5 5 20 4.0
2 3 10/1/08 UK female 25 3 5 5 5 2 20 4.0
3 5 5/1/09 UK female 99 2 2 1 2 1 8 1.6
4 1 10/24/08 US male 32 5 4 5 5 5 24 4.8
5 4 10/12/08 UK male 39 3 3 4 NA NA NA NA

> leadership_ratings <- select(leadership, ID, mean_score) #F
> leadership_ratings
 ID mean_score
1 2 4.0
2 3 4.0
3 5 1.6
4 1 4.8
5 4 NA
leadership_men_high <- filter(leadership, #G
 sex == "male" & total_score > 10) #G 
> leadership_men_high <- filter(leadership, #G
+ sex == "male" & total_score > 10) #G
> leadership_men_high
 ID date country sex age q1 q2 q3 q4 q5 total_score mean_score
1 1 10/24/08 US male 32 5 4 5 5 5 24 4.8

filter()#

library('nycflights13')
library('dplyr')
filter(flights, month == 1, day == 1, dep_delay >= 15)

flights[flights$month == 1 & flights$day == 1 & flights$dep_delay >= 15, ]

# this is similar 
subset(flights, month == 1 & day == 1 & dep_delay >= 15)
# better

filter(), with %in%, select specific values in a col

Explaining TCP flows

Fri, 27 Aug 2021 00:00:00 +0000

A few days ago, I wrote a note detailing how to set up a simple TCP client and server using netcat. Today, I have taken things a step further by capturing packets in Wireshark and providing a step-by-step explanation of how the TCP flow works. In the table below, you can find a general overview of this process.

Flow	Packet captured from Wireshark	Explaination
client -[SYN]-> server	Transmission Control Protocol, Src Port: 24491, Dst Port: 5000, Seq: 0, Len: 0 Source Port: 24491 Destination Port: 5000 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 0 (relative sequence number) Sequence Number (raw): 4126488336 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 0 Acknowledgment number (raw): 0 1000 …. = Header Length: 32 bytes (8) Flags: 0x002 (SYN) Window: 65535 [Calculated window size: 65535] Checksum: 0xd6b0 [unverified] [Checksum Status: Unverified] Urgent Pointer: 0	First, client says “hi there, I’d like to connect, here is my number xxxxxxx36 “When client send a SYN packet to server. Wireshark will show you the relative sequence, or ACK number which is 0. But actually, it is a random number .
client <-[SYN,ACK]- server	Transmission Control Protocol, Src Port: 5000, Dst Port: 24491, Seq: 0, Ack: 1, Len: 0 Source Port: 5000 Destination Port: 24491 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 0 (relative sequence number) Sequence Number (raw): 547479085 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 1 (relative ack number) Acknowledgment number (raw): 4126488337 1000 …. = Header Length: 32 bytes (8) Flags: 0x012 (SYN, ACK) Window: 65535 [Calculated window size: 65535] Checksum: 0xd7d0 [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 Options: (12 bytes), Maximum segment size, No-Operation (NOP), Window scale, No-Operation (NOP), No-Operation (NOP), SACK permitted [SEQ/ACK analysis] [Timestamps]	Server responses “oh sure, I’ve received your number xxxxxxx36. And I add one to keep track, so now it is xxxxxxx37. Please take my number xxxxxxx85 “After received the packet from client, server will send its own Sequence number 547479085 and Ackowledgement number.The Acknowledge number is the client’s Sequence number + 1 which is 4126488337
client -[ACK]-> server	Transmission Control Protocol, Src Port: 24491, Dst Port: 5000, Seq: 1, Ack: 1, Len: 0 Source Port: 24491 Destination Port: 5000 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 4126488337 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 1 (relative ack number) Acknowledgment number (raw): 547479086 0101 …. = Header Length: 20 bytes (5) Flags: 0x010 (ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeace [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [SEQ/ACK analysis] [Timestamps]	Client responses “I’ve received your number xxxxxxx85. And I add one to keep track, so now it is xxxxxxx86. We are synced”Client verifies receiving packet from the server by sending ACK (acknowledge) message. The ACK number is server’s Squence number + 1, 547479086
client -[PSH,ACK]-> server	Transmission Control Protocol, Src Port: 24491, Dst Port: 5000, Seq: 1, Ack: 1, Len: 34 Source Port: 24491 Destination Port: 5000 [Stream index: 0] [TCP Segment Len: 34] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 4126488337 [Next Sequence Number: 35 (relative sequence number)] Acknowledgment Number: 1 (relative ack number) Acknowledgment number (raw): 547479086 0101 …. = Header Length: 20 bytes (5) Flags: 0x018 (PSH, ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xd07d [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [SEQ/ACK analysis] [Timestamps] TCP payload (34 bytes)Data (34 bytes)	Now, client starts sending messages with flag PSH meaning “I have packed all the good stuffs, please send it imediately” Also, Next Sequence Number is expected to be 35 because it is sending out 34 bytes payload. ACK number is still 547479086 because it has not received anything from server
client <-[ACK]- server	Transmission Control Protocol, Src Port: 5000, Dst Port: 24491, Seq: 1, Ack: 35, Len: 0 Source Port: 5000 Destination Port: 24491 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 547479086 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 35 (relative ack number) Acknowledgment number (raw): 4126488371 0101 …. = Header Length: 20 bytes (5) Flags: 0x010 (ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeaac [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [SEQ/ACK analysis] [Timestamps]	After receiving the packet, server sends the ACK with previous ACK payload size (34). 4126488337 + 34 = 4126488371
client -[FIN,ACK]-> server	Transmission Control Protocol, Src Port: 24491, Dst Port: 5000, Seq: 35, Ack: 1, Len: 0 Source Port: 24491 Destination Port: 5000 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 35 (relative sequence number) Sequence Number (raw): 4126488371 [Next Sequence Number: 36 (relative sequence number)] Acknowledgment Number: 1 (relative ack number) Acknowledgment number (raw): 547479086 0101 …. = Header Length: 20 bytes (5) Flags: 0x011 (FIN, ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeaab [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [Timestamps]	After sending a note, client terminal is close, so it sends FIN (finish?) and ACK to server. At this time, both Sequence number and ACK number are the same as the above because server did not send anything.
client <-[ACK]- server	Transmission Control Protocol, Src Port: 5000, Dst Port: 24491, Seq: 1, Ack: 36, Len: 0 Source Port: 5000 Destination Port: 24491 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 547479086 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 36 (relative ack number) Acknowledgment number (raw): 4126488372 0101 …. = Header Length: 20 bytes (5) Flags: 0x010 (ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeaab [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [SEQ/ACK analysis] [Timestamps]	After receiving the FIN flag, server response with an ACK message + 1.
client <-[FIN,ACK]- server	Transmission Control Protocol, Src Port: 5000, Dst Port: 24491, Seq: 1, Ack: 36, Len: 0 Source Port: 5000 Destination Port: 24491 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 547479086 [Next Sequence Number: 2 (relative sequence number)] Acknowledgment Number: 36 (relative ack number) Acknowledgment number (raw): 4126488372 0101 …. = Header Length: 20 bytes (5) Flags: 0x011 (FIN, ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeaaa [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [Timestamps]	Now, server closes its portal “hey client, I’m done with you”. Notice, Seq, and ACK are the same as above because server has not received anything from client.c
client -[ACK]- >server	Transmission Control Protocol, Src Port: 24491, Dst Port: 5000, Seq: 36, Ack: 2, Len: 0 Source Port: 24491 Destination Port: 5000 [Stream index: 0] [TCP Segment Len: 0] Sequence Number: 36 (relative sequence number) Sequence Number (raw): 4126488372 [Next Sequence Number: 36 (relative sequence number)] Acknowledgment Number: 2 (relative ack number) Acknowledgment number (raw): 547479087 0101 …. = Header Length: 20 bytes (5) Flags: 0x010 (ACK) Window: 10233 [Calculated window size: 2619648] [Window size scaling factor: 256] Checksum: 0xeaaa [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [SEQ/ACK analysis] [Timestamps]	“Okay server, I have received your farewell letter so I will increase the ACK # to one “. Let reverse engineering, Client’s seq:36, in which we know it has sent 1 byte for SYN, 1 byte for FIN, and the rest are the payload. Client’s ack:2 shows us that it received 1 SYN and 1 FIN from server Also, Server’s seq:1 means it has sent 1 byte for SYN, and probally closes. That is why we don’t see the 2 seq. Server’s ack:36 shows that clent sent 1 SYN, 1 FIN, and 34 bytes of payload.

Quick Note - Decibel dB vs dBm

Tue, 24 Aug 2021 00:00:00 +0000

Many of us have heard about decibel unit in our daily lives, as it can be used to describe the loudness of our speakers, the strength of our antennas, or the signal strength from a transceiver. But what exactly are decibels (dB) and dBm? In this discussion, let’s explore these concepts and expand our understanding.

Explanation#

Deci-bel is ten time of a Bel (10 x Bel)
Bel is named after an inventor Alexander Graham Bell, in Bell Lab.
It is an unit of a ratio on base 10 logarithm scale
Bel is defined as $$X = \log\frac{P2}{P1} $$

TCP/UDP Flow Analysis with Wireshark and Windows Subsystem for Linux

Fri, 20 Aug 2021 00:00:00 +0000

During many of my interviews, I have been asked whether I understood TCP and UDP, and how they differed from each other. While I knew that TCP had an error-checking procedure that made the protocol more reliable but slower than UDP, my understanding was limited. Although I had learned about the detailed structure of these protocols in school, I didn’t have a chance to get hands-on experience with them. However, I later discovered an easy way to explore TCP and UDP packets using Windows Subsystem for Linux (WSL) and WireShark. As a result, I would like to share what I have learned today.

Basic Git commands

Mon, 01 Jan 0001 00:00:00 +0000

Creating and Managing Git Repositories#

If you’re thinking of creating a project for your class, you’ll need to create a Git repository. Here are the steps:

Basic JavaScript Part 1

Mon, 01 Jan 0001 00:00:00 +0000

In this tutorial, I will introduce a few steps to access and edit elements in JavaScript. Mastering and understanding these steps can help you make a simple form, handling submission, and change the outlook of your website.

Table of Contents:

Placeholder for Table of Content (Must not be removed) {:toc}

Edit a text or HTML via jQuery#

This example implement jQuery.

jQuery is a popular JavaScript library that simplifies DOM manipulation and event handling in web development. One of its key strengths is its ability to quickly and easily edit the content of text or HTML elements on a web page.

Using Ajax, Xhttp, Fetch, and Axios to get page content

Mon, 01 Jan 0001 00:00:00 +0000

Axios is a popular JavaScript library used for making HTTP requests from a browser or Node.js. It provides a simple and elegant way to make asynchronous HTTP requests to a server, and handle responses in a clean and efficient manner.

Fetch is a built-in web API in modern browsers that allows you to make HTTP requests to a server and retrieve data in a simple and straightforward way. It provides an alternative to the traditional XMLHttpRequest (XHR) API, and is designed to be easy to use and flexible.