https://limingjie.github.io/ Recent content on Mingjie Li Hugo -- gohugo.io en-us Tue, 28 Feb 2023 00:00:00 +0800 https://limingjie.github.io/posts/2023-02-28-op-amps-for-everyone-notes/ Tue, 28 Feb 2023 00:00:00 +0800 https://limingjie.github.io/posts/2023-02-28-op-amps-for-everyone-notes/ Chapter 2 - Development of the Ideal Op Amp Equations Ideal Op Amp Parameter Value $I_{\text{IN}}$ - Input current 0 $V_{\text{OS}}$ - Input offset voltage 0 $Z_{\text{IN}}$ - Input impedance $\infin$ $Z_{\text{OUT}}$ - Outage impedance 0 $a$ - Gain $\infin$ From Wikipedia - Operational Amplifier: Infinite open-loop gain $G = v_{\text{out}} / v_{\text{in}}$ Infinite input impedance $R_{\text{in}}$, and so zero input current Zero input offset voltage Infinite output voltage range Infinite bandwidth with zero phase shift and infinite slew rate Zero output impedance $R_{\text{out}}$, and so infinite output current range Zero noise Infinite common-mode rejection ratio (CMRR) Infinite power supply rejection ratio. https://limingjie.github.io/utils/ Tue, 28 Feb 2023 00:00:00 +0800 https://limingjie.github.io/utils/ RGB Colors https://limingjie.github.io/posts/2022-09-27-ch552-development/ Wed, 28 Sep 2022 00:00:00 +0800 https://limingjie.github.io/posts/2022-09-27-ch552-development/ CH552G/CH554G Pinout (Get original SVG image from GitHub) # Pin Timer SPI PWM UART Timer Interrupt Touch USB ADC From Datasheet 1 P3.2 TXD1_ INT0 VBUS1 AIN3 P3.2/TXD1_/INT0/VBUS1/AIN3 2 P1.4 T2_/CAP1_ SCS TIN2 UCC1 AIN1 P1.4/T2_/CAP1_/SCS/TIN2/UCC1/AIN1 3 P1.5 MOSI PWM1 TIN3 UCC2 AIN2 P1.5/MOSI/PWM1/TIN3/UCC2/AIN2 4 P1.6 MISO RXD1 TIN4 P1.6/MISO/RXD1/TIN4 5 P1.7 SCK TXD1 TIN5 P1.7/SCK/TXD1/TIN5 6 RST T2EX_/CAP2_ RST/T2EX_/CAP2_ 7 P3.1 PWM2_ TXD P3.1/PWM2_/TXD 8 P3.0 PWM1_ RXD P3.0/PWM1_/RXD 9 P1. https://limingjie.github.io/posts/2021-12-28-convert-jupyter-notebook-with-cjk-to-pdf-on-macos/ Tue, 28 Dec 2021 12:59:00 +0800 https://limingjie.github.io/posts/2021-12-28-convert-jupyter-notebook-with-cjk-to-pdf-on-macos/ Install Dependencies Follow nbconvert Installation Guide to install dependencies. 1 2 3 pip install nbconvert pip install pandoc brew install mactex Install CJK Font Use system font or install any CJK font. I recommend Sarasa Gothic (更纱黑体 / 更紗黑體 / 更紗ゴシック / 사라사고딕). 1 brew install font-sarasa-gothic Convert the Notebook to PDF Convert the notebook to tex 1 jupyter nbconvert --to latex notebook-to-convert.ipynb Modify the tex file to add CJK package and set CJK font https://limingjie.github.io/posts/2021-03-02-logic-gate-learning-kit/ Tue, 02 Mar 2021 23:00:00 +0800 https://limingjie.github.io/posts/2021-03-02-logic-gate-learning-kit/ Build for my 5-year-old son to learn logic gates. Logic Gate Learning Kit PCB Logic Gate Learning Kit Cheat Sheet PCB BOM ID Name Comment Footprint Quantity 1 BATTERY 2xAA Battery BATTERY-HOLDER-2AA 1 2 HDR-F-2.54_1x2 Output Pin Sockets HDR-F-2.54_1X2 12 3 HDR-F-2.54_2x2 A/B/C Pin Sockets HDR-F-2.54_2X2 3 4 HDR-F-2.54_2x8 Fixed Pin Sockets HDR-F-2.54_2X8 2 5 HDR-M-2.54_1x1 Input Pin Headers HDR-M-2.54_1X1 25 6 LED LED LED_1206 40 7 R100k Pull Down Resistor R_0805 22 8 R1K Resistor for LED R_0805 40 9 SN74LVC1G00DBVR NAND Gate SOT-23-5 2 10 SN74LVC1G02DBVR NOR Gate SOT-23-5 2 11 SN74LVC1G04DBVR NOT Gate SOT-23-5 2 12 SN74LVC1G08DBVR AND Gate SOT-23-5 2 13 SN74LVC1G32DBVR OR Gate SOT-23-5 2 14 SN74LVC1G86DBVR XOR Gate SOT-23-5 2 15 SS12D00G3 Switch SLIDE_MINI_SWITCH 4 Clone The Project Logic Gate Learning Kit on GitHub Logic Gate Learning Kit on EasyEDA License This work is licensed under a Creative Commons Attribution-NonCommercial 4. https://limingjie.github.io/posts/2020-02-24-multiply-big-numbers/ Mon, 24 Feb 2020 23:00:00 +0800 https://limingjie.github.io/posts/2020-02-24-multiply-big-numbers/ Multiply Strings I answered this LeetCode question many years ago and got a successful submission with a not too bad score. Some code like this, I tried to make it easy to understand, well it might sacrifice some performance. The code takes less than 1s to calculate 10,000! on a MBP 2017 and nearly 100s to calculate 100,000!. Bravo! 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 #include <algorithm> #include <iostream> #include <iterator> #include <string> #include <vector> std::string multiply(std::string a, std::string b) { size_t size_a = a. https://limingjie.github.io/posts/2019-07-18-knuth-shuffle/ Thu, 18 Jul 2019 20:05:00 +0800 https://limingjie.github.io/posts/2019-07-18-knuth-shuffle/ Test of Randomness using a fixed seed. A fixed seed will generate fixed sequence of random numbers. shuffle.go 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 package shuffle import ( "math/rand" ) // Shuffle - Knuth Shuffle // https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle // > -- To shuffle an array a of n elements (indices 0. https://limingjie.github.io/posts/2019-05-29-katex-pinyin/ Wed, 29 May 2019 23:50:59 +0800 https://limingjie.github.io/posts/2019-05-29-katex-pinyin/ Use \atop $$ \def\py#1#2{\text{\scriptsize{#2}}\atop\text{\;#1\;}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} \\~\\ {\py{关}{gu\=an}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} {\py{鸠}{ji\=u}} {\py{，}{}} {\py{在}{z\`ai}} {\py{河}{h\'e}} {\py{之}{zh\=\i}} {\py{洲}{zh\=ou}} {\py{。}{}} \\~\\ {\py{窈}{y\v{a}o}} {\py{窕}{ti\v{a}o}} {\py{淑}{sh\=u}} {\py{女}{n\v{\"u}}} {\py{，}{}} {\py{君}{j\=un}} {\py{子}{z\v\i}} {\py{好}{h\v{a}o}} {\py{逑}{qi\'u}} {\py{。}{}} $$ 1 2 3 4 5 6 7 8 9 10 \def\py#1#2{\text{\scriptsize{#2}}\atop\text{\;#1\;}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} \\~\\ {\py{关}{gu\=an}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} {\py{鸠}{ji\=u}} {\py{，}{}} {\py{在}{z\`ai}} {\py{河}{h\'e}} {\py{之}{zh\=\i}} {\py{洲}{zh\=ou}} {\py{。}{}} \\~\\ {\py{窈}{y\v{a}o}} {\py{窕}{ti\v{a}o}} {\py{淑}{sh\=u}} {\py{女}{n\v{\"u}}} {\py{，}{}} {\py{君}{j\=un}} {\py{子}{z\v\i}} {\py{好}{h\v{a}o}} {\py{逑}{qi\'u}} {\py{。}{}} Use \overset $$ \def\py#1#2{\overset{\text{#2}}{\text{\;#1\;}}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} \\ {\py{关}{gu\=an}} {\py{关}{gu\=an}} {\py{雎}{j\=u}} {\py{鸠}{ji\=u}} ， {\py{在}{z\`ai}} {\py{河}{h\'e}} {\py{之}{zh\=\i}} {\py{洲}{zh\=ou}} 。 \\ {\py{窈}{y\v{a}o}} {\py{窕}{ti\v{a}o}} {\py{淑}{sh\=u}} {\py{女}{n\v{\" https://limingjie.github.io/posts/2019-05-28-render-tex-in-hugo/ Wed, 29 May 2019 00:30:00 +0800 https://limingjie.github.io/posts/2019-05-28-render-tex-in-hugo/ Recently, I started to think about learning $\TeX$, adding $\TeX$ support to blog looks like a good start for me. It took me quite some time to figure out all the culprits of embedding $\TeX$ in markdown. I hope this blog could save you some time before starting writing in $\TeX$. Note: Some contents in this post is outdated. Hugo markdown engine moved from Blackfriday to Goldmark. Required Components The default Blackfriday markdown engine. https://limingjie.github.io/posts/2019-05-27-algorithm-summary-threshold/ Sun, 26 May 2019 22:00:00 +0800 https://limingjie.github.io/posts/2019-05-27-algorithm-summary-threshold/ Question Given an array of integers $A (a_i \geq 0, i \in [0, n])$ and a threshold $T$. If $\sum_{i = 0}^n a_i > T$, find an integer $t$, for $a_i > t (i \in [0, n]) \to a_i = t$. Find the largest $t$ which makes $\sum_{i = 0}^n a_i \leq T$. For Example, $A = [30, 20, 10, 50, 40],,,T = 127$. Expecting $t = 33$. Answer ArraySummaryThreshold.go https://limingjie.github.io/posts/2019-05-25-golang-closure-exercise/ Sat, 25 May 2019 15:00:00 +0800 https://limingjie.github.io/posts/2019-05-25-golang-closure-exercise/ I always had a question, if Golang does not have the static variable, how could it gracefully handle long lifetime variables except using global variables? Until last night, I saw this Exercise: Fibonacci closure in A tour of Go. I have to admit I am not a fan of closure, sometimes it makes easy logic complex. But it is still great for learning. Exercise: Fibonacci closure Let’s have some fun with functions. https://limingjie.github.io/posts/2019-05-01-my-mechanical-keyboards/ Wed, 01 May 2019 00:00:00 +0800 https://limingjie.github.io/posts/2019-05-01-my-mechanical-keyboards/ My very first impression of a mechanical keyboard is a clunky ISO layout IBM keyboard on which I learned touch typing, I can still remember it was full of noise like rusty sprints. Then suddenly, the whole world is dominated by membrane keyboards for its low cost and quiet experience. As a fan of keyboards and mice. I owned Logitech mice M505, M525, and M545, guess what? I only paid the first one, they kept broken within the warranty and got replaced. https://limingjie.github.io/posts/2019-04-10-m5stack-traffic-light/ Wed, 10 Apr 2019 22:10:00 +0800 https://limingjie.github.io/posts/2019-04-10-m5stack-traffic-light/ A traffic light toy build on M5Stack. Find the source code on GitHub. Customize The Traffic Light Find the traffic light sequence definition in TrafficLight.ino. Customize the sequence in lights array. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Traffic light struct typedef struct { int color_index; // 1 - Red, 2 - Yellow, 3 - Green bool blink; unsigned long interval; // milliseconds } Traffic_Light; // Traffic light sequences Traffic_Light lights[] = { {3, false, 99999}, {3, true, 10999}, {2, true, 10999}, {1, false, 30999}, {1, true, 10999}}; https://limingjie.github.io/about/ Mon, 01 Jan 0001 00:00:00 +0000 https://limingjie.github.io/about/ Experience Everbridge Senior Software Engineering Manager Apr 2022 – Present · Beijing, China Software Engineering Manager Aug 2017 – Apr 2022 · 4 yrs 9 mos · Beijing, China Oracle Software Development Manager Dec 2015 – Aug 2017 · 1 yr 9 mos · Beijing, China Principal Software Engineer Dec 2014 – Dec 2015 · 1 yr 1 mo · Beijing, China Senior Software Engineer Sep 2012 – Nov 2014 · 2 yrs 3 mos · Beijing, China Software Engineer Mar 2011 – Aug 2012 · 1 yr 6 mos · Beijing, China IBM IT Specialist Mar 2006 – Mar 2011 · 5 yrs 1 mo · Dalian, China Certifications PMI Agile Certified Practitioner (PMI-ACP)® · Project Management Institute Issued Dec 2018 · Expires Dec 2024 PMI Issued ACP Badge Project Management Professional (PMP)® · Project Management Institute Issued Mar 2018 · Expires Mar 2024 PMI Issued PMP Badge Patent US10152590B2 - Implementing a WebSocket server to circumvent access controls, by a web browser, on a web application Issued Dec 11, 2018 Google Patents - US10152590B2