Bumblebee: turn browser sessions to code

BUMBLEBEE: TURN BROWSER SESSIONS TO CODE

+ +

02 APRIL 2025

+ +
+ +

Bumblebee is a web browser that turns browser sessions into C# scripts. Its +objective is to eliminate the need for authoring scripts for testing, web +scraping, and other browser automation tasks.

+ +

Bumblebee is a Windows Forms application written in C#. The rendering of web +content is handled by the embedded Microsoft Edge browser (via WebView). The +text editor on the right is Scintilla.NET. It +enables users to override the script at any point during the session. There are +application settings that let users debounce events, ignore hidden elements +and scripts, and more.

+ +

Unfortunately, I can’t share the source code for Bumblebee. I developed it for +an employer. Hence, the software is proprietary.

+ +

by W. D. Sadeep Madurange

Bumblebee is a web browser that turns browser sessions into C# scripts. Its -objective is to eliminate the need for authoring scripts for testing, web -scraping, and other browser automation tasks.

Bumblebee is a Windows Forms application written in C#. The rendering of web -content is handled by the embedded Microsoft Edge browser (via WebView). The -text editor on the right is Scintilla.NET. It -enables users to override the script at any point during the session. There are -application settings that let users debounce events, ignore hidden elements -and scripts, and more.

Unfortunately, I can’t share the source code for Bumblebee. I developed it for -an employer. Hence, the software is proprietary.

UNIX FOR THE DESKTOP

+ +

21 SEPTEMBER 2025

+ +
+ +

The year 2020 transformed my personal computing experience. In March 2020, I +stumbled upon Arch Linux and discovered that I could customize my desktop +environment to look and work any way I liked. I exercised that newfound freedom +to create a Matrix-themed setup:

+ +

Arch Linux

+ +

The system employs the X display server and the i3 window manager. The terminal +emulator used is Urxvt. The translucent effect is achieved with the help of the +Xcompmgr compositor. This sort of setup was popular among minimalist Linux +users.

+ +

In February 2024, I switched to an OpenBSD system with Xenocara (the OpenBSD +build of X display server) as the display server and i3 as the window manager:

+ +

OpenBSD i3

+ +

Unlike Linux, OpenBSD includes a coherent desktop environment out of the box. +Except for the window manager, for which I prefer a tiling one, I’m now using +the default OpenBSD setup. For the window manager, I use dwm from the Suckless +team.

+ +

Files: dotfiles.tar.gz

+ +

by Wickramage Don Sadeep Madurange

The year 2020 transformed my personal computing experience. In March 2020, I -stumbled upon Arch Linux and discovered that I could customize my desktop -environment to look and work any way I liked. I exercised that newfound freedom -to create a Matrix-themed setup:

The system employs the X display server and the i3 window manager. The terminal -emulator used is Urxvt. The translucent effect is achieved with the help of the -Xcompmgr compositor. This sort of setup was popular among minimalist Linux -users.

In February 2024, I switched to an OpenBSD system with Xenocara (the OpenBSD -build of X display server) as the display server and i3 as the window manager:

Unlike Linux, OpenBSD includes a coherent desktop environment out of the box. -Except for the window manager, for which I prefer a tiling one, I’m now using -the default OpenBSD setup. For the window manager, I use dwm from the Suckless -team.

ETLAS: E-PAPER DISPLAY FOR NEWS, STOCKS, AND THE WEATHER

+ +

05 SEPTEMBER 2024

+ +
+ +

Etlas is a news, stock market, and weather tracker powered by an ESP32 NodeMCU +D1, featuring a 7.5-inch Waveshare e-paper display and a DHT22 sensor module.

+ + + + + + +

+ +

The top left panel displays the end-of-day stock prices from the Polygon.io API, relayed through my own +FastCGI-wrapped Flask app hosted on a VPS. The stock symbols can be configured +through the Flask app’s application settings. The server.fcgi script enclosed +in the tarball at the end of the page contains the Flask app.

+ +

The following diagram outlines this system architecture.

+ +

architecture

+ +

Unlike my e-reader, which worked with raster images, +Etlas downloads time series data as CSV and computes the price curves on the +ESP32.

+ +

The more prominent panel on the right of the e-paper display shows local +(Singapore) and world news from the Channel News Asia RSS feed. The MCU +downloads and parses XML data from the RSS feed directly before rendering it to +the display. Although I did it this way to avoid writing server code, it limits +the feeds from which Etlas can receive data. In a future version, I will relay +the RSS feed through a server (like the stock prices) to make it more flexible.

+ +

The bottom panels (middle and right) display the temperature and relative +humidity from a DHT22 sensor. The DHT22 driver, arguably the most interesting +part of the software, reads real-time sensor data by comparing relative pulse +widths. The pulses themselves are too quick for the ESP32 to reliably measure +directly. I ported this +implementation for ESP8266 modules to my ESP32. All credit for the algorithm +belongs to them.

+ +

Much of the heavy lifting of acquiring, interpreting, and rendering data from +different data sources is performed on the microcontroller using less than 512 +KB of memory. The embedded software that makes that possible is written in C +using the ESP-IDF v5.2.1. My e-paper display driver is a port of Waveshare examples for Arduino +and STM32 platforms.

+ +

I’ve been using Etlas daily (for a couple of hours on weekdays and all day on +weekends) since August 2024. As of October 2025, it’s been running reliably for +over a year. If you are interested in an e-paper display like this, drop me an +email at the address on my home page.

+ +

Files: source.tar.gz

+ +

by W. D. Sadeep Madurange

Etlas is a news, stock market, and weather tracker powered by an ESP32 NodeMCU -D1, featuring a 7.5-inch Waveshare e-paper display and a DHT22 sensor module.

The top left panel displays the end-of-day stock prices from the Polygon.io API, relayed through my own -FastCGI-wrapped Flask app hosted on a VPS. The stock symbols can be configured -through the Flask app’s application settings. The server.fcgi script enclosed -in the tarball at the end of the page contains the Flask app.

Unlike my e-reader, which worked with raster images, -Etlas downloads time series data as CSV and computes the price curves on the -ESP32.

The more prominent panel on the right of the e-paper display shows local -(Singapore) and world news from the Channel News Asia RSS feed. The MCU -downloads and parses XML data from the RSS feed directly before rendering it to -the display. Although I did it this way to avoid writing server code, it limits -the feeds from which Etlas can receive data. In a future version, I will relay -the RSS feed through a server (like the stock prices) to make it more flexible.

The bottom panels (middle and right) display the temperature and relative -humidity from a DHT22 sensor. The DHT22 driver, arguably the most interesting -part of the software, reads real-time sensor data by comparing relative pulse -widths. The pulses themselves are too quick for the ESP32 to reliably measure -directly. I ported this -implementation for ESP8266 modules to my ESP32. All credit for the algorithm -belongs to them.

Much of the heavy lifting of acquiring, interpreting, and rendering data from -different data sources is performed on the microcontroller using less than 512 -KB of memory. The embedded software that makes that possible is written in C -using the ESP-IDF v5.2.1. My e-paper display driver is a port of Waveshare examples for Arduino -and STM32 platforms.

I’ve been using Etlas daily (for a couple of hours on weekdays and all day on -weekends) since August 2024. As of October 2025, it’s been running reliably for -over a year. If you are interested in an e-paper display like this, drop me an -email at the address on my home page.

FINGERPRINT DOOR LOCK

+ +

03 OCTOBER 2025

+ +
+ +

This project features a fingerprint door lock powered by an ATmega328P +microcontroller.

+ +

Overview

+ +

The lock comprises three subsystems: the ATmega328P, an R503 fingerprint +sensor, and an FS5106B high-torque servo. The sensor mounted on the front +surface of the door enables users to unlock it from the outside. The servo is +attached to the interior door knob. The MCU must be installed at the back of +the door to prevent unauthorized users from tampering with it.

+ +

When no one is interacting with the lock, the MCU is in deep sleep. The sensor +and the servo each draw 13.8 mA and 4.6 mA of quiescent currents. To prevent +this idle current draw, the MCU employs MOSFETs to cut off power to them before +entering deep sleep. Doing so is crucial for conserving the battery.

+ +

Without power, the sensor remains in a low-power state, drawing approximately +2.9 μA through a separate power rail. When a finger comes into contact with the +sensor, the sensor triggers a pin change interrupt, waking up the MCU. The MCU +activates a MOSFET, which in turn activates the sensor. Over UART, the MCU +unlocks the sensor and issues commands to scan and match the fingerprint.

+ +

If the fingerprint matches an enrolled fingerprint, the MCU activates the blue +LED on the sensor, turns on the MOSFET connected to the servo, and sends a PWM +signal to the servo to unlock the door. Otherwise, the MCU activates the red +LED on the sensor. Finally, the MCU deactivates the MOSFETS and goes back to +sleep.

+ +

Embedded software

+ +

The embedded software, written in C with the help of the AVR toolchain, +includes a driver for the sensor, servo control routines, and a battery +monitoring system.

+ +

In addition to controlling the sensor and the servo, the program strives to +maintain precise control over the sleep mode, as well as when the peripherals +are activated and for how long they remain active. I thoroughly enjoyed writing +the embedded software. There’s something magical about being able to alter the +physical world around you by uttering a few lines of C code.

+ +

The source code of the project, which includes a driver for the R503 +fingerprint sensor module, is enclosed in the tarball linked at the end of the +page.

+ +

The circuit board

+ +

For this project, I designed a custom PCB and had it fabricated by JLCPCB. Like +the software, the circuit is chiefly concerned with optimizing power +consumption and extending battery life.

+ + + + + + + + + +

+ +	+ +
+ +

+ +

To that end, the principal components of the circuit are the 2N7000 and +NDP6020P field-effect transistors. They switch power electronically to the +servo and the fingerprint sensor, the two most power-hungry parts of the +circuit. The two MP1584EN buck converters play an axial role in efficiently +regulating power to the MCU and the sensor.

+ +

The ATmega328P typically operates at 5 V with a 16 MHz crystal oscillator. To +further reduce power consumption, I modified the ATmega328P’s fuses to run at +3.3 V with an 8 MHz crystal oscillator.

+ +

The bottom right area of the PCB isolates the power supply of the servo from +the rest of the circuit. This shields components such as the MCU from the +servo’s high current draw, which can exceed 1 A. The IN4007 diode in slot U2 +serves as a flyback diode, protecting the MOSFET from reverse currents +generated by the servo.

+ +

Lastly, the 56 kΩ and 10 kΩ resistors in slots R10 and R11 form a voltage +divider circuit. Its output is fed to the ADC of the MCU, which measures the +supply voltage by comparing it to the internal bandgap reference voltage.

+ +

Epilogue

+ +

This project began nearly a year ago when I attempted to unlock our door +wirelessly by writing to the UART ports of two MCUs connected to inexpensive +433 MHz RF transceivers, as if there were an invisible wire between them. +Although I failed, it led me down a rabbit hole of RF communications, MOSFETs, +PCB design, and low-power circuits.

+ +

During the project, I reinvented the wheel many times. I implemented a +low-level network stack using only RF modules and an 8-bit microcontroller, +designed my first PCB, and developed drivers from scratch. The project was far +from a smooth sail. Bad electrical connections, soldering, desoldering, and the +heartache of purchasing the wrong parts were routine. It was a long but +rewarding journey from the messy breadboard to the shiny PCB.

+ +

Files: source.tar.gz, gerber.zip

+ +

by W. D. Sadeep Madurange

This project features a fingerprint door lock powered by an ATmega328P -microcontroller.

Overview

The lock comprises three subsystems: the ATmega328P, an R503 fingerprint -sensor, and an FS5106B high-torque servo. The sensor mounted on the front -surface of the door enables users to unlock it from the outside. The servo is -attached to the interior door knob. The MCU must be installed at the back of -the door to prevent unauthorized users from tampering with it.

When no one is interacting with the lock, the MCU is in deep sleep. The sensor -and the servo each draw 13.8 mA and 4.6 mA of quiescent currents. To prevent -this idle current draw, the MCU employs MOSFETs to cut off power to them before -entering deep sleep. Doing so is crucial for conserving the battery.

Without power, the sensor remains in a low-power state, drawing approximately -2.9 μA through a separate power rail. When a finger comes into contact with the -sensor, the sensor triggers a pin change interrupt, waking up the MCU. The MCU -activates a MOSFET, which in turn activates the sensor. Over UART, the MCU -unlocks the sensor and issues commands to scan and match the fingerprint.

If the fingerprint matches an enrolled fingerprint, the MCU activates the blue -LED on the sensor, turns on the MOSFET connected to the servo, and sends a PWM -signal to the servo to unlock the door. Otherwise, the MCU activates the red -LED on the sensor. Finally, the MCU deactivates the MOSFETS and goes back to -sleep.

Embedded software

The embedded software, written in C with the help of the AVR toolchain, -includes a driver for the sensor, servo control routines, and a battery -monitoring system.

In addition to controlling the sensor and the servo, the program strives to -maintain precise control over the sleep mode, as well as when the peripherals -are activated and for how long they remain active. I thoroughly enjoyed writing -the embedded software. There’s something magical about being able to alter the -physical world around you by uttering a few lines of C code.

The source code of the project, which includes a driver for the R503 -fingerprint sensor module, is enclosed in the tarball linked at the end of the -page.

The circuit board

For this project, I designed a custom PCB and had it fabricated by JLCPCB. Like -the software, the circuit is chiefly concerned with optimizing power -consumption and extending battery life.

To that end, the principal components of the circuit are the 2N7000 and -NDP6020P field-effect transistors. They switch power electronically to the -servo and the fingerprint sensor, the two most power-hungry parts of the -circuit. The two MP1584EN buck converters play an axial role in efficiently -regulating power to the MCU and the sensor.

The ATmega328P typically operates at 5 V with a 16 MHz crystal oscillator. To -further reduce power consumption, I modified the ATmega328P’s fuses to run at -3.3 V with an 8 MHz crystal oscillator.

The bottom right area of the PCB isolates the power supply of the servo from -the rest of the circuit. This shields components such as the MCU from the -servo’s high current draw, which can exceed 1 A. The IN4007 diode in slot U2 -serves as a flyback diode, protecting the MOSFET from reverse currents -generated by the servo.

Lastly, the 56 kΩ and 10 kΩ resistors in slots R10 and R11 form a voltage -divider circuit. Its output is fed to the ADC of the MCU, which measures the -supply voltage by comparing it to the internal bandgap reference voltage.

Epilogue

This project began nearly a year ago when I attempted to unlock our door -wirelessly by writing to the UART ports of two MCUs connected to inexpensive -433 MHz RF transceivers, as if there were an invisible wire between them. -Although I failed, it led me down a rabbit hole of RF communications, MOSFETs, -PCB design, and low-power circuits.

During the project, I reinvented the wheel many times. I implemented a -low-level network stack using only RF modules and an 8-bit microcontroller, -designed my first PCB, and developed drivers from scratch. The project was far -from a smooth sail. Bad electrical connections, soldering, desoldering, and the -heartache of purchasing the wrong parts were routine. It was a long but -rewarding journey from the messy breadboard to the shiny PCB.

The Matrix digital rain for Unix terminals

The Matrix digital rain

Prototype fingerprint door lock

Fingerprint door lock

THE MATRIX DIGITAL RAIN

+ +

12 JANUARY 2024

+ +
+ +

The famous digital rain from the movie The Matrix implemented in C for +the Unix terminal without using any GUI/TUI kits:

+ +

Domsson’s Fakesteak inspired +this project. I added the following features while trying to keep the original +project’s simplicity intact as much as possible:

+ +

Customize the rain color to match the theme of the setup.
Support for UTF-32 characters.
The ghosting effect of old monochrome displays.
The rain more closely resembles the original from the first movie.

+ +

To use them, you need a terminal emulator that supports 24-bit RGB colors and +Unicode characters.

+ +

The background, head, and tail colors of the rain can be configured via +COLOR_BG_*, COLOR_HD_*, and COLOR_TL_* settings. The UNICODE_MIN and +UNICODE_MAX values control the character set used for the rain. For instance, +use 0x30A1 and 0x30F6 for Katakana:

+ +

Happy ricing!

+ +

Files: source.tar.gz

+ +

by W. D. Sadeep Madurange

The famous digital rain from the movie The Matrix implemented in C for -the Unix terminal without using any GUI/TUI kits:

Domsson’s Fakesteak inspired -this project. I added the following features while trying to keep the original -project’s simplicity intact as much as possible:

To use them, you need a terminal emulator that supports 24-bit RGB colors and -Unicode characters.

The background, head, and tail colors of the rain can be configured via -COLOR_BG_*, COLOR_HD_*, and COLOR_TL_* settings. The UNICODE_MIN and -UNICODE_MAX values control the character set used for the rain. For instance, -use 0x30A1 and 0x30F6 for Katakana: