Software Development

696 Articles

The GitHub Silverware Drawer Dilemma, Or: Finding Active Repository Forks

January 8, 2023 by 11 Comments

An fortunate reality of GitHub and similar sites is that projects that are abandoned by the maintainer are often continued by someone else who forked the project. Unfortunately, the ease of forking also means that GitHub projects tend to have a lot of forks, with the popular projects having hundreds of them. Since GitHub has elected to not provide a way to filter or sort these forks, finding the most active fork can be rather harrowing.

In addition, a popular project’s dead repository tends to score higher in search results than replacement forks. For these particular situations a couple of very useful websites and browser add-ons have been developed. The Lovely Forks add-on by [Utkarsh Upadhyay] seeks to insert information on forks that are notable or newer than the repository one is looking at.

Meanwhile, the Active Forks project by [Samar Dhwoj Acharya] provides a sortable list of project forks when provided with a GitHub repository name. This helps enormously when trying to find the freshest forks in a whole list. This is similar to the Useful Forks project that provides a web-based interface in addition to a Chrome extension. Do note that these queries will count towards the GitHub API rate-limits, so you may need to add an access token.

It’s a shame that GitHub doesn’t offer such functionality by default, but thanks to these projects the times of clicking through a hundred forks to find the freshest one is at least over. For now.

Encoding NTSC With Your Hands Tied

December 25, 2022 by 10 Comments

Generally, when trying to implement some protocol, you are constrained by your hardware and time. But for someone like [EMMIR], that’s not enough. For example, NTSC-CRT is a video signal encoding/decoding simulator with no hardware acceleration, floating point math, or third-party libraries. Just basic C.

While NTSC has officially gone dark in America, people still make their own ATTiny-powered transmitters. NTSC is a bit of a strange standard and is sometimes referred to as never-twice-the-same color, but it does produce a distinct look.

That look is what [EMMIR] was going for. It encodes a message in a ppm format into NTSC and then back in ppm with some configurable noise. It can do this in real-time as an effect in [EMMIR’s] engine or on a rendered image via a CLI. It looks incredible, and there’s something very satisfying. There’s a video after the break showing off the effect. The code is pretty short and easy to read.

Continue reading “Encoding NTSC With Your Hands Tied” →

Squeezing GIFs Into Even Tighter Spaces

December 21, 2022 by 6 Comments

Showing images on a TFT or OLED display with a small AVR microcontroller can be a challenge as it requires significant storage space. One solution is to compress the images, but then you need more RAM to decompress it, and that’s a whole other problem. [David Johnson-Davies] of Technoblogy couldn’t find a GIF decoder that fit his needs, so he started writing his own.

We had previously seen a minimal GIF decoder aimed at a Cortex-M0+ that required 24 K of RAM, but this technique is running on an AVR with just 12 K of RAM. Along the way, [David] uses little tricks to shave down the requirements. Since the TFT he targets is a 5-6-5 color space, those 3-byte colors become 2 bytes. The LZW lookup table is encoded as 12-bit pointers to earlier entries plus an additional pixel. However, these savings come at a cost. Animated, local color tables, transparency, interlacing, or GIF87a formatted images aren’t supported. But he ports it over to the PyBadge, which is ATSAMD51 based.

[David] provides some sample code to display a GIF from program memory and an SD card. All the code is on GitHub under a CC By 4.0 license.

After 40 Years, Adobe Releases PostScript Source V0.10 For Posterity

December 13, 2022 by 28 Comments

Celebrating their 40th anniversary, Adobe released the source code of PostScript v0.10 to the Computer History Museum. But before you ask, we tried and it won’t compile with GCC out of the box – it’s missing at least except.h, but we’d bet you can hack around it with a little dedication.

PostScript is the precursor to PDF, and at the time it was revolutionary. Coming out of Xerox’s PARC, the idea was to create device- and resolution-independent documents where all the characters, symbols, and graphics are described by their shapes instead of bitmaps. PostScript’s secret sauce was in how it went back to a pixel-based representation for end use on monitors or printers. It’s no exaggeration to say that this ended up revolutionizing the print industry, and it makes sense in the CHM’s collection.

Still, on the trade-secret front, you shouldn’t get too excited. Apparently the code released here only includes a first-draft version of Adobe’s font hinting algos, as evidenced by the early version number. Nonetheless, you’re free to dig into pretty readable C. For instance, vm.c contains the virtual machine that implements PostScript’s almost Forth-like language.

Of course, if you’d just like to mess around with PostScript, downloading a modern open-source interpreter like GhostScript probably makes a lot more sense. Even so, it’s fun to see the original codebase where it all started.

Push ESP32 Over The Air Updates From GitHub

December 13, 2022 by 21 Comments

Let’s say you’re working on an ESP32 project to send off to your grandma; something she can just plug in and it will start automatically monitoring her plant’s water levels. But you discover a critical flaw in the firmware and need to update it. Does she send it back? Do you walk her through dropping the update via the Arduino IDE OTA? The easiest way would be to plan and use something like esp_ghota, an OTA framework by [Justin Hammond].

OTA (Over-The-Air) updates are a fantastic feature of the ESP32, and we’ve covered libraries that make it easy. But compared to those earlier projects, esp_ghota takes a different approach. Rather than hosting a web server where someone can drop a binary, it looks at GitHub releases. [Justin] had to include a streaming JSON parser, as GitHub API responses tend to be beefy. The workflow is straightforward, push a new commit to your main branch on GitHub, and the action will trigger, building a few different versions. Your little plant watering reminder at your grandma’s will check every so often to see if a new version has been pushed and can update with rollback on littlefs, fatfs, and spiffs filesystems.

It’s an incredible project that we suspect will be very useful for many folks to update their projects. [Justin] even includes an example GitHub action and a sample ESP32 project.

Flipper Zero Hacker Tool Gets UI Editor For Custom Apps

December 10, 2022 by 12 Comments

[Mikhail] released a handy GUI editor/generator tool for the Flipper Zero multipurpose hacker tool, making layouts and UI elements much easier and more intuitive to craft up.

Those who decide to delve into rolling their own applications or add-ons will find this a handy resource, especially as it generates the necessary code for the visual elements. It’s not limited to placing icons, either. Boxes, lines, dots, text, and more can be freely laid out to get things looking just right.

To use it, simply drag and drop icons of various sizes into the screen area. Non-icon UI elements like frames, lines, text, and others can be placed with a click using the buttons. To move elements around, click the SELECT button first, then drag things as needed. To fine-tune positioning (or change the text of a string) a selected element’s properties can be accessed and modified to the right of the simulated screen. When things look good, switch to the CODE tab and copy away to use it in your Flipper application.

Unfamiliar with the Flipper Zero? It’s a kind of wireless multitool; a deeply interesting device intended to make wireless exploration and experimentation as accessible as its dolphin mascot is adorable.

Nucleo-F429ZI development board with STM32F429 microcontroller

Epic Guide To Bare-Metal STM32 Programming

December 5, 2022 by 31 Comments

[Sergey Lyubka] put together this epic guide for bare-metal microcontroller programming.  While the general concepts should be applicable to most any microcontroller, [Sergey]s examples specifically relate to the Nucleo-F429ZI development board featuring the ARM-based STM32F429 microcontroller.

In the realm of computer systems, bare-metal programming most often refers to programming the processor without an intervening operating system. This generally applies to programming BIOS, hardware drivers, communication drivers, elements of the operating system, and so forth. Even in the world of embedded programming, were things are generally quite low-level (close to the metal), we’ve grown accustomed to a good amount of hardware abstraction. For example, we often start projects already standing on the shoulders of various libraries, boot loaders, and integrated development tools.

When we forego these abstractions and program directly on the microprocessor or microcontroller, we’re working on the bare metal. [Sergey] aptly defines this as programming the microcontroller “using just a compiler and a datasheet, nothing else.” His guide starts at the very foundation by examining the processor’s memory map and registers including locations for memory mapped I/O pins and other peripherals.

The guide walks us through writing up a minimal firmware program from boot vector to blinking an LED connected to an I/O pin. The demonstration continues with setup and use of necessary tools such as the compiler, linker, and flasher. We move on to increasingly advanced topics like timers, interrupts, UART output, debuggers, and even configuring an embedded web server to expose a complete device dashboard.

While initially more time consuming, working close to the metal provides a good deal of additional insight into, and control over, hardware operations.  For even more on the subject, you may like our STM32 Bootcamp series on bare-metal STM32 programming.