We received belated word this week of the passage of Ward Christensen, who died unexpectedly back in October at the age of 78. If the name doesn’t ring a bell, that’s understandable, because the man behind the first computer BBS wasn’t much for the spotlight. Along with Randy Suess and in response to the Blizzard of ’78, which kept their Chicago computer club from meeting in person, Christensen created an electronic version of a community corkboard. Suess worked on the hardware while Christensen provided the software, leveraging his XMODEM file-sharing protocol. They dubbed their creation a “bulletin board system” and when the idea caught on, they happily shared their work so that other enthusiasts could build their own systems.
[My Ham Radio Journey] wanted to see if a “common person” (in his words) could build an effective vertical ham radio antenna. If you look at the video below, the answer is apparently yes.
He started with a 24-foot fishing rod and a roll of 22 gauge wire. The height of the antenna wire is just over 20 feet long and he has several ground radials, as you might expect for a vertical antenna.
Last week I completed the SAO flower badge redrawing task, making a complete KiCad project. Most of the SAO petals are already released as KiCad projects, except for the Petal Matrix. The design features 56 LEDs arranged in eight spiral arms radiating from the center. What it does not feature are straight lines, right angles, nor parts placed on a regular grid.
Importing into KiCad
Circuit Notes for LEDs, Thanks to [spereinabox]I followed the same procedures as the main flower badge with no major hiccups. This design didn’t have any released schematics, but backing out the circuits was straightforward. It also helped that user [sphereinabox] over on the Hackaday Discord server had rung out the LED matrix connections and gave me his notes.
Grep Those Positons
I first wanted to only read the data from the LEDs for analysis, and I didn’t need the full Kicad + Python scripting for that. Using grep on the PCB file, you get a text file that can be easily parsed to get the numbers. I confirmed that the LED placements were truly as irregular as they looked.
My biggest worry was how obtain and re-apply the positions and angles of the LEDs, given the irregular layout of the spiral arms. Just like the random angles of six SAO connector on the badge board, [Voja] doesn’t disappoint on this board, either. I fired up Python and used Matplotlib to get a visual perspective of the randomness of the placements, as one does. Due to the overall shape of the arms, there is a general trend to the numbers. But no obvious equation is discernable.
A couple of weeks back, we covered an interesting method for prototyping PCBs using a modified CNC mill to 3D print solder onto a blank FR4 substrate. The video showing this process generated a lot of interest and no fewer than 20 tips to the Hackaday tips line, which continued to come in dribs and drabs this week. In a world where low-cost, fast-turn PCB fabs exist, the amount of effort that went into this method makes little sense, and readers certainly made that known in the comments section. Given that the blokes who pulled this off are gearheads with no hobby electronics background, it kind of made their approach a little more understandable, but it still left a ton of practical questions about how they pulled it off. And now a new video from the aptly named Bad Obsession Motorsports attempts to explain what went on behind the scenes.
We’ll be honest. Measuring Forth words per second doesn’t seem like a great benchmark since a Forth word could be very simple or quite complex. But we think the real meaning is “up to 400 million words per second.” There was a time when that level of performance would take a huge computer. These days, a simple board that costs a few bucks can do the trick, according to [Peter Forth] in an online presentation.
The key is the use of the Milk V Duo and some similar boards. Some of these look similar to a Raspberry Pi Pico. However, this chip on board has two RISC V cores, an ARM core, and an 8051. There’s also an accelerator coprocessor for vector operations like AI or video applications.
This week, Jonathan Bennett and David Ruggles chat with Frank Delporte about Pi4J, the friendly Java libraries for the Raspberry Pi, that expose GPIO, SPI, I2C and other IO interfaces. Why would anyone want to use Java for the Pi? And what’s changed since the project started? Listen to find out!
The best part about real-time OS (RTOS) availability in 2024 is that we developers are positively spoiled for choice, but as a corollary this also makes it a complete pain to determine what the optimal choice for a project is. Beyond simply opting for a safe choice like FreeRTOS for an MCU project and figuring out any implications later during the development process, it can pay off massively to invest some time up-front matching the project requirements with the features offered by these various RTOSes. A few years ago I wrote a primer on the various levels of ‘real-time’ and whether you may even just want to forego an RTOS at all and use a simple Big Loop™ & interrupt-based design.
With such design parameters in mind, we can then look more clearly at the available RTOS options available today, which is the focus of this article. Obviously it won’t be an exhaustive comparison, and especially projects like FreeRTOS have seen themselves customized to various degrees by manufacturers like ST Microelectronics and Espressif, among others. This also brings to the forefront less pleasant considerations, such as expected support levels, as illustrated by e.g. Microsoft’s Azure RTOS (formerly ThreadX) recently getting moved to the Eclipse Foundation as the Eclipse ThreadX open source project. On one hand this could make it a solid open-source licensed RTOS, or it could have been open sourced because Microsoft has moved on to something else and cleared out its cupboard.
Thus without further ado, let’s have a look at RTOSes in 2024 and which ones are worth considering, in my opinion.
