Author: John Elliot V

140 Articles

[Piers] explains his code

A Deep Dive Into Using PIO And DMA On The RP2350

November 30, 2025 by No comments

Here’s a fun rabbit hole to run down if you don’t already have the RP2040/RP2350 PIO feather in your cap: how to serve data without CPU intervention using PIO and DMA on the RP2350.

If you don’t know much about the RP2040 or RP2350 here’s the basic run down: the original Raspberry Pi Pico was released in 2021 with the RP2040 at its heart, with the RP2350 making its debut in 2024 with the Pico 2. Both microcontrollers include a feature known as Programmed I/O (PIO), which lets you configure tiny state machines and other facilities (shift registers, scratch registers, FIFO buffers, etc) to process simple I/O logic, freeing up the CPU to do other tasks.

The bottom line is that you can write very simple programs to do very fast and efficient I/O and these programs can run separately to the other code running on your micro. In the video below, [piers] explains how it works and how he’s used it in his One ROM project.

This is the latest installment from [piers rocks] whose One ROM project we’ve been tracking since July this year when we first heard about it. Since then we’ve been watching this project grow up and we were there when it was only implemented on the STM32F4, when it was renamed to One ROM, and when it got its USB stack. Along the way [piers rocks] was on FLOSS Weekly Episode 850: One ROM To Rule Them All too.

Have you seen PIO being put to good use in other projects? Let us know in the comments, or on the tips line!

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The box of the Busch Electronic Digital-Technik 2075

The Busch Electronic Digital-Technik 2075 Digital Lab From The 1970s

November 26, 2025 by 6 Comments

In a recent video, [Jason Jacques] demos the Busch Electronic Digital-Technik 2075 which was released in West Germany in the 1970s.

The Digital-Technik 2075 comes with a few components including a battery holder and 9 V battery, a push button, two 1 K resistors, a red LED, a 100 nF ceramic capacitor, a 100 µF electrolytic capacitor, a quad NAND gate IC, and a counter module which includes an IC and a 7-segment display. The kit also comes with wires, plugs, a breadboard, and a tool for extracting modules.

The Digital-Technik 2075 doesn’t use the spring terminals we see in other project labs of the time, such as the Science Fair kits from Radio Shack, and it doesn’t use modular Denshi blocks, such as we saw from the Gakken EX-150, but rather uses wire in conjunction with yellow plastic plugs. This seems to work well enough.

In the video, after showing us how to do switch debouncing, [Jason] runs us through making a counter with the digital components and then getting the counter to reset after it counts to five. This is done using NAND gates. Before he gets stuck into doing a project he takes a close look at the manual (which is in German) including some of the advertisements for other project labs from Busch which were available at the time. As he doesn’t speak German [Jason] prints out an English translation of the manual before working through it.

We’ve heard from [Jason] at Hackaday in recent history when we saw his Microtronic Phoenix Computer System which referenced the 2090 Microtronic Computer System which was also made by Busch.

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[Usagi Electric] brandishing his raygun

Barcodes, “Lasers”, And Fourier Transforms

November 24, 2025 by 14 Comments

The Bomem DA3 is a type of Fourier transform spectrometer used for measuring various spectral data and [Usagi Electric] has one. On his quest to understand it he runs down a number of rabbit holes, including learning about various barcode formats, doing a teardown of the Telxon LS-201 barcode scanner, and exploring how lasers work. That’s right: lasers!

His reason for looking at the Telxon LS-201 barcode scanner is that it has the same type of helium-neon laser as his Bomem DA3 uses. Since he’s learning about barcode scanners he thinks it’s prudent to learn about barcode formats too, and he has a discussion with our very own Adam Fabio about such things, including the UPC-A standard barcodes.

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Schematic of a voltage divider

Making Actually Useful Schematics In KiCad

November 21, 2025 by 26 Comments

[Andrew Greenberg] has some specific ideas for how open-source hardware hackers could do a better job with their KiCad schematics.

In his work with students at Portland State University, [Andrew] finds his students both reading and creating KiCad schematics, and often these schematics leave a little to be desired.

To help improve the situation he’s compiling a checklist of things to be cognisant of when developing schematics in KiCad, particularly if those schematics are going to be read by others, as is the hope with open-source hardware projects.

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Server racks branded with Internet Archive

Internet Archive Hits One Trillion Web Pages

November 18, 2025 by 14 Comments

In case you didn’t hear — on October 22, 2025, the Internet Archive, who host the Wayback Machine at archive.org, celebrated a milestone: one trillion web pages archived, for posterity.

Founded in 1996 by Brewster Kahle the organization and its facilities grew through the late nineties; in 2001 access to their archive was greatly improved by the introduction of the Wayback Machine. From their own website on Oct 21 2009 they explained their mission and purpose:

Most societies place importance on preserving artifacts of their culture and heritage. Without such artifacts, civilization has no memory and no mechanism to learn from its successes and failures. Our culture now produces more and more artifacts in digital form. The Archive’s mission is to help preserve those artifacts and create an Internet library for researchers, historians, and scholars.

We were curious about the Internet Archive technology. Storing a copy (in fact two copies!) of the internet is no mean feat, so we did some digging to find out how it’s done. The best information available is in this article from 2016: 20,000 Hard Drives on a Mission. They keep two copies of every “item”, which are stored in Linux directories. In 2016 they had over 30 petabytes of content and were ingesting at a rate of 13 to 15 terabytes per day, web, and television being the most voluminous.

In 2016 they had around 20,000 individual disk drives, each housed in specialized computers called “datanodes”. The datanodes have 36 data drives plus two operating system drives per machine. Datanodes are organized into racks of 10 machines, having 360 data drives per rack. These racks are interconnected via high-speed Ethernet to form a storage cluster.

Even though content storage tripled over 2012 to 2016, the count of disk drives stayed about the same; this is because of disk drive technology improvements. Datanodes that were once populated with 36 individual 2 terabyte drives are today filled with 8 terabyte drives, moving single node capacity from 72 terabytes (64.8 T formatted) to 288 terabytes (259.2 T formatted) in the same physical space. The evolution of disk density did not happen in a single step, so there are populations of 2, 3, 4, and 8 T drives in the storage clusters.

We will leave you with the visual styling of Hackaday Beta in 2004, and what an early google.com or amazon.com looked like back in the day. Super big shout out to the Internet Archive, thanks for providing such an invaluable service to our community, and congratulations on this excellent achievement.

Photo of [DENKI OTAKU] with his test circuit and oscilloscope

Exploring The Performance Gains Of Four-Pin MOSFETs

November 17, 2025 by 9 Comments

Over on YouTube [DENKI OTAKU] runs us through how a 4-pin MOSFET works and what the extra Kelvin source pin does.

A typical MOSFET might come in a 3-pin TO-247 package, but there are 4-pin variants which include an extra pin for the Kelvin source, also known as source sense. These 4-pin packages are known as TO-247-4. The fourth pin provides an additional source for gate current return which can in turn lessen the effect of parasitic inductance on the gate-source when switching current, particularly at high speed.

In the video [DENKI OTAKU] uses his custom made testing board to investigate the performance characteristics of some 4-pin TO-247-4 MOSFETs versus their 3-pin TO-247 equivalents. Spoiler alert: the TO-247-4 MOSFETs have better performance characteristics. The video takes a close look at the results on the oscilloscope. The downside is that as the switching speed increases the ringing in the Vds waveform increases, too. If you’re switching to a 4-pin MOSFET from a 3-pin MOSFET in your design you will need to be aware of this Vds overshoot and make accommodations for it.

If you’d like to go deeper with MOSFET technology check out Introduction To MOSFET Switching Losses and MOSFETs — The Hidden Gate.

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[Usagi Electric] and his home brew computer

TMS9900-based Home Brew Computer

November 17, 2025 by 3 Comments

[Usagi Electric] is known for minicomputers, but in a recent video, he shows off his TMS9900-based homebrew computer. The TMS9900 CPU was an early 16-bit CPU famously used in the old TI-99/4A computer, but as the video points out, it wasn’t put to particularly good use in the TI-99/4A because its RAM was hidden behind an inefficient interface and it didn’t leverage its 16-bit address space.

The plan is for this computer to have 2K words of ROM, 6K words of RAM, and three serial lines: one for the console terminal, another for a second user console terminal, and the third for access to a tape drive.

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