Author: Bryan Cockfield

1852 Articles

How Many LEDs Can You Drive?

February 18, 2020 by 35 Comments

Driving more than a handful of LEDs from a microcontroller is often a feat that takes tedious wiring, tricking the processor, or a lot of extra external hardware. Charlieplexing is perhaps the most notorious of these methods, and checks two of those three boxes. This library for the Teensy 4.0 checks all three, but it can also drive a truly staggering 32,000 LEDs at one time.

The TriantaduoWS2811 library is able to drive 32 channels of LEDs from a Teensy 4.0 using only three pins and minimal processor resources. It uses the FlexIO and DMA subsystems of the i.MX RT1062, the particular ARM processor on the Teensy, to drive four external shift registers. Together, the system is able to achieve 30 frames per second on with 1,000 LEDs per channel, for a total of 32,000 LEDs. Whoah.

[Ward] aka [wramsdell] wondered what one would do with all of the horsepower of a Teensy microcontroller when he first saw its specifications, and was able to build this project to take advantage of its features. What’s surprising, though, is that it doesn’t use nearly everything the processor is capable of, so you can do other tasks at the same time as driving that giant LED display.

Hands-Free Oreo Dispenser, Now With Milk

February 9, 2020 by 15 Comments

A while back, [Emiel] aka [The Practical Engineer] created a hands-free Oreo dispenser for his shop. This was a necessary addition to his fleet of handy tools, and allowed him to multitask much more effectively by using a sander, for example, at the same time that he needed to eat a cookie. Of course, this time-saving device was missing one crucial element: milk. [Emiel] is back in this video to show off his milk-dispensing upgrade to his original Oreo dispenser.

A few ideas were considered before [Emiel] decided to build a separate unit for the milk dispenser, so as not to create a gigantic mess any time an Oreo was delivered, and also to maintain some decorum in the shop. He rebuilt the Oreo dispenser with a 3D printer and then also 3D printed the milk dispenser. The chin-activated switch inside the device turns on a small pump which squirts milk into the user’s mouth, presumably after an Oreo has been delivered.

There are a few problems with the build, but most are easily solved by replacing non-food-grade parts with plastic that is more safe for being around consumables. The only other thing we can see here is that it might be a little hard to keep things clean, both inside and out, but most Oreo-related builds like this one have at least some problem with cleanliness that isn’t impossible to keep up with.

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USB Password Keeper Runs On Tiny Chip

February 8, 2020 by 37 Comments

The most important rule of password use, especially when used for online logins, is to avoid reusing passwords. From there, one’s method of keeping track of multiple passwords can vary considerably. While memorization is an option in theory, in practice a lot of people make use of a password manager like Lastpass or KeePass. For those with increased security concerns, though, you may want to implement a USB password keeper like this one based on an ATtiny.

This password keeper, called “snopf”, is a USB device with an ATtiny85 which adds a layer of separation to password keeping that increases security substantially. Passwords are created by the USB device itself using a 128-bit key to generate the passwords, which are physically detached from the computer. Password requests are made by the computer to the USB device, but the user must push a button on the snopf in order to send the password to the computer. It does this by emulating a keyboard, keeping the password information off of the computer’s clipboard.

Of course, snopf isn’t perfectly secure, and the project’s creator [Hajo] goes into detail on the project’s page about some of the potential vulnerabilities. For most use cases, though, none of these are of serious concern. Upgrading your password keeper to a physical device is likely to be a huge security improvement regardless, and one was actually developed on Hackaday a few years ago.

Solving The Mysteries Of Grounding While Improving A Power Supply

February 4, 2020 by 22 Comments

Grounding problems and unwanted noise in electrical systems can often lead to insanity. It can seem like there’s no method to the madness when an electrical “gremlin” caused by one of these things pops its head out. When looking more closely, however, these issues have a way of becoming more obvious. In a recent video, [Fesz Electronics] shows us how to investigate some of these problems by looking at a small desktop power supply, modelling it in LTSpice, and reducing the noise on the power supply’s output.

While everything in this setup is properly grounded, including the power supply and oscilloscope, the way the grounding systems interact can contribute to the high amount of noise. This was discovered by isolating the power supply from earth ground using electrical tape (not recommended as a long-term solution) and seeing that the noise was reduced. However, the ripple increased substantially, so a more permanent fix was needed. For that, the power supply was modelled in LTSpice. This is where a key discovery was made: since all the parts of the power supply aren’t ideal, noise can be introduced from the actual real-life electrical behavior of some of the parts. In this case, it was non-ideal capacitance in the transformer.

According to the model, this power supply could be improved by adding a larger capacitor across the output leads, and also by increasing their inductance. A large capacitor was soldered in the power supply and an iron ferrule was added, which decreased the noise level from 100 mV to around 20. Still not perfect, but a much needed improvement to the simple power supply. If, on the other hand, you want to make sure you eliminate that transformer’s capacitance completely, you can always go with a transformerless power supply. That carries other risks, though.

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Unlocking Hidden Potential In IvyBridge ThinkPads

February 3, 2020 by 37 Comments

Upgrading the BIOS in older computers is a great way to get a few more years of life out of old hardware or improve its performance. ThinkPads are a popular choice around these parts, but often flashing new firmware involves directly programming the chips themselves. Luckily, there’s a new flashing tool for some older Thinkpads that is much simpler.

The ThinkPads involved are the xx30 models with IvyBridge processors built around 2012, and a tool called 1vyrain now allows unlocking the bios without disassembling your computer. This means that there’s support for custom BIOS images such as coreboot, and in certain computers this also allows for overclocking, replacing WLAN hardware, and a number of other customizations. It will also allow you to disable the Intel management engine, which is not something we tire of talking about.

If you have one of these older computers floating around, some new RAM, an SSD, and this update will get you well on your way to a computer that feels brand new at virtually no cost, and the upgrades to the BIOS that you can easily make now only add to that. ThinkPads are a popular choice, especially for their hardware, but you do need to make sure that the software on them is trustworthy too.

Header image: Ashley Pomeroy [CC BY-SA 4.0].

Microcontroller Studies The Blade

February 2, 2020 by 8 Comments

Kendo, a Japanese martial art, is practiced with a special sword. It’s not a particularly sharp sword, though, since the “blade” is essentially a length of bamboo. For this reason, Kendo practitioners must rely on correct form and technique in order to make sure their practice is as effective as possible, and Cornell students [Iman] and [Weichen] have made a Kendo trainer that helps the swordsmen in their art.

The core of the project is a PIC32 microcontroller hooked up to a set of three piezoelectric sensors and a LSM9DS1 inertial module. The three piezoelectric sensors are attached to a helmet and the inertial module to the sword, and the sensors work together to determine both the location of the strike and whether or not it had enough strength to be considered a “good” strike (the rules of Kendo are beyond the scope of this article). The trainer can then calculate all of the information and provide feedback to the user on a small screen.

While martial-arts related builds seem to be relatively rare, we did find a similar project from back in 2011 called the Virtual Sensei which used a then-popular Kinect in order to track movements. This PIC32-based project, though, seems to be a little more thorough by including the strength of the strike in the information the computer uses, and is probably less expensive to boot!

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See-Through Catalytic Converter

February 1, 2020 by 16 Comments

There’s always something to be learned from taking things apart. Sometimes the parts can be used for other things, sometimes they can be repaired or improved upon, but sometimes it’s all in good fun. Especially in this case where extremely high temperatures and combustible gasses are involved. This is from the latest video from [Warped Perception] that lets us see inside of a catalytic converter as its operating.

Catalytic converters are installed on most vehicles (and other internal combustion engines) in order to process unburned hydrocarbons from exhaust gasses with a catalyst. These can get extremely hot, and this high temperature complicated the build somewhat. There were two prototypes constructed for this build and the first was a cross-section of a catalytic converter with a glass window sealed on in order to allow the viewing of the catalyst during the operation of a small engine. It was easy to see the dirty exhaust gasses entering and cleaner gasses leaving, but the window eventually blew off. The second was a complete glass tube which worked much better until the fitting on the back finally failed.

A catalytic converter isn’t something we’d normally get to see the inside of, and this video was worth watching just to see one in operation in real life. You could also learn a thing or two about high-temperature fittings as well if you’re so inclined. It might be a nice pairing with another build we’ve seen which gave us a window into a different type of combustion chamber than ones normally found on combustion engines.

Thanks to [Ryoku] for the tip!

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