Raspberry Pi Pico ADC Characterized

March 15, 2021 by Al Williams 21 Comments

[Markomo] didn’t find much useful information about the Raspberry Pi PIco’s analog to digital converter, so he decided to do some tests to characterize it. Lucky for us, he documented the findings and shared them. The results are in a series of blog posts that cover power supply noise, input-referred noise, signal to noise ratio, and distortions.

There are some surprising results. For example, the Pico’s low noise regulator mode appears to produce more noise than having it set for normal operation. There also appears to be a large spike in nonlinearity around certain measurements.

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Guitar Effects With No (Unwanted) Delay

March 15, 2021 by Bryan Cockfield 23 Comments

MIDI has been a great tool for musicians and artists since its invention in the 1980s. It allows a standard way to interface musical instruments to computers for easy recording, editing, and production of music. It does have a few weaknesses though, namely that without some specialized equipment the latency of the signals through the various connected devices can easily get too high to be useful in live performances. It’s not an impossible problem to surmount with the right equipment, as illustrated by [Philip Karlsson Gisslow].

The low-latency MIDI interface that he created is built around a Raspberry Pi Pico. It runs a custom library created by [Philip] called MiGiC which specifically built as a MIDI to Guitar interface. The entire setup consists of a preamp to boost the guitar’s signal up to 3.3V where it is then fed to the Pi. This is where the MIDI sampling is done. From there it sends the information to a PC which is able to play the sound back quickly with no noticeable delay.

[Philip] also had to do a lot of extra work to port the software to the Pi which lacks a lot of the features of its original intended hardware on a Mac or Windows machine, and the results are impressive, especially at the end of the video where he uses the interface to play a drum machine via his guitar. And, while MIDI is certainly a powerful application for a guitarist, we have also seen the Pi put to other uses in this musical realm as well.

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Overall view of Alta's Projects cyberdeck

Cyberdeck Running On Apple Silicon, Though An A12 Not An M1

March 10, 2021 by Michael Shaub 15 Comments

[Alta’s Projects] built a two-in-one cyberdeck that not only contains the requisite Raspberry Pi (a zero in this case) but also eschews a dumb LCD and uses an iPad mini 5 for a display.

We need to address the donor case right away. Some likely see this as heresy, and while we love to see vintage equipment lovingly restored, upcycling warms our hearts and keeps mass-produced plastic out of landfills too. The 1991 AST 386SX/20 notebook in question went for $45 on an online auction and likely was never destined for a computer museum.

Why is Cupertino’s iOS anywhere near a cyberdeck? If a touch screen is better than an LCD panel, a tablet with a full OS behind it must be even better. You might even see this as the natural outgrowth of tablet cases first gaining keyboards and then trackpads. We weren’t aware that either was possible without jailbreaking, but [Alta’s Projects] simply used a lighting-to-USB dongle and a mini USB hub to connect the custom split keyboard to the iPad and splurged on an Apple Magic Trackpad for seamless and wireless multi-touch input.

Alta's Projects Cyberdeck Internal USB Wiring — Internal USB Wiring, Charging Circuit, and Pi Zero

The video build (after the break) is light on details, but a quick fun watch with a parts list in the description. It has a charming casual feel that mirrors the refreshingly improvisational approach that [Altair’s Projects] takes to the build. We appreciate the nod to this cyberdeck from [Tinfoil_Haberdashery] who’s split keyboard and offset display immediately sprang to mind for us too. The references to an imagined “dystopian future” excuse the rough finish of some of the Dremel cuts and epoxy assembly. That said, apocalypse or not, the magnets mounted at both ends of the linear slide certainly are a nice touch.

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Laser Zap That Mosquito

March 8, 2021 by Al Williams 98 Comments

When we first heard of [Ildar Rakhmatulin’s] plan to use OpenCV on a Raspberry Pi to detect mosquitos and then zap them with a 1 watt laser, we thought it was sort of humorous. However, the paper points out that 700,000 people die each year from mosquito bites — we didn’t verify that, but according to the article that’s twice the number of people murdered each year. So the little pests are pretty effective assassins.

It looks as though the machine has been built, at least in a test configuration. A galvanometer aims the death ray using mirrors, and with the low power and lossy mirrors the mosquitos can only be a small distance from the machine — about a foot.

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Can Plants Bend Light To Their Self-Preserving Will?

March 4, 2021 by Kristina Panos 34 Comments

It does sound a bit silly — the idea that given enough time, a plant could influence the order of hardware-generated random numbers in order to get enough light to survive. But not so silly that [DeckerM] couldn’t wait to try it out after seeing a short clip about an unpublished study done at Princeton’s Engineering Anomalies Research (PEAR) lab that came to this very conclusion. The actual verbatim conclusion from the clip: “It’s as though life itself – even life or consciousness in something as simple as a house plant, bends probability in the physical world in the direction of what it needs, in the direction of its growth and evolution.”

The idea is this: a plant is made to suffer by languishing in the corner of a windowless room. The room has exactly one light in the middle of the ceiling — a repositionable spotlight of sorts that can only shine into any of the four corners and is controlled by a random number generator. A set of dividers ensure that none of the light leaks out of the quadrant and into any of the others.

[DeckerM]’s recreation of this experiment is much more practical. It’s essentially a little plywood cabinet with four open partitions and a ceiling. Each quadrant has a grow light strip planted in the corner, and all the wires are run through the top, where each has been stripped of its pesky power-governing controller and rewired to go straight into a smart plug. [DeckerM] is using a hardware RNG hosted on a Raspberry Pi, which is running a Python script that takes numbers from the RNG that corresponds to one of the quadrants, and then lights that quadrant.

And the results? They don’t really support the PEAR study’s bold conclusion unless viewed in small sample sizes, but [DeckerM] isn’t giving up that easily. Since the paper is unpublished, there are a lot of unanswered questions and juicy variables to play with, like the type, number, and age of the plants used. We’re excited to see if [DeckerM] can shed some light on plant psychokinesis.

Interested in portable plant propagation? A sunny location is usually ideal, but this all-in-one solution can take care of the rest.

3D-Printed Macro Pad Ditches The PCB With Slick Wiring Guides

March 2, 2021 by Donald Papp 15 Comments

Reddit user [duzitbetter] showed off their design for a 3D-printed programmable macro keyboard that offers a different take on what can be thought of as a sort of 3D-printed PCB. The design is called the Bloko 9 and uses the Raspberry Pi PICO and some Cherry MX-style switches, which are popular in DIY keyboards.

The enclosure and keycaps are all 3D printed, and what’s interesting is the way that the enclosure both holds the components in place as well as providing a kind of wire guide for all the electrical connections. The result is such that bare copper wire can be routed and soldered between leads in a layout that closely resembles the way a PCB would be routed. The pictures say it all, so take a look.

Bloko 9 is available as a paid model, and while going PCB-free thanks to 3D printing is a technique others have played with, it is very well demonstrated here and shows there is still plenty of room to innovate on the concept. DIY keyboard and macro pad design is also fertile ground for hackers; we have even seen that it’s possible to 3D print one right down to the switches themselves.

Useful Build Tips For Making LED Panel Frames

February 23, 2021 by Donald Papp 9 Comments

[NotLikeALeafOnTheWind] has created many LED-based display projects, and shares his method for making attractive LED panel frames and mounts. At first glance it may look as though slapping a rectangle of aluminum extrusion around a display is all it takes, there is also the mounting and management of wiring, power supply, and possibly a Raspberry Pi to deal with. The process of building an attractive frame also has a few hidden gotchas that can be avoided with a bit of careful planning.

Magnetic feet on the LED panels makes mounting much easier and more flexible.

Here is one tip that will resonate with some readers: don’t rely on specified dimensions of parts; measure the actual parts yourself. There can be small differences between what a data sheet says to expect, and the dimensions of the actual part in one’s hands. It may not be much, but it can be the difference between an ideal fit, and something that looks like a bit of a hack job.

[NotLikeALeafOnTheWind] provides some basic frame layouts, and suggests using two- or three-channel extrusions to provide a flat bezel around the display edge if desired. Mounting the LED panel itself is done with magnetic feet and providing a length of steel bar to which the display can attach. This can provide a flush mount while avoiding the whole issue of screw-mounting the display panels themselves, or sliding them into channels. For mounting all the other hardware, a piece of DIN rail and some 3D-printed parts takes care of that.

The result looks slick and sturdy, and some of the tips are sure to be useful even if the whole process isn’t applied. We like the way the basic design scales and is flexible about the thickness and size of the LED panels themselves, making it a promising way to accommodate perfectly functional oddball panels that end up in the trash.