Skills

359 Articles

The Linux Throwie: Powering A Linux Server With A 0.3W Solar Panel

November 2, 2018 by 63 Comments

Have you ever had one of those moments, when you’re rummaging through your spare parts heap, and have a rather bizarre project idea that you can’t quite get out of your head? You know, the ones that have no clear use, but simply demand to be born, of glass and steel and silicon?

This time, the stubborn idea in question was sort of like a solar-rechargeable LED throwie, but instead of a blinking light, it has a fully cloud-accessible embedded Linux server in the form of a Raspberry Pi 3 Model B+. Your choice of embedded Linux board should work — I just happen to have a lot of these due to a shipping error.

There were two main challenges here: First, it would have to combine the smallest practical combination of solar panel, power supply, and Li-ion cell that could run the Raspberry Pi. Second, we’ll need to remotely activate and access the Pi regardless of where it is, as well as be able to connect it to WiFi without direct physical access. In this article we’ll be dealing with the first set of problems — stay tuned for the rest.

Continue reading “The Linux Throwie: Powering A Linux Server With A 0.3W Solar Panel” →

The Machinists’ Mantra: Precision, Thy Name Is Rigidity

October 25, 2018 by 40 Comments

“Everything is a spring”. You’ve probably heard that expression before. How deep do you think your appreciation of that particular turn of phrase really is? You know who truly, viscerally groks this? Machinists.

As I’ve blathered on about at length previously, machine tools are all about precision. That’s easy to say, but where does precision really come from? In a word, rigidity. Machine tools do a seemingly magical thing. They remove quantities of steel (or other materials medieval humans would have killed for) with a slightly tougher piece of steel. The way they manage to do this is by applying the cutting tool to the material within a setup that is so rigid that the material has no choice but to yield. Furthermore, this cutting action is extremely precise because the tool moves as little as possible while doing so. It all comes down to rigidity. Let’s look at a basic turning setup.

Continue reading “The Machinists’ Mantra: Precision, Thy Name Is Rigidity” →

Hack My House: Running Raspberry Pi Without An SD Card

October 8, 2018 by 62 Comments

Many of us have experienced the pain that is a Raspberry Pi with a corrupted SD card. I suspect the erase-on-write nature of flash memory is responsible for much of the problem. Regardless of the cause, one solution is to use PXE booting with the Raspberry Pi 3. That’s a fancy way to say we’ll be booting the Raspberry Pi over the network, instead of from an SD card.

What does this have to do with Hacking My House? As I discussed last time, I’m using Raspberry Pi as Infrastructure by building them into the walls of every room in my house. You don’t want to drag out a ladder and screwdriver to swap out a misbehaving SD card, so booting over the network is a really good solution. I know I promised we’d discuss cabling and cameras. Think of this as a parenthetical article — we’ll talk about Ethernet and ZoneMinder next time.

So let’s dive in and see what the Preboot Execution Environment (PXE) is all about and how to use PXE with Raspberry Pi.

Continue reading “Hack My House: Running Raspberry Pi Without An SD Card” →

Laser Noob: Getting Started With The K40 Laser

September 27, 2018 by 77 Comments

Why spend thousands on a laser cutter/engraver when you can spend as little as $350 shipped to your door? Sure it’s not as nice as those fancy domestic machines, but the plucky K40 is the little laser that can. Just head on down to Al’s Laser Emporium and pick one up.  Yes, it sounds like a used car dealership ad, but how far is it from the truth? Read on to find out!

Laser cutting and engraving machines have been around for decades. Much like 3D printers, they were originally impossibly expensive for someone working at home. The closest you could get to a hobbyist laser was Epilog laser, which would still cost somewhere between $10,000 and $20,000 for a small laser system. A few companies made a go with the Epilog and did quite well – notably Adafruit used to offer laptop laser engraving services.

Over the last decade or so things have changed. China got involved, and suddenly there were cheap lasers on the market. Currently, there are several low-cost laser models available in various power levels. The most popular is the smallest – a 40-watt model, dubbed the K40. There are numerous manufacturers and there have been many versions over the years. They all look about the same though: A blue sheet metal box with the laser tube mounted along the back. The cutting compartment is on the left and the electronics are on the right. Earlier versions came with Moshidraw software and a parallel interface.

Continue reading “Laser Noob: Getting Started With The K40 Laser” →

How To Add UART To Your FPGA Projects

September 6, 2018 by 18 Comments

Being able to communicate between a host computer and a project is often a key requirement, and for FPGA projects that is easily done by adding a submodule like a UART. A Universal Asynchronous Receiver-Transmitter is the hardware that facilitates communications with a serial port, so you can send commands from a computer and get messages in return.

Last week I wrote about an example POV project that’s a good example for learn. It was both non-trivial and used the board’s features nicely. But it has the message hard coded into the Verilog which means you need to rebuild the FPGA every time you want to change it. Adding a UART will allow us to update that message.

The good news is the demo is open source, so I forked it on GitHub so you can follow along with my new demo. To illustrate how you can add a UART to this project I made this simple plan:

Continue reading “How To Add UART To Your FPGA Projects” →

Intro To Docker: Why And How To Use Containers On Any System

September 5, 2018 by 72 Comments

If you have your ear even slightly to the ground of the software community, you’ll have heard of Docker. Having recently enjoyed a tremendous rise in popularity, it continues to attract users at a rapid pace, including many global firms whose infrastructure depends on it. Part of Docker’s rise to fame can be attributed to its users becoming instant fans with evangelical tendencies.

But what’s behind the popularity, and how does it work? Let’s go through a conceptual introduction and then explore Docker with a bit of hands-on playing around.

Continue reading “Intro To Docker: Why And How To Use Containers On Any System” →

How To Mash Up BLE, NodeJS, And MQTT To Get Internet Of Things

August 24, 2018 by 10 Comments

We’re living in the world of connected devices. It has never been easier to roll your own and implement the functionality you actually want, rather than live with the lowest common denominator that the manufacture chose.

In a previous article I walked though a small python script to talk to a BLE light and used it to cycle through some colors. Now I want to delve deeper into the world of Internet Connected BLE devices and how to set up a simple Internet-Of-Things light. With this example in hand the sky’s the limit on what you can build and what it will be able to do.

Join me after the break as I demonstrate how to use NodeJS to bridge the digital world with the physical world.

Continue reading “How To Mash Up BLE, NodeJS, And MQTT To Get Internet Of Things” →