HOWTO

Turning complex waveforms into usable values–VRMS, Power, Torque… how to do it and why it works

After this tutorial, you’ll know “in your bones” how to deal with the weirder stuff, when it comes to time-dependent values. It’s easy to find formulas to plug into to for simple cases, like a steady DC voltage or nice sine waves with known peak values but what happens when things aren’t so straightforward?  Say…

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Finding a messy signal’s period and frequency, the easy way
Finding a messy signal’s period and frequency, the easy way

I’ve recently had to determining the frequency of some arbitrary repeating signal, from a stream of sampled values. In a simple universe, you could just wait for a specific value to come in–say the peak value–or monitor for the zero crossing or somesuch. However, the particulars in this case included the fact that, in addition…

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Getting the Hantek DSO-2090 working with Linux
Getting the Hantek DSO-2090 working with Linux

Received a Hantek DSO-2090 USB oscilloscope today and put it through a few paces.  Here are the results and my impressions from using the device a bit, as well as a few tips for working with it under Linux. The first thing to note is that, in terms of DSOs, this thing is dirt cheap…

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Announcing NanoKeys: turning a BLE Nano into an HID Keyboard, the easy way
Announcing NanoKeys: turning a BLE Nano into an HID Keyboard, the easy way

I’m finishing up the docs for NanoKeys, a small BLE Nano (and probably any mbed BLE API supported devices) library that gives you an easy way to create a bluetooth low energy keyboard that you can pair with using any mobile device. The project page, code and documentation will be up shortly (in the projects…

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RedBear Duo: Intro and QuickStart/HOWTO
RedBear Duo: Intro and QuickStart/HOWTO

Just got my hands on RedBear Lab‘s Duo—what promises to be a great little BLE/WiFi combo—and got some preliminary testing done.  By the end of the seven straightforward steps detailed here, you’ll know all the basics about the Duo and have your own “Arduino” code running on the device, too.  Other than my own ramblings,…

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Midnight hack: going from SMT to breadboard in a bind

So it’s the middle of the night and I find myself in a jam… hm, a lot of my stories seem to start that way.  Anyhow, it’s the middle of the night and I’m badly stuck: I need to talk with a two-wire chip I have on a breakout, but the I²C communication lines need…

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Squeezing the most out of Raphaël JS for SVG generation

A few hints about squeezing maximum performance out of Raphaël. When you want to generate dynamic SVG images using Javascript, either on a website or within a Cordova-type project on mobile devices, the Raphaël library is pretty sweet.  Raphaël has a nice, clean, API and lets you do pretty much anything graphics-related and it sticks…

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The Handicraft Router
The Handicraft Router

This is a quick post to share a technique I recently invented (or, more likely, re-invented) that can be of great help when you’re trying to layout a circuit but are overloaded by possibilities: the handicraft router. In this specific case, I was trying to get the outputs from a bunch of digital potentiometers to…

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Rectifier/Voltage Regulator module: post-mortem
Rectifier/Voltage Regulator module: post-mortem

Needing a modular power supply that could handle a few amps and both AC and DC input, I recently designed a circuit to perform the task.  Here I’ll go over the main points and a few lessons learned.

Using the on-board Real-Time Clock
Using the on-board Real-Time Clock

So you’re programming for a platform with a built-in RTC… cool.  Now what? Most (all?) XMEGA‘s have an on-board real-time clock, some can even be backed-up by a distinct battery (like the xmega256a3bu, shown below) which can be a real time saver (oh, the pun-anity!). The question then becomes how to best use it. I’ve…

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