HOWTO

Creating a sensor or peripheral with an SPI (slave) interface
Creating a sensor or peripheral with an SPI (slave) interface

Designed to interact with a 16-bit I/O expander, the firmware was ready for testing.  Though I was still waiting on parts, I wanted to make sure it would all work as expected.  What’s an impatient developer to do?  Create his own SPI slave to replace the missing part, of course! If you’ve gotten anywhere beyond…

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Real world Kicad project postmortem and more tips
Real world Kicad project postmortem and more tips

As a follow-up to my intro/tutorial, I’ll go over a few more lessons learned using Kicad including some tips that should be of help to anyone embarking on a similar journey. The power module project was selected for a first adventure using Kicad as it was relatively small while being non-trivial.  The circuit holds around…

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Kicad: Techniques, Tips and Work-arounds
Kicad: Techniques, Tips and Work-arounds

Kicad is an cross-platform, open source, electronics design suite.  I’d toyed with it in the past, but had never made it to actually designing real projects with it until recently.  Here, I’ll go over my experience and initial impressions, and provide a few pointers and resources for anyone curious about trying it out.  We’ll tour…

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Transmitting mounds of data in realtime over Bluetooth Low Energy
Transmitting mounds of data in realtime over Bluetooth Low Energy

My client needed to receive a relatively large amount of data on a mobile device, from an embedded system, and process it in near-realtime.   The simplest method for communication with a whole host of mobile devices is to go over bluetooth low energy, but this protocol’s main concern is more about power conservation than throughput. …

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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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