LED spectroscopy

I’m working on a project that will include using LEDs as light sensors, and one of the first tasks is to learn a bit more about the wavelengths of light that are emitted by an array of LEDs. Since I’ve recently created a Mathematica interface to an Ocean Optics spectrometer (on a Raspberry Pi, naturally), the first task was pretty straightforward.

Emission spectra of several LEDs. rgb(b,g,r) are in a common cathode RGB led while the others are varieties from Adafruit.
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More Particle madness

The graphics in this post will no longer work now that I have started a new project with this particle.

Now that I’ve mastered (!) publishing sensor readings from a Particle device and visualizing them with ThingSpeak, it’s time to step up my game a little bit. I have an old BMP180 temperature and pressure sensor that I thought was toast. I’m glad I didn’t throw it out because it seems to be working well.

A static view of temperature and pressure data from a BMP180 sensor connected to a Particle Xenon.

I was interested in this sensor because it reports two values. If I want to send both values to ThingSpeak using the Particle tutorial, I would have to set up two webhooks (and possibly two channels). That seems like a lot of work. I sought an alternative. The particle community has several discussions (such as this one) that show how to do it.

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House temperature monitor

With surprisingly few problems, I have been able to set up a mesh network with a node that is monitoring the temperature of my house. AND I figured out a way to show it dynamically on a web page:

Read on to see the workflow

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