BOM

• Raspberry Pi 3
• USB microphone
• 2x Audio amplifier
• Speaker
• Button

Wiring

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With the Raspberry Pi as the centerpiece, I went about connecting everything together.  The first step was wiring up the sound.  I took a stereo audio cable plugged into the Raspberry Pi’s audio port and wired each of the left and right channels into its own amplifier.  The power and ground of both amplifiers was sourced from the Raspberry Pi’s 5V and GND pins on the GPIO header.  I then wired the outputs of one of the amplifiers to the speaker.  The outputs of the other amplifier were wired to the LED in the button.  By doing this, the light inside of HAL’s eye would flash in sync with the audio being played.  Aside from that, all that was left to do was plug in the USB microphone and I was done.  One optional addition I might make in the future is wiring up the inputs of the button.  This would provide the possibility to activate Alexa via means other than the wake word.

I originally thought this blog post was going to be a lengthy explanation of how to install the Alexa software (found here) on the Raspberry Pi 3 with all of the caveats, tweaking, and reconfiguration necessary to get the software to install.  Any Linux user who frequently installs software from source knows that the time it takes to get some software to compile and install is exponentially proportional to the complexity of the code and the compile time.  This is not the case here.

It did take roughly an hour to run the automated install script provided in the Alexa repository, but once that had completed everything ran almost perfectly right out of the box.  I’m utterly floored by this, and am incredibly impressed with the Alexa development team on the quality of their software project.  So really, if this is something you’re interested in doing, use their guide to set up everything.  All you really need is a Raspberry Pi 3, a microphone (I used this one), and a speaker (I used one from Adafruit which I’ll discuss in detail in my post on wiring).  The only thing I had to tweak was forcing the audio to be output on the 3.5mm jack using raspi-config and selecting the jack in Advanced Options->Audio.

And without further ado, my working example.

A HAL 9000 replica has been on my “to make” list since Adafruit started stocking their massive, red arcade button.  They even created a tutorial for building a HAL replica!  When the Alexa developers added support for a wake word last month, I knew I had to build it.  Rather than simply playing sound effects with the Pi, I wanted to include Amazon’s new Alexa sample that allows to run the Amazon Echo software on the Raspberry Pi 3.  Always a fan I tempting fate, I thought the HAL replica would be the perfect container for a voice assistant that has access to all of my smart home appliances.  What could go wrong?