MCU Music: Home Multi-zone Arduino Audio

Members of the Humboldt Microcontrollers Group have a more than average interest in microcontrollers (MCUs) and music, e.g. the Humboldt Laser Harp (HLH) and Raspberry Pi music systems.

We've got the proof-of-concept HLH working, but we need to take the next step in expanding the musical capabilities of the HLH. After I talk with Ed, Nick and others in the MCU group about how to most cost effectively improve the music from the harp, I'll write a post about electronic music component options. In the meantime, here's an MCU music topic I read about in an August 2014 Atmel blog post.

Custom PCB fabbed by OSH Park

The Atmel post points to an Instructables titled "The Smartphone Operated House-Wide Audio System" that talks about a system that:

"...solves the seemingly ubiquitous problem of being able to listen to your music from anywhere in your house. Say goodbye to a separate iPod dock in each room! This instructable will show you step-by-step how to build a house wide, multi zone audio system which can be entirely controlled from your Smartphone or computer (really anything with a web browser) from anywhere in your house which you have a Wifi connection...it's also expandable to however many zones you need...this system allows you to use speakers and amps of your choosing and at a fraction of the cost of a Sonos system. In this project we will be making use of an Arduino uno with an ethernet shield and a custom PCB which can be ordered from your favorite PCB manufacturer (I recommend OSH Park). The central component of the PCB is the PT2258 IC. This IC allows for volume control of 6 audio channels and communicates with the Arduino over the I2C bus."

Arduino with Ethernet shield and custom PCB with PT2258 IC

The Princeton Technology datasheet for the PT2258 IC shows the block diagram and pin configuration for this component. Reading over the Tutorialsto.com write-up about the IC will give you a general understanding of the component if you don't already know what it is.

Lepai LP-2020A+ amplifier

This MCU project is more complicated than some projects in other posts I've written, but it will give you good experience in doing activities like ordering a custom PCB (printed circuit board), soldering components on the custom PCB, and hooking up your fabbed and assembled custom PCB with a 6-channel amp and power supply. The Instructables has a pretty good set of photos showing how to solder the components on the PCB, so don't worry about that step if you haven't assembled many, or any, PCBs. The two amplifier options listed in the project write-up both look fun to work with; a Lepai LP-2020A+ for about $20 or a Parts Express AA-AB34181 for about $60.

The Instructables project author describes using the finished audio system this way:

Parts Express AA-AB34181 amplifier

"In order to maintain the idea of being able to control the system from a smartphone, I used a Chromecast with an HDMI audio extractor. This allows us to take the audio the Chromecast outputs and plug it into our PT2258 control board. Thus we can simply cast our favorite Pandora station or music from Google Play Music to the Chromecast and control the volume from our Arduino. Simply plug the Chromecast into a TV and set it up on your home network, then unplug it from the tv and plug it into the HDMI audio extractor. Using a RCA to 3.5mm cable, plug the HDMI audio extractor into the input of the PT2258 board...The system can be controlled by anything which has a web browser and is connected to your home network. All you have to do is type in the IP address of the arduino followed by "/?app" (i.e. 192.168.1.199/?app) and you will be brought to the control app for the system...The greatest limitation of this system is the fact that there is only one audio input for the entire system. That means you have to listen to the same song throughout the entire house."

This system costs about $300 to build, so I won't be putting one together any time soon, but the project gives a good overview of setting up a pretty versatile home audio system from scratch.

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