33 Snowflakes

Here’s another use for the Arduino Ethernet — A networked 4-zone speaker selector. It lets me output audio from my receiver across the house using Android!

90-Second Demo Video! (Youtube)

I ordered the OSD ISS4 High Power 4-Zone Speaker Selector with Impedance Protection (Black) which provides 4 big buttons to add 4 speaker zones to your powered second zone (or first zone, even). The watts delivered to a speaker varies based on how many speakers you have turned on, because there are resistors that get turned on/off to keep your receiver/amplifier from frying (impedance protection).

I hooked it up to the Arduino using this Arduino-compatible relay: SainSmart 8-Channel 5V Relay Module for Arduino. For four zones, it turns out you need 8 relays (4 left speakers & 4 right speakers).

To each of the four contacts below each of the four switches, you’ll need to solder a cable. They’re using one switch to connect both the left and right speakers, so we’re going to have 16 solder points.

First zone is done:

Here it is hooked up:

And the whole system:

(The breadboard has a 315MHz transmitter, see my last blog post to find out why)

I added the code to my Arduino webserver, which will handle requests at /speakerStatus to see which are active, and /speaker?zone=&state=<0/1> to turn a zone on/off.

Check that code out on Bitbucket here!

I’ve also got a barebones Android app that will request those URLs for you. Code for that is also in the above repo. In addition to the basic functionality – querying status and updating the zones, a long-press on a button will allow you to rename any zone.

Now I just need a web-enabled receiver for my Pandora/Spotify playing. This is the one on my wishlist: Onkyo TX-NR515 Network A/V Receiver, and of course it comes with an Android/iPhone app for remote control!

Here’s a fun new Arduino project I’m tackling – controlling wireless outlets from the internet!

At $6 per outlet, it’s a steal. I got lucky and found all 4 channels of these wireless/RF outlets at Big Lots:

Similar outlets on Amazon

Compare that pricing to Belkin’s WeMo ($50 per outlet).

3 days of crunch time over the holidays, and I’ve got the switches working from the Web. I’m going to start working on an Android front-end, and hope to finish by the time I close on my new home.

I made a quick demo video over here on Youtube.

And all the code is on Bitbucket.

This is what the circuit looks like… very simple, just hook up the 4 pins of the transmitter to the correct place.

I based the code on a cool outlet project that ze Germans have done, but in Europe the RF protocols and outlets are a bit different. There was also a reference from Instructables, but those timings didn’t match my outlets. If you don’t have luck with my code as-is, modify the pulse length timings to match what is found here. There may be more variants that look the same.

I managed to use my Arduino as a logic analyzer to figure out what exactly wasn’t working, and that was probably the most fun part of the project. I soldered leads onto the stock wireless remote to spy on the signal that was being transmitted, and saw the digital signal graph on my TV screen. Amazing! As a programmer, I forget sometimes that there is electricity flowing through everything and changing direction every few nanoseconds.

This Arduino logic analyzer is a great project, and saved me big time here. It has 500 kHz max resolution, but since there is only 1kb of RAM, you’re limited to 1024 samples. That resolution was actually so good, that the first few times I thought it wasn’t working… I was zoomed in too far and didn’t see any transitions. As soon as I zoomed out to 1 kHz, I saw everything! And 20 kHz was finally the sweet spot to measure the timings accurately.

This is how I instrumented the remote control for use with the logic analyzer. I soldered many jumpers onto the circuit — only 2 carried the signal I wanted. The orange wire, and the right-most white wire both had the correct waveform — though the white one was inverted. I also provided power from the Arduino, since the remote had a 12V battery, some traces might have been carrying too much juice for the Arduino!

Next stop is to provide a GUI — either HTML 5 or a native app. I will likely go native, so I can hook into other Android automation apps down the line, using one APK as a launcher for the others — one app to rule them all.

Feel free to provide critique or suggestions!