Audio on the go

I’ll save you the long back story, but I recently came across a pretty amazing module, the USR-S12.

usrs12

This module seems to be built for integration in other devices, and has an impressive list of features.  The key ones (to me) are:

  • WiFi base station or bridge
  • Airplay

This website has a pretty good breakout of what the interface looks like.

I ordered mine directly from china, for about $35 – but it took about 2 weeks to arrive.  Sparkfun also carries them with a break-out board (including rj45 ethernet) but they want a bit of coin for it.

With module in hand I set about wiring it into my car.  My goal was to stream audio from my iPhone as my car didn’t support the proper bluetooth codecs to play music.  With airplay i could stream podcasts and pandora with a higher sound quality than bluetooth would give me anyways.

My Audi has an interesting interface (AMI) which supports different cables for iphone aux etc.  The ipod cable was interesting to me as it supported analog left/right, data (not used for this application) and power.  I was fortunate to find a wiring diagram for the audi connector on a blog (thanks w.ashcroft!).

audioConnector

The only other sticky-wicket on the Audi part is that there is a small resistor inside the connector housing that tells the car if you have the ipod or the aux cord connected.  I wanted it to think the aux cord was connected so it wouldn’t try to talk via the data lines.  There is a 18.7k resistor in the iPOD cable, and i had to swap that out for a 1k to emulate the AUX cable.

After a quick snip-snip with the wire-cutter the 30-pin ipod connector was removed and I was able to identify which wires were which with a the help of the multi-meter (diode test for the win!).  Soldered power, ground and analog to the USR-S12 and was pretty much ready to go.

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Plugged it in and thankfully everything worked as expected.  Iphone joined the new WiFi hotspot in my glove compartment, and airplay sounded awesome!  I made a few small changes through the web interface (10.10.10.254), changing the network/ssid name.  This also changed the name of the airplay host.

Final change is to edit the network properties on the wireless network on your iPhone.  When joined to this hotspot you want to set a static IP (such as 10.10.10.200) and NO default gateway.  This way your phone will still use the cellular network to get to the internet instead of trying to use the hotspot.  This is critical if you want to stream content like Pandora.

Boo

Whipped up a yard sign for this Halloween.  My wife picked up some really neat orange bulb strings with over sized glass bulbs – no LED’s here!  Scaled up some letters to be about 2’x3′ and layed out a hole pattern so each letter used an entire string.  The holes had to be slightly recessed so the bulbs could screw into the sockets fully.

Painted them up with some exterior paint.  They look nice next to the yard ghosts I got years back from the father-in-law!

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Here are the .dxf files.

New gear begets new gear

It was bound to happen.  I finally got tired of finding the appropriately-sized wall warts to power my workbench projects.  It was time for a new power supply.  I picked up a reasonably priced 30v 5a Korad KD3005D, which seemed to have the small number of features I needed.

Upon its arrival, and after the unpacking excitement waned, I noticed a small problem.  The voltage being produced was way off from the displayed amount.  This was troubling, and an email to the manufacturer brought about a new control board which I swapped out.  Bummer is, the same problem persisted.

Dumb cheap-ass supplies right?  My concern for the second service inquiry is them doubting my technical prowess, so i ordered a second multi-meter.  I wanted to be able to have two meters showing the output, which wouldn’t match the power supply.  So i got a TekPower TP4000ZC ordered (serial output!) off Amazon (thanks prime!).

Wired the new meter up with my old meter (acquired in 1993) and low-and-behold.  Problem on my end.

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My trusty old meter turns out to be not so trusty.  Sorry, Korad – sorry I ever doubted you.  Threw the old meter in the trash and picked up a second TekPower.  Nice to have two.