I wanted a solution for getting digital music from my iPad to my stereo and/or speakers. The iPad doesn’t have a toslink or mini-toslink jack which is a bit of a shame, only offering an analog output (on the other hand, do you really want your iPad tethered to a stereo? no). So the solution is to go wireless and get the music out digitally via itunes.

I didn’t have a decent receiver (curse you, Onkyo, and your buggy TX-NR708). Thus, I decided I’d throw my own amplifier together from a few custom (and not-so-custom components). The design goals:

• Must get music from iPad to Amp digitally
• Remote power on/off from computer (i.e. via IP)
• Remote volume from computer
• Visualization (VU meters)
• Low power in standby and operational mode

So let’s take a look at what we got:

and, a view with some captions describing the components:

So, let’s describe the parts:

IN-13 driver boards. These came from Marc BAREILLE at http://m.bareille.free.fr/vu-in13/vumeter_in13.htm. Marc supplies the circuit boards, you supply all the components. The IN-13s themselves came from eBay, from some place in Russia or Ukraine. These board work pretty good and have the high voltage power supply integrated with them.

DC-DC Converter. Right above the IN-13 driver boards is a DC-DC converter. The op-amps on the boards needed +/0 15v to operate, and it was most convenient for me to use the converter to convert over the 24V supply that’s used for the amplifier.

MiniDSP Stack. This includes MiniDigi, MiniDSP, and MiniAMP. These boards come from minidsp.com. It’s a great little digital amplifier, accepting 2x toslink and 2x coaxial inputs. I’m only using 1 toslink at the moment, but future plans (and those unused buttons on the front) may go toward more inputs and a prop-based switching mechanism.

MotorPot. Regular potentiometers aren’t very interesting. Alps makes some nice motorpots, which are pots with motors attached. This one is a 2 channel linear pot. One channel goes to the MiniDSP to control volume. The the other channel is used as feedback to the microcontroller, so that we can see the motorpot to a known position (motorpot presets!)

24V Power Supply. I went with a small commercial switching supply. The idea was to keep power usage low and size compact. It supplies power for the DC-DC converter (IN-13s) and the MiniDSP stack. The 24V supply is switched via a relay controlled by the microcontroller. Power for the Microcontroller is supplied by a separate 5V switching supply, hidden below the Microcontroller board.

Propeller Microcontroller. This is one of my standard “clock” boards from the clock I never made, repurposed to yet another use. It features on-board ethernet via an ENC28J160 chip. The prop then provides built-in web server support allowing amplifier to be turned on/off and volume set remotely. A LTC1298 ADC is used for reading the position of the motorpot, and a L293D H-Bridge is used to operate the motor. Although the motor says it requires 5.5V for stable operation, it seems to operate pretty well from the 5V passed through the L293D (which drops it two diodes worth, to about 3.5V at the motor).

Code:

I’ll probably do more of a write-up of the code when I get some more spare time. The TCP Stack is PropTCP by Harrison Pham, with a bit of customization (it floats around from project to project, getting a bit more modified as time goes by). The PWM code for running the H-Bridge came from the Propeller Book, in the dancebot (Hanno) section. I wrote a custom controller to operate the motor to seek to specific places with feedback; it’d probably be better replaced with a PID controller.

Apple Airport Express. The Airport Express is the digital music receiver. It receives music from the iPad via AirPlay, converts it to toslink digital output, where it feeds into the MiniDSP stack. There just wasn’t a good way to get the music over ethernet without going with a commercial solution. Fortunately, the AE is small and easily hidden in the case.

Here’s a picture of the web page. It’s rather simple at the moment:

One goal was low power utilization. A kill-a-watt measured power-on at 15.7 watts and standby at 5.4 watts respectively. The lion share of the standby power is probably the airport express. I could eliminate that by adding another relay to switch the AE on and off. Problem is the AE has a significant boot time, and I don’t want to be waiting a minute or two every time I turn on my amplifier before the iPad can connect to it. Un-powering the AE also breaks the AirPlay connection requiring it to be re-established. Better to just leave it on and be done with it.

In addition to the Ipad, I can also listen to arbitrary sources via airfoil:

The above picture shows me connected via VNC to my Linux Server in the other room. It’s running VMWare and a Virtual Machine that’s running Windows XP SP2. On this VM is airfoil and XMicroplayer. XMicroplayer is one of my own programs (http://www.sb-software.com/xmplayer) that allows you to stream Sirius and XM. This gives me a great way to stream Sirius Internet Radio onto the amp. XMicroplayer is much more stable than the crappy Sirius iPad App, or I’d probably use the iPad for the task. Best of all, it’s all using spare cycles on hardware (my Linux VM server) that is already running for other purposes.

Future Plans -

• Input switching. There’s two coaxial digital and one toslink remaining on the miniDigi. I’d like to rig the prop to switch the miniDigi between inputs. Shouldn’t be too hard. Three buttons on the front are unused and could be used to switch sources (three buttons, four sources? I’ll have to get inventive…)
• Auto-on. The AE only outputs toslink optical when it’s receiving a signal. It should be possible to split off the toslink to a photodetector and allow the prop to turn the amp on and off automatically when a signal is detected.
• Composite TV output. My standard clock board has composite output already on it. Can’t think of a good reason why I’d want to watch the prop on the TV, but what the heck, might as well utilize it. I’ve got cogs to spare.

The youtube video (music used was Royalty Free songs from danosongs.com):

First of all, being self-employed sucks. You get no paid vacation days. No paid sick days. Your insurance costs a fortune, so you probably buy a high-deductible plan. Your retirement options (IRAs, etc) are incredibly restrictive, unless you’re willing to hire an accountant and setup a plan. You pay 15.3% self-employment tax instead of the 7.65% FICA/Medicare that everyone else does. You deal with a massively overburdening tax system that’s aimed at big business, but constantly hits you. Politicians talk about “taxing the rich”, but few people realize these rich-targeted tax increases often hit the self employed.

So, I look at the HSA, and it seems like a good idea. I can save away some pre-tax money, and spend it tax-free on medical expenses. I have a bunch of dental work, some eye work, etc, coming up so this sounds like a good idea. An HSA requires a qualified “High-Deductible” plan, and I have already have a $2500 deductible health insurance plan (at $175/mo), so I ought to be all set, right?

Problem #1: My High-Deductible Health insurance plan isn’t a ‘qualified high-deductible health insurance plan’. As far as I can tell, the problem is that I’m allowed to pay a $30 copay for doctor visits. HSA doesn’t allow that. So, I have to change health plans to a different one. The qualified plan costs the same amount ($175/mo), raises my deductible by $500, and requires me to pay in full for doctor visits until the premium is satisfied (no nice $30 co-pays anymore).

My doctor charges $169 for an office visit. Under current plan I pay $30, under new plan I pay $169. That’s a difference of $139 per doctor visit. Of course, nobody wants to visit the doctor, but consider how quickly these visits might add up. You get a sinus infection, and need some antibiotics prescribed – a 5-minute doctor visit, but it costs me $169. What if you have an incident and need a couple of follow-ups? What if you need a referral to a specialist ($169 to the primary doctor, $169 for the specialist, and then who knows what the specialist will want to do the actual “work”). Losing the $30 copay for doctor visits sounds like a huge hit, and I would actually be paying the same damn thing for the insurance. That’s right, the HSA-Qualified plan costs the same amount as my current plan, but given 3 doctor visits I had this year, would have incurred an additional $402 in expense.

Well, the real benefit of an HSA is that I can write this off as a business expense, right?

Problem #2: HSA is not a business expense. It turns out that while I’m a business for the purposes of self-employment tax, I’m still an individual for the purposes of insurance. Thus, I can’t deduct HSA as a business expense. That already knocks off a large portion of the tax savings.

But, I can still save off my plain ordinary income taxes, right? Assuming I make it to the highest tax bracket, that’s 28%

Problem #3: 28% of $3050 isn’t that much money. 3050 is the maximum contribution I can make as a single individual. Assuming I make it into the maximum tax bracket of 28%, then I could save $854. Well, if I made those 3 doctor visits documented above, then I’d have already wiped out half of the savings by going to this new scheme.

Well, at least I can earn an investment return on the balance of my HSA, right?

Problem #4: HSA maintenance fee exceeds investment return. I checked with Bank of America. They pay a generous 1% interest rate (that’s actually quite good these days). But, they charge $4.50/mo maintenance fee. That’s $54 per year with no guarantee the fee won’t increase. 1% of $3050 is $30.50. Assuming I spent none of the money, I’d lose$23.50 in my investment the 12 months. Given that I’d probably be using some benefits, then it’s going to take multiple years to ramp up to the point where I’d actually be making a positive return on my investment. If I invest > $1000, then BofA does let me buy ’select mutual funds’ (whatever those are, probably mutual funds with high maintenance fees that pay a marketing fee back to BofA). That might sound good, but medical expenses are one of the few things you actually may need in emergency and really aren’t what you want to make long-term gambles on. Retirement is different because you might not need it for 30 years, but medical you could need tomorrow.

So, at least the money remains mine and I can spend it even if I change jobs, right?

Problem #5: HSA testing period. If you enroll in an HSA mid-year and make the maximum contribution then you’re subject to the HSA ‘testing period’. You have to remain in the HSA for one year. If you were to, for example, change jobs and become eligible for “real insurance” or wanted to change to a different health plan that wasn’t HSA-qualified, then you face a penalty. The penalty looks like it’s roughly 10% of each month that you expected to be qualified, but were not. Oh, and you pay back tax on those months too. So I have to have fortune-telling ability, and know that I’m going to remain self-employed for the next 12 months, lest I end up giving a 10% penalty (and tax) back to the government. Self employed people don’t have this perfect predictive ability; our needs do change.

So, in short:

1. My current $2500 deductible health plan doesn’t qualify, but my insurer is kind enough to offer me a $3000 deductible plan for the same monthly fee.
2. I don’t save that much tax, because I still have to pay 15.3% self-employment tax on the contributions. The maximum saved is at the top tax bracket of 28%, or $854 per year.
3. It’s going to cost me $54/yr maintenance money to have the HSA
4. HSA return is poor (1%, or gamble in the bond/stock market)
5. Loss of $30-copay presents a significant increase in expense, in my case it would have been $402 this year
6. Change of plan within the first year would incur a 10% penalty + tax, if a full contribution is made the first year
7. If I actually made 3 doctor visits ($402 extra expense) and also used the full $3000 deductible, then I’d lose $102 by choosing the new plan and HSA.  ($854 tax savings – $402 doctor visits – $500 additional deductible – $54 maintenance = -$102).

I suppose an investment adviser would advise that any money saved is worthwhile, but I think there’s too much risk inherent here. Maybe some qualified insurance person will find their way to this link and correct the error of my ways.

NOW, BACK TO ELECTRONICS-RELATED BLOG POSTS!!!!

Why Insteon?

Smarthome will enumerate a number of reasons why insteon is better than other technologies like X10. The crux of the matter is that X10 doesn’t have a retry mechanism (messages that are lost due to interference are lost) whereas Insteon does. Insteon doesn’t absolutely guarantee delivery as there are a limited number of retries, but it’s certainly much better than X10. Insteon also offers an automatic repeating function (devices that receive a message destined for a different device will retransmit it), and the ability to link multiple power phases using a RF link between hybrid RF/PLC modules. The end result is a system that’s much more reliable than X10 without the need for explicit repeaters, signal bridges, etc.

Another thing about Insteon that’s better than X10 is the addressability. X10 devices use two dials for house and unit codes. A module typically only responds to one code, and a controller typically only sends one code. Insteon modules have 24-bit addresses burned into them at the factory, and links stored in nonvolatile RAM. An Insteon module can be configured to respond to many different controllers, and a controller button can control many different modules. This leads to something called a “Scene”, whereby a single button on a controller can set a variety of lights or appliances to a set of configured states.

Configuration Methodology

There’s a couple of different ways to setup modules:

1. By running around the premises pushing buttons. You push and hold a button on one Insteon device, then run around pushing buttons on other Insteon devices to link them together. Lots of pushing and holding and movement from place to place.
2. By software. Using a program like Houselinc or Powerhome, you can program the Insteon modules remotely. Rather than having to manually pair them all by hand, you can drag and drop using a windows interface.

I’m going to use method #2 (software programming) whenever possible. The advantage of this is that it’s very easy to get a high level overview of the links between devices. These links do get complicated, especially when you start introducing devices called “keypadlincs” that have multiple buttons and can control and respond to multiple devices.

Type of devices

The sample configuration is going to use all of the following:

1. Switchlinc (dimmable). A standard paddle-like light switch. Pushing the top of the paddle turns a light on, pushing the bottom turns a light off. Pushing and holding the top or bottom will brighten or dim it.
2. Switchlinc (relay). Similar to the dimmable switchlinc, but without the dimmer feature. It’s handy for devices that cannot be dimmed like ceiling fans, motors, pumps, etc.
3. Keypadlinc. The keypadlinc comes configured in either a 6-button or 8-button configuration. These function as in-wall controllers for other devices. For example, you could use one button on a keypadlinc to run your front lights, another button to run your back lights, another button to turn the living room lights on and off, and a final button to run a ceiling fan. Each keypadlinc also includes a dimmer or relay (depending on the model ordered), so it’s possible to also control a load on the keypadlinc. This means a keypadlinc can easily replace a switchlinc.
4. Appliancelinc. These are traditional appliance modules. You plug it into an outlet, and then you plug the appliance into the module. It can then turn the appliance on and off. The functionality is similar to a switchlinc-relay, but in a portable module rather than an in-wall switch.
5. Lamplinc. Traditional map modules. Plug it into the wall, then plug the lamp into the module. Like the Appliancelinc, but supports dimming.
6. Motion Sensors. These are passive infrared detectors that can detect motion and control the other modules. Two obvious uses are occupancy sensors (to turn room lights on when people are in them) and security sensors (to turn outdoor lighting on when people are around).

Installing Switchlincs

Here we run into our first set of modules. The premises to be retrofitted had some leviton X-10 modules installed and the goal was to replace them with switchlinc modules. The switchlinc modules were just ever so slightly wider than the leviton modules and didn’t fit the electrical box! Here is a comparison of the two modules:

- insert pic here -

The problem is the type of junction box. Rather than having square corners, it had rounded corners. The switchlincs would not fit this box because of the width problem. Here is a picture of a typical box (this one has traditional paddle switches in it):

- insert pic here -

These are the sorts of issues that you might run into setting up Switchlinc modules in your premises. It probably makes sense before an installation to do a survey of the junction box, checking:

1. Make sure the boxes are wide enough.
2. Make sure the boxes are deep enough.
3. Make sure there is a neutral wire in each box.

Installing Motion Detectors

The motion detectors can be configured in two ways

1. By using a set of jumpers on the back of the module
2. By setting jumper #5 on the back of the module (software configuration) and then using Houselinc or similar software.

Again, we’re going to stick with our philosophy of using software to configure modules whenever possible rather than manually configuring and linking. So, we set jumper #5 and use the houselinc software to setup the module. Here we run into our first peculiarity.

The Motion Sensors will not listen for configuration messages unless they’re in linking mode. To initiate linking mode, you have to open up the cover and push the link button. Then you click the synchronize button in the Houselinc software and it’ll download your configuration (and links) into the motion detector. This is just plain silly. It’s a software-configurable device, but in order to configure it you must 1) take it down, 2) remove the cover, 3) push and hold a button, and 4) run to the other room and click a button in the program. Either that or I was really missing the obvious on these devices. At the very least, it needs to be possible to push the link button without having to remove the cover.

Integration with SmartLinc

Now that everything is setup on the physical devices (switches, keypads, etc) and in the Houselinc software, the next step is to figure out how to integrate Houselinc with the Smartlinc controller.

Smartlinc is more limited than Houselinc, but offers several advantages. First and foremost, it doesn’t require a PC be constantly powered on and running like Houselinc does. Second, it has some great iPod/iPad/Android integration features. Third, it allows access from any web browser. If you’re going to be traveling, you’d perhaps like to leave all of your home computers off, but still have control of your lights and other devices remotely. This is what Smartlinc is good for.

So, how do we get Smartlinc to recognize all of our Houselinc scenes? The process isn’t all that difficult and we can get by doing it all in software, without having to run around the premises pushing and holding buttons on switches. First we need to create some placeholders for the scenes in Smartlinc. We’ll create two rooms: Bedroom and Outdoor. In Bedroom we’ll add two devices: light and fan. In Outdoor, we’ll add Front Lights, Back Lights, and Side Lights. We don’t need to actually link these to devices yet, we’ll do that in a moment in Houselinc. What we do need to do is to figure out some scene numbers.

Go into each room in Smartlinc and mouse over the name of the scene. Your web browser should show in it’s status bar the URL (if not, click it and note the URL in your browser URL bar). In our sample household, the button for the bedroom light has a link to http://ipaddr/01-01-F and the bedroom fan as a link to http://02-01-F. The two numbers in these URLs are the room and screen numbers respectively (light = room1:scene1, fan = room2:scene2).

Now, we go into Houselinc to setup the links. First, make sure our Smartlinc device has been added to houselinc (if not, write down the device number and use the <add> button). If you expand the Smarlinc device, you’ll see that it has links for 15 rooms and 16 scenes per room. These correspond exactly to those numbers for the URLS. For the purposes of Houselinc, the Smartlinc device looks a lot like a Keypadlinc but with 240 buttons (15 groups of 16) instead of 6. Think of it as a super-keypadlinc connected to a web browser. Thus, If we drag smartlinc room1:scene1 into the controllers box for our ‘bedroom light’ device, then we’ll associate the light button in the smartlinc as a controller of the bedroom light. Be sure to also associate it as a controller of the buttons of any other keypads that also control that light, so that it controls the LED on the keypad. Houselinc will then synchronize these links, and our Smarlinc can be used to control our houselinc scenes. At this point you should feel pretty confident at dragging and dropping links, so this should be easy by now!

TED-5000 Interference Issues

Our little test environment also includes a TED-5000 whole home energy monitor attached to the main panel. The TED also communicates using PLC between the measuring unit that is installed inside the main panel and the gateway which is installed in a branch circuit (this is done to keep low-voltage wiring, such as Ethernet out of the main panel, and because wireless does not penetrate metal enclosures well). Unfortunately, the TED-5000’s PLC caused some grief to the insteon devices.

In particular, dimmer modules (switchlinc, etc) would experience a momentary flicker from on to off and back to on again at random intervals of about 30 minutes to a few hours. The precise reason for this is unknown, whether the switchlinc was misinterpreting TED communication as an Insteon command, or if it was causing the dimmer componets (for example,a triac) some issue. The solution is to isolate the TED from the rest of the household wiring.

This can be done using an X-10 XPF filter module, available for as little as $6 on ebay. Use the XPF to isolate the branch circuit that the TED gateway will be plugged into, as well as the TED’s MTU (i.e. The red wire fromt he XPF connects to both the black wire from the MTU and the black wire from the branch circuit; The MTU’s red wire is capped, and the MTU is put into 120V mode in the footprints software). An existing branch circuit can be used if one is handy. Whatever circuit you want to isolate should not have any insteon devices attached to it, as the filter will filter out Insteon signals as effectively as it filters out the TED signal. Think outside the box — circuits for dishwashers, garbage disposals, washers, furnaces, etc, may be on isolated circuits already. If you can’t find anything, then adding an additional dedicated branch circuit is another option, which is what we did in our case.

Once isolated by the XPF module, the TED no longer introduced Insteon interference, and the flicker on the switchlinc went away.

SmartLinc timekeeping

My smartlinc loses about 30 seconds to a minute per day. I don’t know why, as it as a DS1337 RTC. A couple of pictures: (click to make bigger). The DS1337 is the chip right under the battery backup.

There’s a couple of ways to solve the problem without having to do any modifications. In particular, if you have a linux box handy then you can create a simple cron job and use the following script:


#! /bin/sh

# script from Bruce (bmaw) at smarthome forums, see forum topic:
# http://www.smarthome.com/forum/topic.asp?TOPIC_ID=6597

# Set it on the SmartLinc
${wget} -q -O - "http://${smartlinc}/1?TD=${now}=1=falsefalse" > /dev/null


In this tutorial, I’m going to show how to interface a Dekatron tube to a Parallax Propeller microcontroller. This is similar technique to what I used in the Packetron-9000 project, although in that project I used mosfets. MPSA42 transistors are much cheaper and a lot easier to interface.

Circuit Description

Above you can see several things. On the top left, we have the high voltage power supply described here. The power supply was modified by substituting a 5.6k resistor for  R1 (the resistor between the pot and ground). This allowed me to get a bit of extra range out of the power supply since it takes about 425V to properly work the dekatron.

Below the power supply is a breadboard with a couple of current limiting resistors and a voltage divider. The voltage divider supplies (22/180)*425 = 52V that is used for the cathodes on the dekatron. The guides must be driven to at least 30 volts below the cathodes to make the dekatron count. -30V is hard to come by, but it’s much easier to just raise the cathode voltage a bit. 52V is close enough.

My original voltage divider used two 180K resistors for a total of 360K resistance on the anode. After experiencing a dekatron failure in a related project, I’ve raised the resistance to 1M. Better safe than sorry.

Below the voltage divider breadboard is of course, a dekatron tube. It’s a russian OG-4 dekatron tube, and is installed in a standard octal relay socket. These sockets are relatively cheap and easy to work with.

On the right, we have a propeller microcontroller from a propeller education kit. The Dekatron’s guide pins are operated using a pair of MPSA42 transistors. The emitter goes to ground, collector goes to the dekatron guide, and base is connected via a 22k resistor to the propeller’s IO pins.

Schematic

All of this is illustrated in the schematic below:

I’ve only illustrated the parts relevant to the dekatron interface — there’s some other mandatory propeller components like the eeprom, reset circuitry, crystal, etc that aren’t shown.

Program Listing

Below is the listing for the propeller program. It’s pretty simple, the guts of it are to pulse the two guide pins on and off. First, P1=On, P2=Off, P1=Off, P2=Off. Repeat that sequence over and over again and the dekatron will spin.

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000

  GUIDE_MS = 10
  STEP_MS = 250
  P1=15
  P2=14

PUB main
  dekaSpinTest

PUB dekaSpinTest
  dira[P1] := 1
  dira[P2] := 1
  repeat
      outa[P1]:=1
      waitcnt(clkfreq/1000 * GUIDE_MS + cnt)
      outa[P2]:=1
      waitcnt(clkfreq/1000 * GUIDE_MS + cnt)
      outa[P1]:=0
      waitcnt(clkfreq/1000 * GUIDE_MS + cnt)
      outa[P2]:=0
      waitcnt(clkfreq/1000 * (GUIDE_MS + STEP_MS) + cnt)

Youtube Video

Finally, here is a youtube video that describes all of the above, and more!

Clearly, something better is needed.

We need an indicator that one can tell at a glance exactly how much traffic is coming or going from the Internet.

We need 1960s vacuum tube technology.

We need dekatrons.

Thus, I give you: The Packetron 9000.

Four Soviet OG-4 Dekatron Tubes. Shipped to me from Odessa, Ukraine.

One Parallax Propeller microcontroller with ENC28J60 ethernet interface.

FOUR HUNDRED and TWENTY FIVE volts of pure DC power.

Mosfets, 8 of them, they’re not even supposed to work at 3.3V.

This device requires a youtube video to demonstrate its full potential.

Here’s a view of the internal components of the Packetron 9000:

The nice thing about this project is that almost everything was a surplus design from one of my other projects. In order from left to right, we have:

• Transformer and rectifier board. The transformer is a 12.6v center tapped. I full-wave rectified the 12V to use as a power source for the high voltage power supply, and then pulled off the center tap for powering the logic board. For reasons I’ll never understand (I’m sure it has to do with RMS voltage and calculus), this yielded around 18V and 8.6V.
• Logic Board. It’s a parallax propeller microcontroller with a ENC28J60 for ethernet. The nice thing about the prop is its multicore design. Two “cogs” operate the ethernet, two operate the dekatrons, two run an optional video out for debugging, and a remaining cog operates as a central controller. The Logic board is a leftover from my NTP clock project.
• Voltage divider and current limiter Board. The dekatrons need 300-500 ua or so of current. This little perfboard uses some current limiting resistors (I think I used a pair of 180 ohm resistors per dekatron, that’s probably a bit too much current). Experience a dekatron failure with only 360k resistance per anode, so I upped the resistance to 1M per anode. The current limiting resistors supply the anode power to the dekatrons. A voltage divider is used to derive about 30-60 volts DC for the cathodes. Technically the datasheets tell you to run the guides at -30 to -60 volts, but we can run the cathodes at +30 to +60 and the guides at zero and nobody will be the wiser. It’s all relative.
• High voltage power supply. It’s the standard power supply detailed elsewhere in my blog. I had to tweak the resistors a little bit to set a higher output  voltage of 425 volts. Also made sure the capacitor is suitably rated at 450 volts. I’d have preferred an even higher rated capacitor for safety, but 450v was the largest I could find.
• Driver board. Each OG-4 dekatron has two guide pins. These pins need to be pulsed in a specific sequence to cause the dekatron to count. I used IRF840 mosfets to do this. This presents a problem as the IRF840 does not drive reliably from 3.3 volt logic. I had two different brands of mosfet. The “made in china” ones entered a linear state driving the guide pins to approximately 56 volts (open state was measured at about 132 volts). The “made somwhere else” ones behaved normally, driving the guide pins to zero volts. The china ones had to be cut out of the circuit and replaced. Choosing something else (MPSA42 transistors would probably suffice, or alternatively choose a logic-level mosfet) would be a good idea. New board to try out MPSA42s are already on order from batchpcb.
• Relay board. If we simply turn the dekatrons on with all cathodes connected, then they’ll start up in some random state. The dekatrons have two pins for cathodes — Cathode_zero and Cathode_1_to_9. So, we can boot it up with only cathode zero connected. This ensures all dekatrons start pointed straight up. Then we kick on the relay and apply cathodes 1 to 9. Since cathode zero is already lit, activating the others won’t alter the state. This lets us bootstrap the cathodes in a known state.

So, how does this all work? The control module is implemented in a cog and does the following:

1. The propeller sends a constant stream of SNMP requests to my cisco router. These requests are for four counters on the WAN interface: in-unicast, in-nonunicast, out-unicast, and out-nonunicast. The nonunicast packets I presume are broadcasts as they’re arriving on the WAN interface regardless of whether legitimate work is being done. I suspect they’re DHCP or something similar from the comcast network or the neighborhood. out-nonunicast is effectively zero, so I optimized it out.
2. The in-unicast and in-nonunicast are summed to get the total number of incoming packets. The number of outgoing packets is simply out-unicast since out-nonunicast is zero.
3. I keep a circular buffer that holds the timestamp and count of incoming and outgoing packets. There’s 5 slots in the buffer.
4. Every time the buffer is updated, I compute the delta = (current_count – oldest_count), elapsed = (current_time – oldest_time) and rate = delta/elapsed. This creates a sort of average over 5 samples and smooths out a little bit of burstiness.
5. Depending on the position of the selector switch, I feed either in_rate, out_rate or in_rate+out_rate to the dekatron module, so that the dekatrons will increment at that frequency.

The dekatron module is composed of two cogs:

• The first cog loops at a specific frequency (as determined by the parameter passed to it) and increments a counter. For example, if there are 1000 packets per second, then the frequency is set to 1000 Hz, and the counter will be incremented 1000 times per second. The prop can handle this loop in spin up to a few hundred thousand Hz which is plenty for our purposes.
• The second cog wakes up every 1 ms and looks at the counter, checking each digit. If the ones digit has changed, then the lowest dekatron is kicked over a tick. If the tens digit has changed, then the next-to-lowest dekatron is ticked. Ticking a dekatron involves a simple sequence of G1, G2, ~G2, ~G1. A hundred microseconds between transitions is more than sufficient. The OG-4 dekatrons are only good to a few kilohertz, and that’s the reason for this added bit of complication. By updating every 1000ms, we guarantee we are never spinning a dekatron faster than one kilohertz. The user won’t really be able to tell the difference. The higher order dekatrons preserve correctness in counting, so the most significant digits are accurate.

The remaining cogs serve some utility functions:

• CRT driver. The standard prop video out driver.
• Updater. Takes the current state and outputs it to the video driver, for debugging. This could probably be integrated into the main loop, but it is kinda slow and affects timing, so it was easy enough to push it off to another cog.
• Ethernet driver. Harrison Pham’s proptcp driver, with a good deal of customization. I stored four static SNMP request packets in it (in_unicast, in_nonunicast, out_unicast, out_nonunicast) and send them out via UDP. UDP packets are demultiplexed and SNMP counters are adjusted accordingly. Wrote the UDP checksum and header stuff myself, was kind of a pain to get it right (involved some tcpdump’ing to a linux box to see where I’d messed up the checksums). Also wrote the ARP stuff myself a few years ago, as it did not exist in the proptcp driver at that time. Probably should rewrite all of my code to make use of the newer proptcp stack.
• SPI driver. Part of the proptcp stack.

Swingaxle

IRS

The excessive camber of the swingaxle can lead to a number of drive-ability problems, including an increased chance of rollover. Other advantages of the IRS:

• You can remove the transaxle without having to remove the wheels
• You can remove the axles and still tow the vehicle (good should you ever suffer a catastrophic transaxle failure in the field)
• Less opportunity for fluid leaks since the axles are not live
• In my opinion, IRS transaxle is much easier to tear out of the vehicle, throw on the workbench, and work on. Swingaxle is a large unwieldy mess.

Disadvantages include the need to maintain CV joints in addition to all the stuff you usually maintain. It’s another set of parts to wear out, and another source of potential expense.

As if converting from swingaxle to IRS isn’t enough, this article is also going to discuss conversion to an 002 Bus Transaxle. Why a bus transaxle? They’re generally more heavy duty than a bug transaxle. An 091 is even better than an 002, but the 002 is what we had access to. The Bus conversion will add a few wrinkles due to it’s slightly different configuration and need for different mounts.

Part 1 – Conversion from Swingaxle to IRS

Let’s get started, by putting the sandrail up on jack stands and removing the tires.

Swingaxle on jacks with tires removed

The next step is obviously going to be to remove the swingaxle, mount, shocks, spring plates, spring plate covers, etc. There’s nothing fundamentally difficult about that, but it’s a bit of work. We also removed the gas tank since it seemed prudent with all the welding going on. It would have been nice if we’d took pictures of all this, but we forgot.

Now is the time to talk about modifications to the torsion housing. An IRS suspension uses trailing arms in addition to spring plates to locate the tires. This is great, as this semi-trailing-arm design is what allows us to separate the suspension from the drive train (meaning we’ll be able to have a rolling chassis regardless of whether or not the transaxle is installed — try doing that with a swingaxle!). Problem is, the front of the trailing arms have something called ‘pivot brackets’. Since these brackets aren’t used on a swingaxle, they typically don’t exist, and we’re going to have to make them.

The brackets have to be placed in a specific location for your suspension to be aligned properly. To achieve this, we’re going to use a couple of jigs, purchased from Pacific Customs. These jigs bolt to the torsion housing, where the spring plate covers used to bolt, and precisely locate the pivot brackets. Here’s a picture of test-fitting one of the jigs:

pivot jig mounted to torsion housing

As you can see above, we put a couple of really long studs into the torsion housing to help us locate the jig. You can also see a little gap at the bottom, which means we weren’t quite there yet with the placing. Now, life would be very simple if all we had to do was jig and weld the brackets. Unfortunately, it isn’t quite so simple… The frame horns need to be cut away to fit the brackets:

hole cut in frame horn for pivot bracket

It’s a long and tedious process of cutting a little, test-fitting, cutting some more, test-fitting, cutting a little more, etc. In addition to the frame horn, you’ll probably also have to do some grinding on the brackets themselves (like most aftermarket VW parts, the brackets not only don’t fit, they aren’t even close to fitting). Take your time, and make sure everything fits just perfectly.

pivot bracket jig in final position for welding

As you can see, we replaced the temporary studs with bolts. No gaps anwhere… it’s ready to be welded. The better the job you did with cutting the frame horn, the easier the job welding. As you can see we left some significant sloppy gaps — those will end up taking a bit of work to fill in with metal. You want it all welded back up strong and secure. Below is what it looks like welded and painted.

bracket welded and painted

Now, repeat everything with the other side:

the driver's side pivot bracket jigged and welded

Ok, the hard part is all now behind us. All we have to do now is to assemble a standard IRS suspension. It’s time to go buy some parts:

• Trailing arms … used, from local VW shop
• Wheel bearings … pacific customs, new bearing set
• Wheel bearing misc … used, from local VW shop (spacers, end caps, bolts, etc)
• Stub axles … pacific customs, bug-to-bus-CV conversion stubs
• Spring plates … pacific customs, special plates for short torsion bars
• Spring plate covers … pacific customs, fancy stainless steel ones
• Disc brakes … CB Performance (no, you don’t need disc brakes, but it just felt wrong to install those ugly old drums)
• Urethane torsion bushings … pacific customs
• Urethane pivot bushing … pacific customs

Put it all together, and we have something like this:

trailing arms and wheel hardware installed

trailing arm passenger side

side view of trailing arm and spring plate

Note that there is still one remaining bolt hole that we’re going to have to drill in the side plate. Whether or not you need to drill one depends on which year trailing arms you get, and what type of spring plates. In our case, we waited until after we had done the final alignment before drilling that hole. It’s a great way to make sure your toe-in will be permanently fixed to a desired position.

This completes the IRS conversion — if you have an IRS type-1 transaxle, you can stop here and mount your transaxle, CV joints, axles, etc. If you want to use a Bus transaxle, then we have a bit more work to do:

Part 2 – Bus Transaxle Installation

You’re going to have to decide what kind of transaxle mount you want to use, because unfortunately bus transaxles don’t fit buggy chassis. There are several different options. The first is the Bugpack-style hard mount. It has a solid plate at the front and a solid plate at the back and a couple of solid straps. It’s good and cheap. The other popular option is called a “10 degree” mount and mounts your transaxle at a ten degree incline.

Why would you want it at a 10 degree incline? There are two reasons:

• It’ll give you more ground clearance by tilting your engine, which could be handy if you have an extra sump on your motor.
• It locates the shift rod in almost the right spot.

Wait… what? Nobody said anything about shift rods being wrong. Well, yes, the Bus transaxle locates the shift rod about two inches higher than a buggy transaxle. People have all kinds of solutions for this, from u-joint shift linkages, to offset couplers, etc. The two most popular solutions are to either use the 10 degree mount (which, by tilting the transaxle, puts it in almost the right spot), or mounting your shifter up higher.

I decided to go with the bugpack-style mount, and a relocated shifter box.

Bus-Into-Bug hard mount

Like most aftermarket VW accessories, be prepared for it to not fit quite right and require a bit of “adjustment” to make it work (don’t they measure things before they manufacture them?). There’s some left-right adjustment to get things centered. It my case, I think I also had to fool with the bolt holes a little bit. Also, there was a gap between the transaxle and the mount:

gap between mount and transaxle

As you can see above, I ended up inserting a nut between the transaxle and mount. It’s actually not a full nut, it’s ground down just a little bit, and I actually welded the little nut to the mount. Let’s call it a mounting boss rather than a nut-welded-to-the-mount. It sounds better. Anyhow, like I said, the plate now has a custom mounting boss.

Here’s a picture of the modified shifter box:

piggyback shifter box

See what I did there? It’s actually a shifter box mounted piggyback-style on top of the old shifter box. It works out just right. The good thing is, the way I built it, it can easily be unbolted, and the old shifter box could be used as-is if I ever wanted to go back to a buggy transaxle.

Part 1 – Tools

Let’s get started discussing tools. Unfortunately, rebuilding a transaxle is going to require a whole bunch of special tools that the average person does not have. Expect to spend a minimum of $400 to get yourself a pinion bearing retaining nut socket (69 and later) and a jig/basic tool kit. The jig is necessary to realign the shift forks near the end of your rebuild. Unfortunately, you can’t align the shift forks once it’s put together, so you need to use the jjg to align them, then disassemble the jig and finally reassemble the transaxle. While you can cut up an old case and make a jig out of it, this presumes you have an old case laying around.

jig

Unfortunately, I have to give a word of caution about this bugpack jig pictured above. Mine suffered from at least 3 different problems during the rebuild:

• The standoffs were the wrong length. With the little black plastic spacers added, they were STILL the wrong length. I ended up going to the hardware store and picking up an assortment of washers to pad them out to the correct length. Make sure to measure the case end to bearing seat distance in your transaxle case and compare it to the distance in the jig. Don’t assume the jig will setup this distance correctly.
• The mounting spot for the standoff for reverse (reverse gear rides on a standoff that mounts to the jig) is not in the correct place. The clearance between reverse and the pinion shaft was thus too tight, and reverse would not engage in the jig. Fortunately, reverse worked just fine once the transaxle was reassembled. Nevertheless, this problem made the jig useless to me for any reverse-related adjustments.
• There is no support for the back end of the 1-2 shift rod. The hole is at least twice oversize. I’m not sure if they expect a guy to fit a bushing in here or what, as there were no instructions. With no support, the rod is a bit wonky while trying to adjust it.
• Hole for the mainshaft was a little under dimension. It took some minor clearancing to get the mainshaft so it could spin freely.
• Given the above problems with things not being in the right spots and/or the right length and/or the right size, it makes me wonder if anything on the jig is positioned properly. Do I have confidence that it’s holding the clearance correct between main and pinion shaft? not really. There are lots of VW parts one buys knowing one has to do some final fitting adjustments, but a jig is not one of those things. A jig needs to be correct, it’s the whole purpose.

jig, showing standoffs

pinion nut spanner

leverage tool

pinion bearing retaining nut socket

On my year 002, the side covers thread in. Lacking the proper socket, I tried loosening it with a hammer and chisel as the haynes manual suggested. It was much easier to just bolt a metal bar to the side cover retaining bracket and use it as a makeshift tool:

makeshift VW 381/15 tool

In part 1 of the video, I cover the tools:

Part 2 – Major Disassembly

Now that we’ve covered the necessary tools, the next step is to get the transaxle removed from the vehicle and start the major disassembly. The following video covers the steps I took to break the case apart and remove the major parts from the transaxle.

Part 3 – Shaft Disassembly

Now that we’ve got the parts out of the case to the point we can work on this, it’s time to do the fine disassembly. In this part, we’re going to take the main shaft and pinion shaft out of the gear carrier, and separate all of the gears and other parts from the shafts.

Part 4 – Gear inspection with microscope

The particular problem we were having was the transaxle not wanting to engage first gear. So, the first thing I did was take a close look at first and the 1-2 slider. First gear doesn’t look all that bad in the picture below, but visual inspection of many of the teeth showed it to be worse than this particular picture. The leading edge was worn down a bit flat, and there were several teeth that had severe pitting.

First Gear synchro teeth

Next up is the 1-2 slider. It wasn’t as bad as first gear:

1-2 slider, 1st gear side

1-2 slider, 2nd gear side

Third gear looked really ugly, which is odd, because 3rd wasn’t having issues sliding into gear:

third gear drive teeth

In part 4 of the video, I show the gears being inspected in the stereo microscope.

Part 5  – Shaft Reassembly

to be done…

Part 6- Jigging and Shift fork setup

To setup the shift forks, you need a jig (see the tools section). Unfortunately I had a few “issues” with the bugpack. First off, it’s critical that the jig must setup your shafts exactly the way they will be setup in the case. Note that the pinion shaft is located front-to-back by the jig. If the brass spacers push the jig plate too far back, or too far forward, then your pinion shaft will be mis-positioned, and you will set the forks to the wrong spot.

What I did was to take my case and measure the distance from the end of the case to the surface where the pinion sits. If memory serves, in my case this was about 107mm. Your case may differ, so check it yourself (I’ve heard 106mm on the forums). Then, take the spacers from the jig kit and do whatever you need to do to make them work. I ended up stopping by the hardware store and picking up a selection of washers to pad the spacers out to the right length. Check, double-check, and triple check that you got this right.

Make sure to tighten down the pinion bearing nut (I used one of the aluminum spacers right before the nut; click the picture below to zoom in and see). You don’t need to torque it to spec. Just get it tight to make sure there is no play and the pinion shaft is located properly. Your shims should be installed. Also make sure your mainshaft bearing is sitting where it’s supposed to be. Check, double-check, and triple check your measurements. Remember that you’re aiming to reproduce the configuration exactly was it will be in the transaxle case.

Here is a picture of the setup jig:

Transaxle in Jig

Once you have it in the jig, you’re going to test the shift forks. Shift into first (or second), tighten down the 1-2 shift fork, feel the play/wiggle in the slider when it’s engaged. Then, shift it back to the other end and feel the play. What you’re aiming for is the same feel for both first and second. Once it’s equal, neither side should be pushing in hard. Repeat the whole thing with the 3-4 fork and slider. I found it to be much easier than anticipated. Make sure to torque the bolts to spec once you’re done — you don’t want to forget and reassemble your transaxle with loose shift fork bolts!

Here is a youtube video of the gear train in action:

Part 7 – Final Reassembly

I didn’t actually take any pictures of the final reassembly because by and large it’s a process of reversing most of the stuff you did during the disassembly. I highly recommend you purchase something like the Long Enterprises transaxle rebuilders course (see http://www.longenterprises.com/), it’ll tell you a lot of small things to do during the reassembly process that I forgot. In particular, you’ll need to pay some special attention while putting the gear assembly back in the case — there’s some work to do with heating the case, lining up the pinion bearing, etc. The long CD explains it very well and in detail, and I was surprised about how well the technique worked.

So, what I really wanted was a Chumby with an ambient light sensor. So…. I set out to make one:

Yes, using a propeller professional development board is a little overkill for the project, but it’s what I had on hand and will suffice until I can make something a little smaller.

The first part of the hack is a small program for the prop that samples a photocell every so often and sends either a “L” or a “D” out the serial port. The photocell is connected in series with a 0.1uf capacitor to pin 23 on the prop, and the PDB’s serial port’s tx is connected to pin 21. The PDB’s serial port is connected via a USB/Serial adapter to the USB port on the back of the Chumby. Here is the prop program:

OBJ
  serial: "FullDuplexSerial"
CON
  _clkmode = xtal1 + pll16x
  _xinfreq        = 5_000_000
  'settings on scott's PDB board
  photoPin = 23
  txPin = 21
  rxPin = 22
  ' settings on scott's USB proto board
  ' photoPin = 0
  ' txPin = 30
  ' rxPin = 31
VAR
  long parameter
  long time
  long wtavg
  long dark

pub main
  serial.start(rxPin, txPin, 1, 115200)

  init_sensor

  repeat
     read_sensor

     parameter := wtavg

     if wtavg > 200000
        dark :=1
        serial.tx("D")
     else
        dark := 0
        serial.tx("L")

     ' do some work
     waitcnt(clkfreq/1000*100 + cnt)

pub init_sensor
  wtavg := 0

  ctra[30..26] := %01000
  ctra[5..0] := photoPin
  frqa := 1

pub read_sensor
  time := (phsa - 624) #> 0
  wtavg := (wtavg * 90 / 100) + time/10 

  dira[photoPin] := outa[photoPin] := 1
  waitcnt(clkfreq/100_000 + cnt)
  phsa~
  dira[photoPin]~

The second part of the hack is a small bash script that runs on the chumby. It reads from a USB-Serial adapter at /dev/ttyUSB0. If it reads an “L”, then it sets the display to bright. If it reads a “D”, then it sets it to dim.

#! /bin/bash
stty -F /dev/ttyUSB0 cs8 115200 ignbrk -brkint -icrnl -imaxbel -opost -onlcr -is
ig -icanon -iexten -echo -echoe -echok -echoctl -echoke noflsh -ixon -crtscts -hup
while [[ 1 ]]; do
  ch=`head -c 1 /dev/ttyUSB0`
  if [[ $ch == "L" ]]; then
      echo 100 > /sys/devices/platform/stmp3xxx-bl/backlight/stmp3xxx-bl/brightness
  fi
  if [[ $ch == "D" ]]; then
      echo 30 > /sys/devices/platform/stmp3xxx-bl/backlight/stmp3xxx-bl/brightness
  fi
done

I placed the script in /mnt/storage/dimmer.sh on the chumby and started it with:

nohup bash /mnt/storage/dimmer.sh < /dev/null > /dev/null &

There are ways to automate execution of the script on startup and I’ll probably do that. In the meantime, my chumby is battery-backed-up during outages, so it’ll never get rebooted anyway.

A video of the hack in action:

Using the PDB’s on-board serial-usb converter

A short follow up… In my tinkering I was also able to use the PDB’s on-board serial-usb converter by using pins 30 and 31 for tx/rx. These are the same pins used by the programming interface. It also works fine using a prop-plug for serial-USB conversion. So, one could probably implement this with as few components as:

propeller microcontroller
eeprom
prop-plug (ttl-serial to usb)
crystal
3.3v power supply
photocell
0.1uf capacitor

Everything needed to do it except the photocell is in the propeller education kit… I might try to prototype it on the PEK, just to show the minimalist approach. The photocell actually used to be in the PEK, but was removed due to ROHS restrictions. Nevertheless I got mine before then. I guess I like to live dangerously.

Update – Implemented on Parallax Propeller USB Proto-Board

The USB Proto-Board is a great deal, and only costs $25 – $30 depending on quantity. It already has almost all of the components we need, including the propeller microcontroller, usb to serial, voltage regulators, etc. The only components needed to be added are the photocell and 0.1uf capacitor. Here is a picture of the circuit prototyped out on the proto-board:

The remaining thing that needs to be done is to turn off the annoying blinky light on the USB-Serial. The proto-board uses an FTDI FT232R chip, and FTDI produces a tool called ft_prog that can be used to reconfigure the lights. I set the output for C1 to CBitBangI/O and that appeared to turn off the LED. You don’t need to mess with C0, as that LED is only used when data is received by the prop, which only happens (in our case) during programming.

Using the USB proto-board, we have a nice little implementation of the circuit.

Smart Cover

The first thing to talk about is the iPad 2 Smart Cover, which I find just doesn’t stay closed. Here’s a picture:

… and a video:

The smart cover is neat. It hooks up to the side with little magnets, I just don’t find that it works very well.

Getting optical output – attempt #1

I have a fancy $630 ipad, why would I want to listen to crappy analog output from it? It’s the latest and greatest technology, however it has no toslink or sp/dif port.

What I do have is a HDMI out adapter that I can use with my HDTV. So, I think to myself…. HDMI has digital audio, all I need to do is get that digital audio into a format I can use, like toslink optical. Can’t be too hard, can it? So I google around and find a product that looks like it will do it, something called a “HDMI audio extractor”. It has HDMI in, toslink out. There’s also some other outputs, including analog out and a passthrough HDMI output. Surely, this ought to do it? Well, no. Turns out it only works in a passthrough configuration. If I don’t hook a TV up to the HDMI output on the HDMI audio extractor, then nothing will come out of the optical output.

Looking around for other options, I see a couple of other devices, mainly docks, that will output digital audio. They range from fairly cheap to really expensive. A bunch of other forum threads talk about using the camera adapter with a USB audio adapter. Yuck, that doesn’t sound pleasant.

Finally, I stumble on something called “airplay”. It seems the ipad is able to stream it’s sound output to a device called an “airport express”. I’m not sure why this was so hard to figure out, but it was fairly nonobvious to me. As an added benefit, it will also be a wireless solution.

Getting optical output – attempt #2

So I decide the way to go here is to use an Airport Express. The airport express is this contraption that looks like a fat wall-wart with an ethernet port, usb port, and 1/8 audio jack in the side of it. Supposedly, the 1/8 audio jack is a fancy combination analog-digital jack with a little laser sitting behind it that will output my optical digital output. I order a couple of mini-optical to toslink cables.

So, like any wireless piece of equipment, it has to be configured to my network. I load up “airport utility”. It can’t find the airport express. Not surprising, since my desktop uses a wired connection. On a whim, I try to plug the ethernet cable into the airport express to see if it can find it over a wired connection. No such luck. Off to the laptop it is.

The laptop is more productive, “airport utility” finds it’s device and warns me that it’s going to mess with my network settings to configure it. I figure… what’s the worst that can happen? Well, it manages to corrupt the laptop’s network settings in some incomprehensible way. I spend about 30 minutes repeatedly trying to re-enter network keys and whatnot before finally giving up, deleting my wireless and re-adding it.

Now I decide to change the airport express’ IP address to a static IP, because I’m a static address sort of person. For some reason, as part of changing the airport express’ IP address, airport utility once again needs to corrupt my laptop’s network security settings. Delete/re-add connection.

Then it says it found a firmware update (gee! that’s easier once I fix the laptop so it can talk to the internet). So I figure, sure, I want my airport express to be the best airport express it can be, so I update the firmware. It changes the airport express’ IP address to 169.254.171.162. I have no idea where this address came from, it’s not on my subnet, not reachable from my subnet, and not something I ever typed. I change it back to the static IP I wanted (once again, airport utility decides that in order to update the airport express, it must corrupt the laptop’s network settings). Delete/re-add network connection. Surprise, the IP is still set to 169.254.171.162 (I’d still like to know where this is). I give up and just turn the frickin’ thing back to DHCP. Apparently the new firmware must not be up to the task of something so fancy as a static IP address.

I decide that “base station 6b66b” is probably not my favorite name, so I give it a better name, like “Airport Office”. This once again causes airport utility to damage the network settings on the laptop. Delete/re-add network. Now my airport express has a reasonable name. Apparently changing any setting on the airport express also requires airport utility to do some unspeakable act of perversion to the laptop’s network settings.

Anyhow, *FINALLY*, we grab the ipad and magically a dropbox has appeared next to the volume control, giving me a choice of speaker selection of “iPad” or “Airport Office”. Success. I plug the Airport Express into my minidigi/miniamp using the toslink and mini-optical adapter and at long last, we have digital output from the ipad to a digital amplifier. Kind of a long way getting here, but it’s done.

The sirius/XM player also plays through airplay (just set the speakers via the ipod app first). Even other programs, such as games, are sending their audio to the airport express. I haven’t verified if this is true of all apps.

Complaining about the iPad Sirius/XM app

The app sounds good, but have a number of problems that should be simple to fix but haven’t.

1. It times out and shuts off if the iPad is idle for a while. The iPad doesn’t shut off itself, just the silly app, poping up a dialog box asking if you want to continue. This sort of invalidates the whole concept of using this app with airplay if you have to wander over every so often and restart it.
2. If there’s the slightest hiccup with the stream, it pops up a dialog box asking you to press ‘ok’ to reconnect. DUH! Just reconnect already, don’t ask me if you need to reconnect.
3. The iPad being a wireless device, isn’t going to have perfect connectivity, especially in neighborhoods like mine where there’s a ton of competing wifi routers. The occasional connectivity hiccup will occur, resulting in the confirmation dialog mentioned above.
4. Sometimes an error occurs that is so egregious as to cause the app to want to reset the authentication information. In this case, the app doesn’t automatically use the stored name and password, so you have to retype your sirius ID and password. Annoying.
5. A couple times it’s popped up a dialog complaining that someone else is using the stream (they aren’t), and disconnects me, requiring a full reconnect with password re-entry. I suspect the silly app is reconnecting, and detecting it’s own connection as another user. Alternatively, it could be wifi migration (I have two routers to cover the house).
6. The app has froze several times while ‘checking credentials’, requiring the app to be killed and re-started (and the name/password retyped, again).
7. At least once it has forgot all of my favorites and I had to re-add them.

These aren’t big things to fix, a lot of it can be done by just making the app a little more robust and auto-reconnecting on errors. Check the reviews of this app in the appstore and people absolutely hate it due to the reliability issues. You’d think sirius/xm would have the resources to make it right.

I ended up giving up on the Sirius/XM iPad app entirely. It’s just not reliable and the inactivity timeout is a total pain in the butt. So, what I did instead was to use a program called ‘airfoil’ with my own xmicroplayer software. Xmicroplayer can run for days or weeks without experiencing a hiccup. I have an existing Linux box that I run various virtual machines on with VMWare, so it was easy to run yet another VM, this time running Windows XP and install airfoil + xmicroplayer in it. The plus is that this consumes no additional resources around the house; the VM server was running all the time anyway. One complication was that airfoil was a bit perspective about connecting from inside the XP VM — for some reason I had to create the VM under VMWare on my Windows box, suspend the machine, copy it over to VMWare on the Linux box, and then restart it. If the XP VM was rebooted on the Linux box, then airfoil would start throwing firewall errors. As long as I keep a powered-on checkpoint set, it’s easy to restart the VM in the state where it’s working. I suspect there’s something interesting going on here, but I lack the desire to look into it further, as now it’s working, convenient (Sirius/XM always on and playing), and extremely stable.

I’m even thinking about getting a couple more Airport Expresses and installing them on speakers in other locations. Supposedly airfoil can stream to many things at the same time.

Download Link -

version 0.1: pytivo-sirius-0.1.tar.gz

Limitations -

This plugin is extremely beta. Meaning, I got it work well enough that I
can listen to “80s on 8″ and that’s all that’s really important to me.
Things that are known to be broken include -
* Linux only
* Does not with Windows (in case you missed the line above)
* error-checking is virtually nonexistent. If something is broken,
you’re probably screwed. I hope you know python.
* the “play” page shows a bogus duration of 10,000,000 milliseconds
* the “play” page shows “unknown” for all other fields
* song title and artist information is not displayed or updated
* leftover named pipes may be left in /tmp
* orphaned mplayer and/or ffmpeg processes may get left around

Basically: IT WORKS FOR ME. It may or may not work for you.

Acknowledgements -

Pyxis: much code was used from the Pyxis online player, https://github.com/Kasuko/pyxis

Sipie: precursor to Pyxis, http://sourceforge.net/projects/sipie/, http://ionshard.com/pyxis

PyTivo / wmcbrine: I used the music plugin as a basis for this plugin from the wmcbrine distribution, https://github.com/wmcbrine/pytivo

Prerequisites -

1) You must have ffmpeg installed
2) You must have mplayer installed
3) You must have an mp3 encoder installed for ffmpeg (I used liblamemp3)

Those things listed above are actually important. You should check them.
Getting liblamemp3 working with ffmpeg was nontrivial for me. I had to do
the following:
1) build liblamemp3 from source and install it
2) copy lame libraries from /usr/local/lib to /usr/lib
3) configure ffmpeg with –enable-liblamemp3
4) build ffmpeg from source and install it

Installation

Everything in this directory should go into pyTivo in plugins/sirius

Configuration

Add a section to pytivo.conf that looks like this:

[SatRadio]
type = sirius
path = none
username = <put your sirius username here>
password = <put your sirius password here>

Also, add a path to mplayer to your [Server] section:

[Server]
… other pyTivo stuff
mplayer = /usr/local/bin/mplayer

Troubleshooting -

If and when something goes horribly wrong, look at the console output
and try to figure out what it was.

The Tivo music player is very fragile. Failure of a stream can occasionally
cause it to fail to the point where reboot is required to get it to work
again.

Make sure your ffmpeg has MP3 encoding support (liblamemp3, etc)

Make sure your sirius username and password are correct

Try downloading pyxis and see if it’ll work for you (it’s a command-line
Linux sirius player)

Future Plans -
None, really. I don’t have much time.

Song titles/artists would be nice.

This probably should be setup on one of them fancy git respository things.