How-To: Design your own iPod super dock (Part 1)

Look for resident hackers Will O'Brien and Eliot Phillips (plus many other crazy projects) April 22-23 at the Maker Faire in San Mateo, CA!

This one goes out to everyone that has an iPod or two laying about and an itchy soldering iron and thinks that the standard USB or Firewire dock just isn't quite good enough. The tiny thirty pin dock connector on the bottom of later model iPods contains quite a few connections and we want to take advantage of all of them: audio, video, serial, USB and Firewire. Today, we're bringing you part one of a How-To series on designing and building your own iPod super dock.

In this first part we'll be shopping for parts and preparing to design the super dock. The idea of building a dock with every connection available has been around for a while. It came up on the iPodLinux forums long ago and more recently a prototyping version was featured on Hack-A-Day. To find out just what the dock connector has to offer, we checked out pinouts.ru. Twenty five of thirty pins on the connector are used to deliver line level audio in, out, composite video out, a TTL level serial port, 3.3 volts out (handy for powering accessories), Firewire and USB.

The most challenging part to acquire is the actual iPod dock connector. Others have sacrificed cables, but new connectors are easier to work with. We picked up ours from Ridax on the iPodLinux forums, but lately Spark Fun Electronics started to carry them. (Spark Fun is out of stock today, but they assured us that more are coming in very soon) The connector we used is actually designed for making cable assemblies. The tabs are very small, and you'll probably turn into Smeagol go nuts trying to solder to them.

For the rest of the connectors, we visited Mouser electronics. Here's what we bought (Mouser's part numbers are listed):

• 538-53460-0621 6 pin 1394 PCB Connector
• 571-7877801 'B' USB Connector
• 161-4223 3 way RCA Phono Jack: Red, White and Yellow
• 152-3309  D-Sub 9 pin Connector
• 161-0096-E Red PCB Phono Jack
• 161-0097 Black PCB Phono Jack
  

Firewire and USB were pretty easy, we just searched for PCB mount variants of each. The 9 pin D-Sub connector is for the serial port. For audio and video out, we selected the three connector RCA jack with the red, white and yellow connectors. Mouser was out of the dual read an black RCA connectors, so we bought a single red and black (ok, it should have been white) one to finish the order up. We already had blank printed circuit boards and some MAX 232s and 233s in our parts bin to convert the TTL level signals to RS-232 serial. Oh, and you might want to season your recipe with a power connector or two.

To try our hand at soldering wires to the tiny connector, we made this handy travel charger just before a long, long, long plane ride. (The TSA guys actually laughed at it) Trust us, wiring this up took some patience. Forum user holto2go suggests placing a small piece of paper between the pins to ease soldering.

Because we want to use all of the pins, we decided to mount the connector directly to a pc board. A small screw driver was used to slightly spread the pins of the connector, and it fit very snugly around the edge of our board.

We considered using a fine tip sharpie to lay out the connector lines, but there's still alot of  board design left to do, and it's not very clean looking. In the end, we decided to lay out the custom connector in the latest version of our favorite freeware layout software: EAGLE.

To get started on the custom connector we measured the pins of the connector with our digital calipers. It's pretty challenging to measure the tiny connectors with much accuracy, but our measurements gave us a great place to start. We're going to skimp on some of the details because Instructables has a nice how-to on making your own parts in EAGLE.

To get the width of the pins just right, we printed out test rows with our laser printer and compared it to the pins on the connector.

We found that a .016 inch thick SMD pad was the right width, and starting with a grid size of .0205 inches we made test layouts of 15 pins, printed them out on a laser printer and compared the width to the actual part. Through a few iterations we settled on a grid that was .0195 inches wide. To provide plenty of surface area, we made the pads a generous  .140 inches wide. The pads alternate red and blue to indicate the top and bottom of the board. To make it look good, we added an approximation of what the dock connector looks like. Lastly we numbered the pads in order with the name command.

Next we made a simple schematic layout. It's just a box with the 25 active connector pins. Then we named each pin. We did a couple of repeats, because EAGLE doesn't want to link a schematic pin to two physical pins.

To bring together the symbol and the package layouts, we created a new device called the ipod-dock-connector. Within the package definition we associate the pins on the physical package with the pins in the schematic version. Now all the really tedious stuff is finished and we can start laying out the actual connections.

If you want to start playing around with your own dock designs, you can download the library we created for EAGLE here. Just place it in the "lbr" directory under the main EAGLE program directory. We'll continue the project in next week's in Part II. We'll be designing the dock and laying out the board using EAGLE. From there we'll make our own PC board and complete the super dock faster than you can say "iPod on fire."

[Coolwave @ Apr 18th 2006 7:25PM]

I'm sure many of us have thought about doing something like this... I hope part 2 or even part 3 has info about controlling the ipod through the dock. I've always dreamt about a super dock in my car with buttons on the stearing wheel for controlling the ipod and who knows what else could be possible with a custom dock like this.

[Will Shepherdson @ Apr 18th 2006 7:29PM]

Great! I can't wait for the next part...

[Taylor @ Apr 18th 2006 8:36PM]

Just out of curiosity, did you try to measure the distance in between just 2 pins, or did you measure the distance across an entire row and divide by the number of pins? That just came to mind...

But hey, cool writeup! Too bad I have a shuffle...
-Taylor

[firepyroandy @ Apr 18th 2006 9:12PM]

I ordered some of these same connectors (from ridax < THANKS) Not a week ago I put a similar project together. I used one to build a cable for my car, not only does the ipod charge (without a transformer) but it plays over my pioneer head unit without the sucky sound quality of FM transmitters. All one cable, and the only cost was the connector itself. I did not even need to buy one of those Aux. input boxes for my pioneer... I used http://stereophonik.com/gutterslide/IP-BUS_Hack/

Works flawlessly!

I did spend all day soldering those connections though!

BTW- You can remove the pins! just use a gentle touch and (preferably) rubber coated needle nose pliers. I had to resolder many of my connection because the pins themselves kept breaking.

[vonage @ Apr 18th 2006 10:08PM]

This is great. I have been wanting to do this for a while and now i can. I cant wait for the next part. Thanx alot

[Timmay @ Apr 18th 2006 10:14PM]

This could be a fun project. I have a 3rd Gen and my gf has a Nano. I would love a cradle that could do everything and wasn't $99 like crApple is charging.

Timmay

[Nate MC @ Apr 19th 2006 2:20AM]

I had the same problem as firepyroandy and kept breaking pins. I've never etched a PC board but I think it's about time to learn.

Always need more money to buy more tools.

[Gav @ Apr 19th 2006 5:01AM]

I built an iPod car dock into the ashtray of my car. But this I used a Belkin car charger with line out, that I striped down.

[william skeaping @ Apr 19th 2006 8:57AM]

Does this mean that you could plug Ipod(s) into a circuit bent casio synth/Keytar and make things go totally loopy?!

[Brendon @ Apr 19th 2006 1:00PM]

Here is the link to the CAD software http://www.cadsoft.de/. We had to use the Eagle Board Layout software for my senior project. It is an ok app it just has a lot of odd quirks that take a little time to get used to.

[Ale @ Apr 19th 2006 1:30PM]

for parts I was thinking using those super cheapo Cellboost charger http://www99.shopping.com/xPO-CELLBOOST_CELLBOOST_Instant_Power_for_your_iPod_or_iPod_Mini they only cost about 8 bucks in radioshack, or riteaid, can they be disected and reuse the connector?.
good thing that you guys came out with the pin layout.

[firepyroandy @ Apr 19th 2006 4:30PM]

No. 11 - Ale

I dont think that this "CELLBOOST" for the iPod will have all the pins you will want for a full blown dock connector.

Just order a bunch of them off of RIDAX, use what you can, and sell the extras for profit :)

[jeht @ Apr 20th 2006 4:10AM]

Coolwave:
to remotely control the ipod would more likely be through the connection next to the headphone jack, which is only a 4-pin out, so it shouldn't be hard to figure out

[mitchjs @ Apr 20th 2006 12:10PM]

i got a simpler solution then all this
check out my forum
http://www.rush2112.net/phpBB2/viewforum.php?f=7

its IPOD Dock talk only...no other ipod junk

also, u have to join to see the pictures
but what i did was design a cable and had it made in china... i got lucky i met the right person, normally they want 1000 pieces, i got 100

i also designed a pc interface, and wrote a nice ipod explorer software... all there is my forum

i have all the commands in the software, its to aid with microcontroller development, which i already did a IPOD to Sony XES interface :)

Still to this date the IPODLINUX wikki is backwards
correct dock pinout is on my forum
and more details there


mitch

[Ridax @ Apr 20th 2006 3:01PM]

mitch: I know that the pin numbering that has been documented through reverse engineering has the pinout backwards compared to the one you have. As long as you specify how you number the pins, I don't see why it should matter that much.

jeht: You can remote control the iPod through either the headphone jack/remote connector (on pre-nano versions) or the dock connector.

[Mark Fleser @ Apr 20th 2006 4:20PM]

Will the female connectors from the stores work in the same housings as the male connectors. I just want to make a simple extension and want it to look good, otherwise I'll have to mod something out of plastic.

[mitchjs @ Apr 20th 2006 7:50PM]

of course Ridax, but the people who made the connector define where pin 1 is, someone change the wikki, my DATA is right from APPLE!

mitch

[Ridax @ Apr 21st 2006 1:13AM]

mitch: I feel you are just confusing people when you say the iPodLinux page is wrong. The pinout documented there is correct, as they also have documented how they number the pins (although the description is a little weak on this). It doesn't matter how you number the pins and as long as you just look at the iPodLinux documentation, and not the official Apple docs and mix the two, it doesn't matter.

mark: The female connectors will not fit in the male covers.

[Ridax @ May 2nd 2006 10:51PM]

With a minor modification to the female connector, it will fit quite OK in one of the covers. The connector head needs to be glued into the cover, but it works quite good. The combination is now available for order at http://www.ridax.se

[indigo @ Sep 11th 2006 10:57PM]

I'm trying to build the travel charger you show in the picture above. I bought the connector and I have all the necessary supplies, and the pinout from:
http://pinouts.ru/Devices/ipod_pinout.shtml
but the only thing I've managed to do so far is make the ipod screen go black. Is it as simple as soldering one wire to ground the other to the a power input or is there a step I'm missing? I tried many different combinations of the grounds and power inputs listed while hooked up to a power supply, and none of the combos make the little guy charge. I have an old 10GB ipod. Any suggestions?

[Will O'Brien @ Sep 12th 2006 12:51PM]

Yup, it's that simple to make. There's an easy way to prevent shorts - grab your pliers and remove all the pins you don't need.

I use a 15w weller iron with a .5mm (or so) tip that I beveled with my dremel tool for an even finer point.

Will

[Matt @ Mar 4th 2007 10:57AM]

Hello,

Does anyone have any idea how to connect the connector (which pins) so that I can use my car's 12v battery to charge the ipod and also which pins for left, right and screen so I can connect this to my aux input on my car radio.

Many thanks in advance

Matt

[sabari @ Apr 9th 2007 3:37AM]

I want the over all circuit diagram of ipod

[tom925 @ Sep 23rd 2007 12:06AM]

just found the answer to the female ipod to mini jack adapter at RIDAX

[kendall rosado @ Oct 23rd 2007 10:41AM]

hey, i was wondering, could the serial output be used to link the ipod with a computer that does not have usb?

[Shillu @ Dec 12th 2007 4:13AM]

I have a iPOD docking connector board. When I place the nano iPOD into the docking station, it sez that" it's waiting for a video accessory to be inserted" Any comments on this???

[Pradeep SS @ Feb 6th 2008 4:04AM]

Can i have complete circuit diagram of iPOD and its charger circuit diagrams.