Hacking an inexpensive dock to toggle Desktop or Car dock modes

*** Another update ***
The 4.2.2 firmware appears to be missing the desktop dock mode entirely. The phone does not go into landscape mode and no dock launches.

*** Another update ***
The 2.2.1 firmware appears to be missing the desktop dock mode entirely. The phone goes into landscape mode but no dock launches.

Nothing I can fix, sorry.
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*** IMPORTANT UPDATE ***
It has been brought to my attention that this may only work for the US version of the HOX, and not for the international (quad core) version.

See this post in the thread: http://xdaforums.com/showpost.php?p=35485317&postcount=20
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So, after getting used to my Thunderbolt having a nice HTC dock that triggers Desktop mode, I was very disappointed to find nothing yet on the market for the AT&T One X. instead of returning the inexpensive dock, or messing around with software, I rolled up my sleeves and made it happen.

Originally I started making a breakout connection for the USB thinking I'd build a powered bluetooth speaker into the dock but then I realized I had too many projects going on. That's why the tiny breadboard is in the pictures - its part of the abandoned breakout. It's not needed at all, you could safely tape or heatshrink these 1/4 watt resistors for this application.

Also I realized after I started splicing that I needed to pare back more of the insulation, if I had to do it again I'd give myself more room to work with.

In my particular dock, the cable shield is not connected to port shield but it is used as the ground.

Pin 5 (ground) cable shield / black
Pin 4 (ID) Black wire
Pin 3 (Data +) Yellow
Pin 2 (Data -) White
Pin 1 (+5V DC) Red

The signal to go into dock mode is triggered with a resistor between pins 4 and 5.
10kOhm triggers auto dock mode
68kOhm triggers desk dock mode (also, a 47kOhm triggers desk dock mode)

Starting in Car Dock mode allows a toggle to Desk Dock with the switch, but the phone doesn't toggle back to the Car Dock from Desk Dock when switched back.

Not the point, at any rate - the only reason I did this was because I had the two-pole switch and both resistors handy.

The dock:

The underbelly (pull off the rubber feet gently)..

If you don't pull off the feet, you won't get the hidden screws.

The top will come off easily. Now you can push the bottom out.

The bottom has a steel weight.

Gently pry the cable out of the base. It lifts out.

Now you can unscrew the other end.

This is how I tested the resistors. Be VERY careful if you do this - the pin can break the wire. For such a tiny wire you need to pierce the side of the insulation.

Proof of concept.

I actually only had a 68.1kOhm resistor handy, it works fine.

Tie the ends of the resistors together to the shield. Tie the center of the switch to the ID wire.

Shrink wrap, tape, or otherwise insulate the connections. TEST FIRST, then reassemble - install switch....

Put it all back together....


Fullsize pics here:
https://picasaweb.google.com/ModemJunki/OneXDockHack#

See it in action! (not sure how to embed YouTube properly...)
http://youtu.be/tZ0Mom1wZq4

nitrous² said:

Looks awesome!! But shouldn't this be posted on Hardware Hacking forum?

Sent from my HTC One X using xda premium

Click to expand...

Click to collapse

Thanks.

You're probably correct. I'm not a hardware hacker by habit, so I didn't know that forum existed.

Perhaps a mod will move the thread eventually.

Skanob said:

Just a quick question, on what PINs did you connect the resistors? I couldn't see where through the pictures.

I wonder if this will work for the Desire S..

Edit.
Found the answer on the video. Thanks again.

Click to expand...

Click to collapse

Thanks for catching that. I added the description for which pins to bridge.

No idea about the Desire S, but it seems multiple HTC phones share common triggers.

xSilv85 said:

I suppose it will work for the international One X too.

Did you have tested with other values of resistance or it needs to be 1000Ohm and 6812Ohm?

Click to expand...

Click to collapse

I tested with some other values but only 10k, 47k, and 68.1k (really should be 68k) worked. I can't give more details about other values tested at the moment as I'm on holiday in the Caribbean and I live near Chicago in the USA

But I used the working values based on searches on the forums for other HTC devices.

Skanob said:

Thanks man. I'm about to buy this and give it to the GF as she has the one with the One X and I have the Desire S (yeah, go figure ). And thinking about modifying the Dock like as you did to make it easy for her to just dock the phone, rather than docking then opening up the Dock Mode App from the phone.

Anyways, last few questions:

10kOhm triggers auto dock mode = That's the Car Mode App, right?

68kOhm triggers desk dock mode (also, a 47kOhm triggers desk dock mode) = And this is the Dock Mode App, right?

Have you tried syncing on PC while in Dock Mode?

Have you experienced any problem with the dock with the changes?

And also, have you tried connecting a MHL-HDMI and does it work? I heard/saw with an unmodified KiDiGi Charge & Sync Desktop Cradle, it works. You can check out what one member did here.

Thanks again man.

Click to expand...

Click to collapse

I don't have an MHL to try. Also did not try sync before going on holiday. No problems but I did go on vacation two days after I made the mod.

You are correct about the modes.

r2b2 said:

I've achieved the same thing with a few cheap NFC tags.
Stick it on the back of the dock and configure an NFC action against it and it's done.
I wouldn't trust myself with all of that hardware hacking either!

Click to expand...

Click to collapse

Please make a how-to post. I'd do another dock for the office with NFC.

Sorry for the delayed reply - I have been on holiday.

xSilv85 said:

damn, just realised I have the HDMI model xD
Can you tell me the wiring again?
It is in 2 pieces.. I guess black and white are ground and 5V to charge which. But the rest. How did you uncode them?

Click to expand...

Click to collapse

Yours is different. We should not guess at the color codes, this could lead to much sadness. But it is clear the hack has to be done at the end that plugs to the phone, it looks like the other end is only for power.

If you look at this pic: https://picasaweb.google.com/ModemJunki/OneXDockHack#5815365590917825778

You can see how I used a thin pin to pierce the SIDE of the wire (look at yellow wire too). The pin allowed me to trace the connections on the connector end to the wire with a multimeter set for continuity testing (beep!). It is VERY important not to try and pierce the center of the wire - they are so very thin that even a pin could break them.

Here is a picture of the dock (not on the phone) connector from the side you can see:
http://im.tech2.in.com/gallery/2012/jun/micro_usb_pinout_271738117322.jpg

xSilv85 said:

And the resistor values:
The manual does not correspond with pictures?
10kOhm vs 1kOhm?
6812 Ohm or 68 kOhm?

The type of resistor for at least 2,5W? Or is does the power not matter. I see on my dock 5V and 500 mA.

Click to expand...

Click to collapse

In this picture you see the values: https://picasaweb.google.com/ModemJunki/OneXDockHack#5815365606807034258

10kOhm and 6812kOhm. I used a 6812kOhm because it was what I had available for free - and it's a high-precision resistor. Normal resistor is I think +/- 5%, so mine is well within tolerances.

A 1/4 watt (0.25W) resistor is fine, also you can use a 1/6 watt (0.16W) because this is only for signaling, and the charging current will not flow through this. So as you say, the wattage does not matter for this application.

xSilv85 said:

I am confused sorry for being noob

Click to expand...

Click to collapse

I also am a noob, I don't know electronics theory and such, only enough to fix simple things like this.

r2b2 said:

Here's what I did:

* Buy a starter pack from RapidNFC (www.rapidnfc.com). These were the cheapest when I did this a while ago (I got "Starter Pack B")

* Download "NFC Task Launcher" from the Market (was £1.26 when I got it).

* Open the app and add an action to do what you want (in my case enable GPS, turn media volume down, launch Satnav program).
Once configured, select "Save & Write" and scan the NFC tag you want to use. If successful, when you put the phone near the tag it'll run the actions you selected.

If you can think of any other uses for the tags they can be programmed and put anywhere.

(I *think* this app doesn't actually write to the NFC tag, just records it's serial number. That means you can re-use the tags if you want by deleting the action and re-scannign the tag under another one)

Hope this helps.

Click to expand...

Click to collapse

Thanks!