Car Dock Mode

[SupperDroid]

Anyone know what activates the home and car dock mode on the D3? I know on the X it i a magnet, I haven't been able to get a magnet to work.

 

[Fr33dom]

I cannot find any information on it but my suspicion is a small chip embedded in the dock that tells the phone what it is when powered up. I don't recall trying my phone in the dock without power though so I'll have to test that out.

 

[Fr33dom]

Without the dock powered, the phone just sits there. Once you power the dock, the phone switches to car mode. This pretty much argues for some sort of circuitry like a chip.

 

[SupperDroid]

Thanks for testing this, I had made a nifty car dock and home dock for my DX. Thought I could do the same for the D3 but doesn't look like it.

 

[leobg]

There are no magnets with D3. Indeed a circuit board resides inside the dock which tells the phone it is docked. It also allows the phone to distinct different home docks for example which is a neat feature. But it leaves home made dock out in the dry...

Sent from my DROID2 GLOBAL using Tapatalk

 

[REMilk]

The Droid 3 does NOT use magnet field recognition to identify when the phone is docked and into which dock it is placed. The secret is in the USB cable. The docking USB cables cannot be used for data access. Based on all that I have read, the data access pins within the micro USB are used to determine and identify which dock the Droid 3 is placed.

 

[SupperDroid]

Has anyone tried connecting the USB cable directly to the phone? ( if it is possible) and see if it will go into dock mode. If it does, then one should be able to figure the pin out.

 

[Fr33dom]

Just went down and pulled the cable from the dock and plugged it into the phone. Nothing happened. No charging, no nothing--nothing except the screen turned off after a few seconds. I then plugged the phone into the dock without the cable expecting what I had seen the last time--nothing--but instead, it went into car mode.

So I have to retract what I said earlier, but caution that someone should confirm these results. It isn't the cable, and it seems to be something passive--at least I don't think the d3 USB port provides power to external devices. That still does not rule out the earlier conclusions that some internal circuitry does the trick. It seems to rule out a small microchip which would need energy to activate it.

The most likely solution seems to me to be that the dock rewires its USB data lines in some fashion. The problem as I see it is that the Droid, not being a host, would rely on some mechanism such as the existence of power at the port to make it leap into some action. Perhaps I'm guessing too much here.

With respect to REMilk and leobg, I already knew from experience that it wasn't the magnets, but haven't found any technical details to prove my assumptions. I for one always like to see some measure of proof so If either of you have at least read or know of a source for information on this, well, I'm curious.

 

[SupperDroid]

Nice work, we are getting closer. If you look between the USB and the HDMI port you can see some sort of sensor, I am thinking this is what sets it off. Perhaps it is some kind of optical sensor. Maybe placing a piece of black tape over this sensor and docking it may reveal something. I am sorry I do not have a dock to test but I am very interested in solving this.

 

[evilashell]

I have taken the car dock apart and after u plug the micro usb into the car dock it goes through a small circuit board I assume this tells the phone it is in a dock.

Sent from my DROID3 using DroidForums

 

[SupperDroid]

Then the circuit board must be powered by the phone since it works without the cable as Fr33dom mentioned.

 

[Fr33dom]

Nice work, we are getting closer. If you look between the USB and the HDMI port you can see some sort of sensor, I am thinking this is what sets it off. Perhaps it is some kind of optical sensor. Maybe placing a piece of black tape over this sensor and docking it may reveal something. I am sorry I do not have a dock to test but I am very interested in solving this.

I think what you are referring to here is the dead battery LED. which illuminates when there is so little power left in the battery that it cannot power the display to show you that its charging.

 

[Fr33dom]

Then the circuit board must be powered by the phone since it works without the cable as Fr33dom mentioned.

Actually, I said I didn't think it could do that.

A microchip would need so small a charge to fire off a signal that perhaps a small capacitor/battery exists to send a signal to the phone to ID the dock. That would explain why when I first plugged the phone into the dock, it didn't respond. The dock hadn't been powered for a couple days since I'm on vacation. I'm still going to cling to the theory of a microchip until otherwise informed, but that doesn't necessarily rule out what has been posited before about something being done over the data lines--which, by the way, has some cred since the dock apparently cannot be used to transmit data. I'll confirm this for myself a little later today. I just like the microchip idea better, but then I only know enough about electrical engineering to get into trouble.

Oh, and since I mentioned vacation, here is a series of shots using my d3 and Hugin to stitch them all together:

View attachment 41043

 

[REMilk]

Based on the following information, I still believe that the Docking for the Droid 3 is based on electrical reading from the pins of the micro USB connector on the docks. This is why I think it is in this manner.

1. You cannot transfer data when the Droid 3 is docked in either the car dock or the multimedia dock. This is straight from Verizon and I think I saw it on the Multimedia Dock instructions or box. (This shows that at least 1 of the 2 data lines in the USB cable are used for something other than data).

2. The person who modified an OG Droid multimedia dock to use for the Droid 3 used the OG Droid short cable and is able to transfer data to/from his Droid in this dock. His Droid 3 does not recognize that it is docked in this modified OG Droid dock. This also shows that the pin definition is redefined within the short cable.

#1 shows me that the short cables in both the Droid 3's car and multimedia docs are each using one of the two data signal pins, in a proprietary manner, to identify when the Droid 3 is dock and which dock it is in.
#2 demonstrates that this proprietary redefinition/usage of the data lines occurs in the short cable within the dock since any micro-USB cable that meets Motorola specification can be used with the Droid 3 AC charging, auto charging, data transfer/charging, or docking. There are cables that do not meet the Motorola specification, such as those used by the LG ENV3, and some third-party. I have a bunch of these that do not have same pin definition for data, they charge fine the Droid 3 fine, but cannot be used for data transfer.

I have not yet been able to obtain a Droid 3 multimedia dock or short cable that I can take apart and verify the connections.

Just my opinion, most likely your will differ.
Bob

Bob

 

[leobg]

Have a look at these pics for more insight.