[Q] Car Mode Cable

ShadowDrake · Apr 9, 2014

So not sure I'm going to have any luck with this but it's worth asking - maybe someone has done the same thing.

I tried to follow the following thread to make a cable that will start the phone into car mode:

http://xdaforums.com/showthread.php?t=1475272

I have a working OTG cable and a USB A-A. When I connect the cable to a charger and plug it into the phone I just get a notification that says "The USB host cable is plugged in. Unable to charge the device"

So I did a little more looking and people said to trigger car mode pins 4 and 5 must be connected. I hacked up a cable and jumped them together. Plugging in the hacked up cable gives the same notification - "The USB host cable is plugged in. Unable to charge the device"

So apparently my OTG cable is working as intended but doesn't launch car mode.

Does anyone know what the M7 uses to detect the car dock? I don't want the stock HTC car dock since it goes on the windshield and I want it clipped into a vent.

Edit: Looks like this may be in the source somewhere...

http://xdaforums.com/showthread.php?t=820275

Anyone familiar with the kernel source able to help? I'm going to do my own searching but I'm hardly familiar with linux.

Edit 2: Found values for HTC One X. Just don't have resistors handy:
10kOhm triggers auto dock mode
68kOhm triggers desk dock mode (also, a 47kOhm triggers desk dock mode)

mcerk02 · Apr 10, 2014

ShadowDrake said:
So not sure I'm going to have any luck with this but it's worth asking - maybe someone has done the same thing.

I tried to follow the following thread to make a cable that will start the phone into car mode:

http://xdaforums.com/showthread.php?t=1475272

I have a working OTG cable and a USB A-A. When I connect the cable to a charger and plug it into the phone I just get a notification that says "The USB host cable is plugged in. Unable to charge the device"

So I did a little more looking and people said to trigger car mode pins 4 and 5 must be connected. I hacked up a cable and jumped them together. Plugging in the hacked up cable gives the same notification - "The USB host cable is plugged in. Unable to charge the device"

So apparently my OTG cable is working as intended but doesn't launch car mode.

Does anyone know what the M7 uses to detect the car dock? I don't want the stock HTC car dock since it goes on the windshield and I want it clipped into a vent.

Edit: Looks like this may be in the source somewhere...

http://xdaforums.com/showthread.php?t=820275

Anyone familiar with the kernel source able to help? I'm going to do my own searching but I'm hardly familiar with linux.

Edit 2: Found values for HTC One X. Just don't have resistors handy:
10kOhm triggers auto dock mode
68kOhm triggers desk dock mode (also, a 47kOhm triggers desk dock mode)

I never had a desire to put my phone into car mode and maybe I am not sure what you are trying to accomplish, but couldn't you just use an app like trigger to program an NFC tag and place it on your car dock so when your phone is placed in the dock and touched the tag, BOOM, phone is in car mode.....then just touch the tag again when exiting car to exit car mode?

ShadowDrake · Apr 11, 2014

mcerk02 said:
I never had a desire to put my phone into car mode and maybe I am not sure what you are trying to accomplish, but couldn't you just use an app like trigger to program an NFC tag and place it on your car dock so when your phone is placed in the dock and touched the tag, BOOM, phone is in car mode.....then just touch the tag again when exiting car to exit car mode?

That's what I'm leaning towards doing if this all fails. It would just be nice to use what I've already bought - and sliding the phone into the dock would automatically trigger this mode once it was plugged in and charging. An NFC tag would accomplish the same thing maybe.

Car dock mode will be nice since it'll toggle bluetooth on for me and start playing music automatically. It's in a nice location in the car for viewing and could be used as GPS without having to dig it out of my pocket.

ShadowDrake · May 26, 2014

Bumping a reply up to this since I finally got around to putting some more time into this project...

10k ohm resistor puts the phone right into car dock mode and takes it out of car dock mode when unplugged. Exactly what I was looking for. 47-68k ohm likely triggers desk dock mode so I'll save that one for another day.

Just going to cut up a USB cable and throw the resistor between the two target pins and I'll have a working car dock cable. Happy hunting all.

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[Q] Car Mode Cable

ShadowDrake

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mcerk02

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ShadowDrake

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ShadowDrake

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