[DIY] "Car Dock" Cable - USB audio out + charging - UPDATED! (11-9-11)

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LGSilva

LGSilva

Senior Member
May 7, 2007
736
159
I just made my own "car dock" cable based on the information over the "Fun with resistors" thread.

Basically I have a cable with a micro-usb connector that switch my phone to "car dock" mode, audio via usb/aux and charging.

CHECK THE 2ND POST FOR UPDATES, PICTURES AND A QUICK VIDEO.​

WARNING:
  • This cable can physically damage/destroy your phone if made incorrectly.
  • If you don't have experience soldering electronics and small parts maybe you should not try this.
  • The usb cable will NOT work for sync/data - just charging.
  • I'm not responsible if you damage or destroy your phone/property and/or injury yourself or others.
  • Use this instructions at your own risk.
​
Parts that I used:


This is the pin-out for the usb connector:
usb_conn_pinout.jpg


Preparations:

1) Cut one of the aux cable connectors and expose the 3 wires:
  • Yellow = common ground
  • White = right channel
  • Red = left channel
The left/right channel may be inverted, test on your phone before you make the cable.

2) Cut the micro usb connector from the usb cable and expose the 4 wires:
  • Red = +5vcc
  • Black = ground
  • Green = not used
  • White = not used

Soldering:

Start with the audio cable:
  • Solder left channel wire to pin 2
  • Solder right channel wire to pin 3
  • Do NOT solder the ground wire yet

Now with the usb cable:
  • Solder red wire wire to pin 1
  • Do NOT solder the ground (black wire) yet

With the resistor:
  • Solder 1 resistor leg to pin 4
  • Solder the other resistor leg + audio ground (yellow wire) + usb ground (black wire) to pin 5

Almost done...
  • Test all the connections for short-circuit with a digital multimeter
  • Triple check for the right cable on the right place, you don't want to put that +5vcc on the wrong pin, it will fry your phone!
  • Just finish it with some epoxy glue to make sure the cables won't break where you soldered them and some shrink tube for a polished finish.
  • You must go to Settings > Dock Settings > Audio output mode and enable it to have the audio-out working.

I will post pictures next week when I will make a new cable with longer usb and better finish.
The cable I have now works fine, it's just ugly...


I hope this info will be useful for someone :D

Thanks to TheBeano for the info about the resistors :cool:
 
Last edited:
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LGSilva

LGSilva

Senior Member
May 7, 2007
736
159
* * U P D A T E * *
( a . k . a . v e r s i o n 2 . 0 )​

Hello all!
Thank you to all the people who rated this thread and enjoyed the info :D

After building my first cable from two different cables and finishing it up with some epoxy putty I started searching for a better and easier way to build this cable.

While searching on some Chinese accessories website I've found an iPhone USB/aux cable that would make this build easier and nicer.

This is the USB/aux cable from DealExtreme.com (item #34654):


From eBay I got this micro-usb connector with a "housing" (link):


The resistor is the same from the original post:


With this parts in hand I started by taking the iPhone connector apart:


With the soldering iron I removed the connector and with an blade I removed the cable "terminator"(?) so I could expose more wire and use my own "terminator"(?):


Using a multimeter and my "pro-mod" I was able to verify the cables and plugs.
All cables matched so I started soldering:


After checking for short-circuits and fixing the mistake I always make (I invert left and right channels) it was time to squeeze everything inside that tiny housing:


It looks nice but now let's test it:


Pictures are worth 1,000 words but a video is priceless (don't mind the music):
 
Last edited:
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CNLiberal

CNLiberal

Senior Member
Dec 8, 2008
421
50
Centennial, CO
Exactly What I Wanted

This is EXACTLY what I was looking for!! Once I see a picture/video of it in action, I'll get the parts. Question is, are you going to make your own car dock for it? Or are you going to purchase a generic dock? I'd like something that I can slide the phone into easily (and have the phone be horizontal). I am curious about the possibility of getting Digital Audio out instead of Analog. You seem to be the expert, do you think that's possible? Thanks!
 
E

Entropy512

Senior Recognized Developer
Aug 31, 2007
14,088
25,086
Owego, NY
I'm 95% certain digital audio out is not possible, except maybe for MHL/HDMI audio output via the MHL adapter.

There just aren't any provisions for it.
 
LGSilva

LGSilva

Senior Member
May 7, 2007
736
159
Thanks guys for the replies!

I got some PM about selling the cable. Right now I can't do it as I don't have enough time to make a good and durable cable.
The cable I have is kinda put together with epoxy putty and some shrink tubes.

Today I tested the cable and it works fine on my car.

I just found some iPod/iPhone cable that I think can make this build be easier and faster, basically you will change the apple connector for the micro-usb and add the resistor. I still waiting for the parts to arrive to test this new idea.

As Entropy512 said digital audio isn't possible with this setup but I will look in to it in the future to see if it's possible to use the mhl adaptor just for the audio.

Tomorrow I will post the pictures and a small video from it working with my current cable.

Thanks once again for the replies!
 
CNLiberal

CNLiberal

Senior Member
Dec 8, 2008
421
50
Centennial, CO
LGSilva said:
Thanks guys for the replies!

I got some PM about selling the cable. Right now I can't do it as I don't have enough time to make a good and durable cable.
The cable I have is kinda put together with epoxy putty and some shrink tubes.

Today I tested the cable and it works fine on my car.

I just found some iPod/iPhone cable that I think can make this build be easier and faster, basically you will change the apple connector for the micro-usb and add the resistor. I still waiting for the parts to arrive to test this new idea.

As Entropy512 said digital audio isn't possible with this setup but I will look in to it in the future to see if it's possible to use the mhl adaptor just for the audio.

Tomorrow I will post the pictures and a small video from it working with my current cable.

Thanks once again for the replies!
Click to expand...
Click to collapse

So digital audio out is not possible (that's kinda what I figured). But what about getting a USB->Digital Audio Out? I realize the kernel would have to support a device like this. I'm very new to the Android scene (less than a week). But I'd think that it would be possible. I can't post links yet, but it was a $25 USB->SPDIF device on Amazon. The reason I'm asking is that I'd like a way to eliminate the "road noise" (alternator noise) from my music.

And how are you controlling your music in your car? Do you have a remote for the phone? Bluetooth? Or are you doing it the "old fashioned way". LoL! Thanks again for your efforts!

Jim
 
F

foxbat121

Senior Member
Apr 27, 2006
2,846
256
CNLiberal said:
So digital audio out is not possible (that's kinda what I figured). But what about getting a USB->Digital Audio Out? I realize the kernel would have to support a device like this. I'm very new to the Android scene (less than a week). But I'd think that it would be possible. I can't post links yet, but it was a $25 USB->SPDIF device on Amazon. The reason I'm asking is that I'd like a way to eliminate the "road noise" (alternator noise) from my music.

And how are you controlling your music in your car? Do you have a remote for the phone? Bluetooth? Or are you doing it the "old fashioned way". LoL! Thanks again for your efforts!

Jim
Click to expand...
Click to collapse

You can use MHL->HDMI adapter then put in a HDMI->Digital audio converter to get the digital audio out without any modification to software. MonoPrice.com has both but I believe the later requires some external AC power.

I have an official Samsung car dock for my Captivate. After reading OP's post, I decided to mod that car dock. I stripe out the part that connects to Captivate USB port and contains microUSB socket for power and 3.5mm audio jack (it already has the required resisitor inside). Now all I need is some 5-wire microUSB male to female extension cable. This kind of cable is hard to come by but do exist.
 
Last edited:
CNLiberal

CNLiberal

Senior Member
Dec 8, 2008
421
50
Centennial, CO
I did some reading in the 'fun with resistors' thread, and while this mod looks to work, I'm worried about the lack of sufficient charging amperage. It seems that in order to do "high current charging" you need to short pins 4 and 5 on the micro USB plug. Well, those are in use by the audio output. This seems to be a _major_ design flaw in MHL. So basically, you'd have to turn off anything you don't need (WiFi primarily, maybe Bluetooth if you don't want integrated hands-free with your car's head-unit) in order to get an actual charge. So maybe this cable with a Tasker function to turn off those services and activate your Car Home app.

Please take what I say with a grain of salt. Again, I'm very new to Android and I'm probably wrong. :p
 
E

Entropy512

Senior Recognized Developer
Aug 31, 2007
14,088
25,086
Owego, NY
CNLiberal said:
I did some reading in the 'fun with resistors' thread, and while this mod looks to work, I'm worried about the lack of sufficient charging amperage. It seems that in order to do "high current charging" you need to short pins 4 and 5 on the micro USB plug. Well, those are in use by the audio output. This seems to be a _major_ design flaw in MHL. So basically, you'd have to turn off anything you don't need (WiFi primarily, maybe Bluetooth if you don't want integrated hands-free with your car's head-unit) in order to get an actual charge. So maybe this cable with a Tasker function to turn off those services and activate your Car Home app.

Please take what I say with a grain of salt. Again, I'm very new to Android and I'm probably wrong. :p
Click to expand...
Click to collapse

The device assumes that a proper high-current supply is present when a dock or MHL ID resistor is detected.

---------- Post added at 01:02 PM ---------- Previous post was at 01:01 PM ----------
CNLiberal said:
So digital audio out is not possible (that's kinda what I figured). But what about getting a USB->Digital Audio Out? I realize the kernel would have to support a device like this. I'm very new to the Android scene (less than a week). But I'd think that it would be possible. I can't post links yet, but it was a $25 USB->SPDIF device on Amazon. The reason I'm asking is that I'd like a way to eliminate the "road noise" (alternator noise) from my music.

And how are you controlling your music in your car? Do you have a remote for the phone? Bluetooth? Or are you doing it the "old fashioned way". LoL! Thanks again for your efforts!

Jim
Click to expand...
Click to collapse

In theory, I believe the device has USB Host/USB OTG support - but I know very little about enabling it. It MIGHT be possible to get USB sound cart to sort-of work - but getting the phone to route audio to the "new" interface would be extremely difficult.
 
LGSilva

LGSilva

Senior Member
May 7, 2007
736
159
The items that I've listed you can buy just 1.
They have other items where the minimum order is 5000.

Sent from my SAMSUNG-SGH-I777 using xda premium
 
E

Entropy512

Senior Recognized Developer
Aug 31, 2007
14,088
25,086
Owego, NY
Mouser is usually a bit better about minimum order quantity though - I think digikey improved over the years in that regard.

Usually Mouser has their quantity price breaks earlier.
 
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  • 22
    LGSilva
    LGSilva
    I just made my own "car dock" cable based on the information over the "Fun with resistors" thread.

    Basically I have a cable with a micro-usb connector that switch my phone to "car dock" mode, audio via usb/aux and charging.

    CHECK THE 2ND POST FOR UPDATES, PICTURES AND A QUICK VIDEO.    ​

    WARNING:
    • This cable can physically damage/destroy your phone if made incorrectly.
    • If you don't have experience soldering electronics and small parts maybe you should not try this.
    • The usb cable will NOT work for sync/data - just charging.
    • I'm not responsible if you damage or destroy your phone/property and/or injury yourself or others.
    • Use this instructions at your own risk.
    ​
    Parts that I used:


    This is the pin-out for the usb connector:
    usb_conn_pinout.jpg


    Preparations:

    1) Cut one of the aux cable connectors and expose the 3 wires:
    • Yellow = common ground
    • White = right channel
    • Red = left channel
    The left/right channel may be inverted, test on your phone before you make the cable.

    2) Cut the micro usb connector from the usb cable and expose the 4 wires:
    • Red = +5vcc
    • Black = ground
    • Green = not used
    • White = not used

    Soldering:

    Start with the audio cable:
    • Solder left channel wire to pin 2
    • Solder right channel wire to pin 3
    • Do NOT solder the ground wire yet

    Now with the usb cable:
    • Solder red wire wire to pin 1
    • Do NOT solder the ground (black wire) yet

    With the resistor:
    • Solder 1 resistor leg to pin 4
    • Solder the other resistor leg + audio ground (yellow wire) + usb ground (black wire) to pin 5

    Almost done...
    • Test all the connections for short-circuit with a digital multimeter
    • Triple check for the right cable on the right place, you don't want to put that +5vcc on the wrong pin, it will fry your phone!
    • Just finish it with some epoxy glue to make sure the cables won't break where you soldered them and some shrink tube for a polished finish.
    • You must go to Settings > Dock Settings > Audio output mode and enable it to have the audio-out working.

    I will post pictures next week when I will make a new cable with longer usb and better finish.
    The cable I have now works fine, it's just ugly...


    I hope this info will be useful for someone :D

    Thanks to TheBeano for the info about the resistors :cool:
    View
    16
    LGSilva
    LGSilva
    * * U P D A T E * *
    ( a . k . a . v e r s i o n 2 . 0 )    ​

    Hello all!
    Thank you to all the people who rated this thread and enjoyed the info :D

    After building my first cable from two different cables and finishing it up with some epoxy putty I started searching for a better and easier way to build this cable.

    While searching on some Chinese accessories website I've found an iPhone USB/aux cable that would make this build easier and nicer.

    This is the USB/aux cable from DealExtreme.com (item #34654):


    From eBay I got this micro-usb connector with a "housing" (link):


    The resistor is the same from the original post:


    With this parts in hand I started by taking the iPhone connector apart:


    With the soldering iron I removed the connector and with an blade I removed the cable "terminator"(?) so I could expose more wire and use my own "terminator"(?):


    Using a multimeter and my "pro-mod" I was able to verify the cables and plugs.
    All cables matched so I started soldering:


    After checking for short-circuits and fixing the mistake I always make (I invert left and right channels) it was time to squeeze everything inside that tiny housing:


    It looks nice but now let's test it:


    Pictures are worth 1,000 words but a video is priceless (don't mind the music):
    View
    2
    M
    masonsj
    Thank you & one suggestion.

    Thank you for your post & I made my own cable with your instruction.

    And, I modified your soldering as follows.

    Now with the usb cable:

    • Solder red wire wire to pin 1
    • Solder white wire to pin 2
    • Solder green wire to pin 3
    • Do NOT solder the ground (black wire) yet

    For Rapid Charging data+ & data- should be shorted and they are shorted in Rapid chargers.

    With your instruction Normal charging is possible, but Rapid charging is not.

    So I would like to suggest connect data cables like above or short 2 & 3 pin together.

    If pin 2 & 3 are shorted, your phone will think he is connected to Rapid charger (i.e. > 500mA).

    Thank you.
    View
    2
    CNLiberal
    CNLiberal
    CNLiberal said:
    So when I charge the phone at night, on it's normal charger and a long micro USB cable, will only pull the 500mA and not the full 750mA? That makes me feel better about the cable :) Thanks!
    Click to expand...
    Click to collapse

    Well, I finished my car audio dock cable last night. I tested all connections and everything seemed good. I plugged just the microUSB in (not on a charger at this point) and CM9 recognized Car Dock mode. That was encouraging. Here's a link to the pictures I took during the build. Some notes:

    Blue wire = Right Speaker
    Orange wire = Left Speaker
    Yellow Wire = Ground
    Red wire = USB +5V
    Black Wire = USB Ground

    I found it easier to solder the yellow/black/one leg of resistor together first, before attaching to the microUSB. I ruined one microUSB end by not doing this.

    On to testing:

    This morning, I plugged the phone in (at 96% charge) to my 1A cigarette lighter adapter, and fired up some locally stored (on SD card) music and Google Nav. I got to work (about 12 minutes later) and the phone was at 95%.

    So something is not right with this whole thing. I will say that I'm using CM9. They have not included car dock audio yet. That should be coming in the next nightly (hopefully, tonight). Either my cigarette lighter is not capable of putting out 1A, or, CM9 is missing something to tell the phone to charge at the full 750mA? Is that possible? Any ideas?
    View
    1
    R
    roundeye04092
    Note 3

    I tried one of the dealextreme samsung audio dock cables on my Note 3 (SM-900v), and got nothing, the resistor value they use is something like 358k. Made one with a 619k resistor as described in this thread, and bam! works perfectly! Fits in the compartment in my dash so much better than having 3/4" of headphone cable sticking out of the front.
    View

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