iPod Classic 6.5gen and 7gen In-Line Volume control

[Alan Tochterman]

Hello:

I am hoping that this is the correct forum to post my request.

The iPod Classic 120gb (6.5gen) and 160gb thin (7gen) were the only two models to support in-line volume control amongst a few others, for Apple or Apple approved earphones/headphones. 

The feature works with Apple's native operating system, but not on Rockbox. 

Since I am not a programmer, I have no idea how difficult it would be to enable this feature on these two devices.  But if it is possible, I would like to make the request.

Thank you

[saratoga]

Edit:  Misread as "line out" not "in line".

[Alan Tochterman]

Thank you for responding to my request, especially in a timely manner.

Perhaps I was not using the proper terminology.

I am referring to the volume control on headphones, not from the 30-pin connector.  iPods from the Video (5th generation) forward used a TRRS style headphone jack.  On the Video the extra contact point was for composite video out.  On the 6.5 and 7th generation iPods the extra contact point was for the volume control and microphone like on the iPhone 4S. 

On my Apple earphones and on my Bose QC20s there is a small control unit on the wire to the right ear peace which controls volume and pause, and I believe track forward and reverse.  When I am in Apple mode (which is almost never, these days) it works perfectly.

Once in Rockbox, it becomes non-functional. 

If I am taking a walk and my iPod is in my pocket, it is nice to be able to adjust the volume without having to take the iPod out.

adt

[saratoga]

Thats the headphone jack then. I don't know if anyone has looked at how to read data on that pin.

[Alan Tochterman]

I was unable to find anything in the forums nor on Reddit. 

Again, I have no clue how to make it operate.  I assume it is something in the logic board itself.  The 6th gens use the same earphone jack, as the Videos and the later units, but the feature is not on them.  So I assume it had to be in the board itself.

Is this forum the proper one to make requests ? 

[saratoga]

Assuming it hasn't been reverse engineered somewhere, you're going to have to wait for someone to take an interest in making that remote feature work. 

[insert.coin]

I'm sorry for necro-ing this thread, but I didn't think it was appropriate to start a new one. Please do let me know if this was the wrong decision.

The buttons on most [though not all, some Apple earbuds in particular act differently] wired headsets are just connected across the microphone and ground pins. The first button will just bridge the two. If you have more than one button, the secondary+ buttons also have an additional resistor to allow the device to distinguish between them. See Android's reference page: https://source.android.com/docs/core/interaction/accessories/headset/plug-headset-spec#electrical

As best as I can tell, the hardware IO required is already implemented on Rockbox on the iPod 6-7th gen. The microphone input does work - there is a recording app right on the homepage. If you plug in headphones with an in-line button, you can see the amplitude meter go to minimum when pressing and holding the inline button. I don't have earbuds with multiple buttons, but presumably they would act similarly (though to a different point on the meter).

This is at least a known standard and, if implemented, could mayhaps be applied to other players with microphone input?

[speachy]

This is at least a known standard and, if implemented, could mayhaps be applied to other players with microphone input?

This is (nearly?) always implemented using dedicated hardware, typically by the audio codec itself.

The problem with attempting to do this in software is that audio codecs (and controllers) in these players typically are one way -- ie you get recording _or_ playback, not both simultaneously.  The CS2L55 in the ipod6g is no exception.

[insert.coin]

Ah, very interesting! I'm way too used to phones where you could use the headset for calls.

I noticed on the freemyipod wiki the guess/assumption that the additionally populated section on the motherboard is for better headset support. I need to pull my device apart soon anyway, so I might take a closer look at that.