Make my own Type C to Type C+3.5mm adapter?

[DocSwag]

So it's a sad day to realize that my next phone probably won't have a headphone jack.

 

This isn't a dealbreaker for me, as I don't use headphones that often. But I think it's still going to be annoying at times, with the biggest annoyance being I can't charge and use headphones at the same time. And it's looking like the only working type c to type c+3.5 mm jack adapter is gonna cost $45. Screw that, I'm not buying that.

 

So I was thinking; theoretically shouldn't it be possible for me to make my own?

If you look at this diagram, all the VBUS pins aren't being used by the type c to 3.5mm jack adapter. However, the VCONN ones are. But theoretically, it may be possible to get around this?

 

I was wondering about you guys' thoughts on this.

[mariushm]

i would say it depends on the phone and the charger, maybe the charger has some chip inside which talks to the phone through the usb data lines allowing the phone to control the charge voltage and the maximum current (in a sort of quickcharge 2.0 or 3.0 way)

 

Having the audio directly on usb pins seems to me like more of a hack, probably something supported only by your phone or some manufacturer? I don't know... Normally you could have a usb dac chip or a sound card more or less and the phone would send the digital data through the usb port and you'd have sound from the sound chip.

 

[.spider.]

5 hours ago, mariushm said:

 

Having the audio directly on usb pins seems to me like more of a hack, probably something supported only by your phone or some manufacturer?

It is an official USB-C feature which is not supported by all devices.

 

https://e2e.ti.com/blogs_/b/analogwire/archive/2016/07/07/usb-type-c-why-mobile-phone-designers-should-remove-the-audio-jacks-from-our-phones

[DocSwag]

8 hours ago, mariushm said:

i would say it depends on the phone and the charger, maybe the charger has some chip inside which talks to the phone through the usb data lines allowing the phone to control the charge voltage and the maximum current (in a sort of quickcharge 2.0 or 3.0 way)

 

Having the audio directly on usb pins seems to me like more of a hack, probably something supported only by your phone or some manufacturer? I don't know... Normally you could have a usb dac chip or a sound card more or less and the phone would send the digital data through the usb port and you'd have sound from the sound chip.

 

 

3 hours ago, .spider. said:

It is an official USB-C feature which is not supported by all devices.

 

https://e2e.ti.com/blogs_/b/analogwire/archive/2016/07/07/usb-type-c-why-mobile-phone-designers-should-remove-the-audio-jacks-from-our-phones

It looks to me like the VCONN/CC pins are really just being used by the phone to detect that there is a device there. If you look, the actual data is being sent over the Dp, Dn, and SPU pins, whereas the VCONN/CC pins are attached to a switch that connects to ground.

 

After reading this more closely, I think it is possible without much fancy circuitry just with charging speed limited to 5v @ 500mA. The CC and VCONN stuff only seems to be used by the charger if you're using USB 3.0/3.1 charging; 1.1 and 2.0 don't require it but you're limited to 500 mA.

 

I think I'll try this out, as I'm not sure how you could get more than 500 mA without some more fancy circuitry. Thanks guys!

 

What I might experiment with is trying to connect the 3.5mm jack only as data and not to the CC/VCONN pins, and see if that works...

[Ralms]

On 11/5/2017 at 2:42 PM, DocSwag said:

 

It looks to me like the VCONN/CC pins are really just being used by the phone to detect that there is a device there. If you look, the actual data is being sent over the Dp, Dn, and SPU pins, whereas the VCONN/CC pins are attached to a switch that connects to ground.

 

After reading this more closely, I think it is possible without much fancy circuitry just with charging speed limited to 5v @ 500mA. The CC and VCONN stuff only seems to be used by the charger if you're using USB 3.0/3.1 charging; 1.1 and 2.0 don't require it but you're limited to 500 mA.

 

I think I'll try this out, as I'm not sure how you could get more than 500 mA without some more fancy circuitry. Thanks guys!

 

What I might experiment with is trying to connect the 3.5mm jack only as data and not to the CC/VCONN pins, and see if that works...

Since on the headphones Type-C plug the SBU1 and SBU2 seem to connect to ground when headphones are connected, I would even say that it would charge full speed at 2Amps because on the charger Type-C receptacle the matching pins for SBU1 and SBU2 seem to be CC1 and CC2 that are connected to ground too.