How to make an HDA Dongle for Front Audio Support

Looking into it, it seems that there is special hardware required.

Pinouts;

http://www.intel.com/support/mothe [...] 015851.htm

Pin Signal Name Description
1 PORT 1L Analog Port 1 - left channel (Microphone)
2 GND Ground
3 PORT 1R Analog Port 1 - right channel (Microphone)
4 PRESENCE# Active low signal that signals BIOS that an Intel® HD Audio dongle is connected to the analog header. PRESENCE# = 0 when an Intel® HD Audio dongle is connected
5 PORT 2R Analog Port 2 - right channel (Headphone)
6 SENSE1_RETURN Jack detection return for front panel (JACK1)
7 SENSE_SEND Jack detection sense line from the Intel® HD Audio CODEC jack detection resistor network
8 KEY Connector key
9 PORT 2L Analog Port 2 - left channel (Headphone)
10 SENSE2_RETURN Jack detection return for front panel (JACK2)


For AC-97 Front Panel Audio
Pin Signal Name Description
1 MIC Front panel microphone input signal (biased when supporting stereo microphone)
2 AUD_GND Ground used by analog
3 MIC_BIAS Microphone power / additional MIC input for stereo microphone support
4 AUD_GND Ground used by analog audio circuits
5 FP_OUT_R Right channel audio signal to front panel (headphone drive capable)
6 FP_RETURN_R Right channel audio signal return from front panel (when headphones unplugged)
7 AUD_5V Filtered +5 V used by analog audio circuits
8 KEY No pin
9 FP_OUT_L Left channel audio signal to front panel (headphone drive capable)
10 FP_RETURN_L Left channel audio signal return from front panel (when headphones unplugged)

I think you're out of luck

I've come across this issue a number of times in searching for an proper HD solution.

Disabling front panel detection works for some folks with driver support, but I understand that some functionality is lost; specifically the speaker out isn't cutoff when the headphones are connected. I'd really like to build a solution for an existing case. The problem is in the document found at http://www.formfactors.org/develop [...] 4-005.pdf. The connectors for the front panel audio have changed internally.

In an AC97 panel shown on page 20 the connectors at Tip and Ring inside (the 1/8" TRS/stereo connector) are NC/Normally Closed and when a plug is inserted the circuit is interrupted. This disconnects/reroutes the audio to/from the device plugged in. With HD Audio there is a NO/Normally Open design; so when a plug is inserted the ring connector is pushed out and it closes another circuit so the signal at pin seven is connected to the sense1_return (pin 6) or sense2_return (pin 10) shown on page 25.

Wouldn't it be nice if we could mod our cases if we had the right 1/8" connectors and the inclination to mod the dongle board they are attached to? Wouldn't that be the right way? If only I could find the right connectors. That seems to be the hard part.

Just a thought. If anyone has had any luck with this I'd love to hear from you. Post to this thread and I'll be notified.

Thanks,
David

@wwwoholic

Thanks for the tip on the connectors. The 3566AN is perfect and would almost drop in. Cut a few traces and drill the extra holes out - jumper to the header pins and now it's HD instead of AC. Simple. Maybe 20 minutes of work.

I did pull out the dongle (board) and I guess Ultra, in their infinite wisdom, or to save $1.25 didn't implement the EMI circuitry specified in the 'AC97 spec which is the same in the HD Audio spec. It would take a fair amount of work (and parts hanging off the board) to do this so I hope things work out without. Maybe a daughterboard made from Radio Shack parts would work. Need 4 inductors (800 Ohms at 100Mhz) and 4 100pf caps.

Presence# detects if the dongle is attached. On page 80 of the ALC889 datasheet presence# is tied to +3.3V via a 10K resistor and GPI to South Bridge. The 1K resistor would probably be for current limiting to prevent damage to the South Bridge.

Instead of just a jumper between 2 & 4, put the resistor between 2 & 4 but wrap it in heatshrink tubing. A very small (1/8 watt or smaller if you can find it) would probably be fine. I'm glad you pointed that out.

Regards,
David

David,

what's interesting, is that I own several different Ultra boards and all of them except this one have EMI circuits. Well... I might just pull out the caps and inductors from one of those to save the trip to the store.

At 3.3V and 10K pull-up, we are talking about 30uA difference in current... nothing to worry about. Having said that I already put in 1K resistor in shrink wrap just as you suggesting. And my glued on micro switches work wonderful without any hassle of getting specialized jacks.

My overall conclusion is that about any AC97 dongle can be easily converted to true HD Audio. It's a wonder that thousands of hits on the web all point to useless threads ending up with "read the manual" or, in best cases, with "just plug AC connector and disable HD in BIOS" suggestions.

EDIT:

There might be an error in digikey description, since CUI product numbers generally contain diameter in them. SJ-635X series are 6.4 mm jacks and they do have isolated switches, like SJ-6356 for example.