[alsa-devel] Audigy bay protocol

[Takashi Iwai]

At Thu, 26 Jun 2008 14:11:55 +0100,
Tony "Chainsaw" Vroon wrote:
> 
> Good afternoon,
> 
> Having spent some time looking at the MIDI that the internal/external
> Audigy bays emit, I noticed that they report more then is currently used
> by the LIRC driver.
> 
> There is one thing missing in here, which is how to control the bay
> power LED (which is supposed to blink when the card is muted) and the
> CMSS LED. I am not sure whether this is controlled through MIDI SysEx
> sequences or through other means.
> 
> Due to an annoying hardware failure in my Audigy 4 Pro I can not
> continue this endeavour, but I want to share what I have.

Thanks.  It's a useful information.

> Based on this, perhaps one can extend the EMU10K1/2 driver a bit with
> headphone muting and volume control through the bay. With thanks to the
> libdouze author, Arnaud de Bossoreille de Ribou.
> 
> Midi System Exclusive ( extended manufacturer id == 0x2021 )
> Payload for 61 bay message:
> 61 00 01 00 XX YY
> 
> XX 
> 00 = button push event
> 01 = volume knob event
> 02 = jack sense event
> 
> For XX=00 button push:
> Bit 1: CMSS
> Bit 2: Mute
> 
> For XX=01 volume knob:
> Bit 1: Always set
> Bit 7: Set for downward adjustment, unset for upward adjustment
> 
> For XX=02 jack sense:
> YY contains jacks
> Bit 1: headphone
> Bit 2: digital out (back of bay)
> 
> Response to initialization:
> Midi System Exclusive ( extended manufacturer id == 0x2021, payload == |
> 60 00 02 03 | )       <-- Unknown, bay version?
> Midi System Exclusive ( extended manufacturer id == 0x2021, payload == |
> 61 00 01 00 02 01 | ) <-- Jack sense update
> 
> I hope it is of use to someone.

Do you mean that after sending the last two SYSEX, the device returns
the SYSEX messages above appropriately?  In which timing?

So far, the driver doesn't care about the contents of in/out MIDI
bytes but just receives/sends as is.  Supporting this in the kernel
driver would need a bit more work than normal jack / volume knob
sensing in other drivers.


thanks,

Takashi