Nick SayerNote that to get the output to work, you have to set the TX source to "AIF" - that is, you have to configure the chip to generate the TX output from the i2s input on the chip. You can do this in amixer by using cset to set the "Tx Source" control to whichever value (probably 1) that decodes to "AIF". The default is "S/PDIF RX", which means that it comes from the receive input, but that will only work if the i2s clocks happen to match up with the S/PDIF received signal.
If you don't do this, then playing audio won't light up the output receptacle (which means it just won't work).
You don't need to do this for recording - it always sends the S/PDIF receiver input to the i2s receive pin. But you must insure that the parameters for the reception actually match up with the input source.
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Do those lines go in the config.txt file? Thanks
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No, they're command line commands.
Note (for the next person) that you may need to use a "-c n" argument (n is the card number) to specify the WM8804 interface. You can list the interfaces with "aplay -l".
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Sorry I wasn't more specific, but at the moment I am out of town and away from my available RPis.
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Thank you, the concrete command I needed was
```
# amixer controls
numid=1,iface=MIXER,name='Tx Source'
# amixer cset numid=1 'AIF'
numid=1,iface=MIXER,name='Tx Source'
; type=ENUMERATED,access=rw------,values=1,items=2
; Item #0 'S/PDIF RX'
; Item #1 'AIF'
: values=1
```
that did it (sorry, took me some time to figure this out as I now nothing about the raspberry/linux audio subsystem)
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Hi Nick, I received the HAT today but cannot get it to work. `amixer` returns
```
Simple mixer control 'Tx Source',0
Capabilities: enum
Items: 'S/PDIF RX' 'AIF'
Item0: 'S/PDIF RX'
```
and if I do `amixer cset numid=1 1` nothing happens and the transmitter light does not go on. I assume I need a different command to get it going? Can you help me?
Thanks!
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