[gta02-core] Audio ECN update

[Werner Almesberger]

Rene Harder wrote:
> I just uploaded the last missing audio ECNs (ecn0036-0038), which would
> need a brief discussion before implementation.

ECN00036: looks good to me. We have a lot of places to connect things
there already, don't need more.

ECN0037: looks good. Regarding your comment about the 2.5 mm audio
jack: unfortunately, there's no room for a 3.5 mm jack. Joachim once
made the very good point that the main use of the jack would be
people bringing their music collection to work so that they don't
have to upload to their company's PCs or such. So one could even
consider completely getting rid of the microphone path there,
removing one potential buzz victim and clearing the way for a capless
design.

ECN0038: 39pF+18pF ~= 56 pF ? Speaking of filters, building LC with
discrete components adds a lot of stuff. I did't realize you were
planning to use discrete bits, sorry. How about just using an
integrated filter ? We may need filters for SIM as well, and also
the UART to GPS looks like a filtering candidate to me. Not sure what
C4128 does.

> Also most audio ECN's are already implemented and need only the final
> review to get closed. Especially ecn0010, ecn0015 and ecn0031-0033.

I'll have a look at them in a bit.

> Still open is ecn0018 "Add beads/filters to audio signals
> leaving/entering can" which i think can be canceled because this is
> mostly taken care of in ecn0032.

Yes, agreed. Or move the EMI bit of ECN0032 to ECN0018, and make
ECN0032 ESD-only. Not that we were very consistent at avoiding
jumbo ECNs, e.g., "kill Glamo" :)

> Another ECN where we haven't decided yet what we are going to do is
> ecn0019  "Consider applying buzz fix", so comments are welcome.

I asked Joerg and he thinks it would be safer this way. He also
suggested to protect the headset mic as well. Not sure if we have
the space, though. This is already a very busy area.

Thanks !

- Werner