[gta02-core] Audio ECN review

[Rene Harder]

Great, thanks for the review.

Werner Almesberger wrote:
> I think ECN0032 and ECN0033 are close to being ready to move to
> "Execute". A few few small correction:
>
> - ECN0033: should it be C3008 instead of C3006 in
>   | - C3007 and C3008 (GSM modem input)
>   ? (C3008 bypasses VDD.)
>   
Done.

> - ECN0033: In addition to the part name (CM105X5R105M16AT)
>   I'd also specify the parameters, i.e., X5R, 1 uF, 20%, 16 V, 0603.
>   
I removed the part number completely and added only the specific
parameters.
>   Actually, perhaps we should switch all the 1 uF caps to 0402 and
>   use something like the C1005X5R0J1 (X5R 1.0 uF, 10%, 6.3 V, 0402).
>
>   Since we need more 1 uF parts than we'll get from Openmoko, it's
>   actually cheaper and simpler to buy a reel that has the right
>   quantity.
>   

I've added a new section todo with 2 possible capacitors, both should be
easy to source.

> - ECN0032: line ends are CRLF, tsk, tsk :)
>   
=-O , fixed!

> - ECN0032: the varistors "same as D4402" are also something we need
>   to replace, 1) for the reason above, and 2) the specific part
>   Openmoko used (Karmax KEV040209151A) is difficult to get in the West.
>
>   The characteristics are: 9 Vdc, 6.5 Vac, 150 pF. We could use the
>   Littlefuse V9MLA0402NR (120 pF) or V9MLA0402LNR (33 pF) instead.
>
>   There aren't a lot of choices in the 0402 form factor, so I don't
>   have a second source at Digi-Key.
>   
I don't think they are critical, if we can't find components with the
correct value we can use the next higher ones (e.g. with 10VAC) instead.
Here is another one, which fits perfectly VRS0402KR090500N - VARISTOR,
0402, 50PF, 9VDC (Farnell)