Geek connector question

[Roy M. Silvernail]

I notice that the geek connector's pin 18 is labled "mixer input: s/pdif
(0-3.3V CMOS input)". Does this mean that I could take the coaxial digital
audio out from a DVD player, route it into this pin and have s/pdif come out
the optical output? If so, that is going to save me a coax->toslink
converter *and* an optical switch.

[seanadams]

Yes, but you will need a little circuitry to convert the 500mV signal
to 3.3V levels. Something like the "s/pdif coax input circuit" on this
page:

http://www.epanorama.net/documents/audio/spdif.html

Or you can just buy a s/pdif coax->fiber adaptor (which contains the
same circuit), remove the optical transmitter, and wire that signal
into the input.

Keep in mind this feature has not been tested. However, the pieces you
need are mostly already present in the server. Refer to the mas35x9
data sheet and mas35x9.pm.


On Dec 13, 2003, at 10:00 AM, Roy M. Silvernail wrote:

> I notice that the geek connector's pin 18 is labled "mixer input:
> s/pdif
> (0-3.3V CMOS input)". Does this mean that I could take the coaxial
> digital
> audio out from a DVD player, route it into this pin and have s/pdif
> come out
> the optical output? If so, that is going to save me a coax->toslink
> converter *and* an optical switch.
>

[Roy M. Silvernail]

On Mon, Dec 15, 2003 at 06:26:48AM -0800, Sean Adams wrote:
>
> Yes, but you will need a little circuitry to convert the 500mV signal
> to 3.3V levels. Something like the "s/pdif coax input circuit" on this
> page:

Thanks, Sean. One other question: Both that page and
http://www.andrewkilpatrick.org/mind/spdif/ make reference to +5V TTL.
Shouldn't that be +3.3V TTL for the squeeze? (as in, shouldn't I be
using 3.3V for the VCC on the inverter chip?)
--
Roy M. Silvernail is roy (AT) rant-central (DOT) com, and you're not
http://www.rant-central.com is the new scytale
Never Forget: It's Only 1's and 0's!
SpamAssassin->procmail->/dev/null->bliss

[seanadams]

That's correct, use the 3.3V supply. The 74HC04 part will operate
across a wide supply range (probably 2..6V). The circuit is the same
for 3.3V or 5V.


On Dec 15, 2003, at 7:34 AM, Roy M. Silvernail wrote:

> On Mon, Dec 15, 2003 at 06:26:48AM -0800, Sean Adams wrote:
>>
>> Yes, but you will need a little circuitry to convert the 500mV signal
>> to 3.3V levels. Something like the "s/pdif coax input circuit" on this
>> page:
>
> Thanks, Sean. One other question: Both that page and
> http://www.andrewkilpatrick.org/mind/spdif/ make reference to +5V TTL.
> Shouldn't that be +3.3V TTL for the squeeze? (as in, shouldn't I be
> using 3.3V for the VCC on the inverter chip?)
> --
> Roy M. Silvernail is roy (AT) rant-central (DOT) com, and you're not
> http://www.rant-central.com is the new scytale
> Never Forget: It's Only 1's and 0's!
> SpamAssassin->procmail->/dev/null->bliss
>

[Roy M. Silvernail]

On Mon, Dec 15, 2003 at 08:00:14AM -0800, Sean Adams wrote:
>
> That's correct, use the 3.3V supply. The 74HC04 part will operate
> across a wide supply range (probably 2..6V). The circuit is the same
> for 3.3V or 5V.

Gotcha. One last: where's the Mas35x9 datasheet? Doesn't show up in
the server docs and a Google search comes up empty.
--
Roy M. Silvernail is roy (AT) rant-central (DOT) com, and you're not
http://www.rant-central.com is the new scytale
Never Forget: It's Only 1's and 0's!
SpamAssassin->procmail->/dev/null->bliss