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Hello Friedrich,
First of all, thank you very much for your reply.
It is wirth saying that in the "old" design there is an
additional similar LC circuit for connecting the ground signals from the
conenctor to the circuit ground. Should I also remove that?
BTW, what could then be the idea behind including such a circuit for the
SPORT interface? I don't see why such great manufacturers like
SpectrumSignal and Analog Devices could want to have an SPORT interface which
makes things really crappy. I think than more easily it is me who is wrong, than
they could be. I would like to know how to interface to such an LC filtered
circuit.
About the lines' length, I cannot control how long are they in
the EzLite. However, I could redesign my own daugtherboard to put the CODEC
as close as possible to the connector.
BTW, it is unavidable to use the connectors and the cable. Do you see any
other options I have for connecting external circuitry to the Old EzKit's
SPORT0? The newer design, at least, as an expansion interface... But the only
way to get SPORT available to the external world on the Old EzKit is by means of
the SPORT connector ...
I would like you explain more thoroughly about controlling the trace
impedance. Which values? Which configuration? The reasons why?
Again, if you can help me to find how to get such a cable, I will be really
grateful.
Regards,
JaaC
"Burgwedel, Friedrich"
<B...@askgroup.de> wrote:
Hi Jaime,
remove all of the LC filters from your board;
the newer design is right in
this point (compare the schematics to make
sure it is the only difference).
Next, keep the SPort lines as short as
possible (< 100 mm @ 22 Mhz; we use <
50 mm @ 11 Mhz!!); don't
use connectors if possible; and make sure that all
SPort lines match in
trace length. Finally, you may even need to control the
trace impedance on
the receiver's end by a resistor to GND or VCC. I do not
recommend a
series resistor in place of the LC filter since every such
resistor may
suppress ringing and overshot but will degrade slope.
Friedrich
-----Ursprgliche Nachricht-----
Von: Jaime Andres Aranguren
Cardona [mailto:j...@yahoo.com]
Gesendet: Dienstag, 10. Juni 2003 22:21
An: a...@yahoogroups.com
Betreff: [adsp] ADDU-21160-EZLITE SPORT
CableHello,
guys.
I need your help to find out how to get a cable for interfacing
the
ADDU-21160-EZLITE SPORT0 to external circuitry. Although in the manual
it
states that reference number DRFFC10X7RHU-RHU5, described as
"Straight-through assembly with locking connector on each end", distributed
by Gopher Electronics. I've searched, but haven't been able to find
it on
their website.
I bought the required connectors (AMP 2-487938-0)
and flexible film contacts
(AMP 487547-1) and some ribbon cable and built
the assembly myself, with
horrible results. I suspect it is because of
"uncontrolled" impedances,
which make the system not to couple well with
the EzKit.
Moreover, I need it to work with the old version of the kit, the
one
manufactured by SpectrumSignal, the one with the parallel port
interface.
With the newer ADDU-21160-EZLITE, the one with USB debugging
capabilities it
worked somehow good, but not flawlessly, due to the
imperfections of the
cable
I built. But with the old kit, it was impossible, the SPORT signals
degraded completely. It is notheworthy the fact that at the connector
inputs, the old kit has some kind of lowpass LC filtering, with 220pF
capacitance to gound and a ferrite EMI filter in series, whereas the newer
kit connected the SPORT signals directly from the AMPMODU System50
receptacle (AMP 104069-1) to the DSP SPORT pins.
And if you have any
special recomendations about to effectively interface to
the EzKit's
SPORT0, thank you very much. I mean, do I also need the LC
filter on my
system to get the system perfectly coupled? Is is that
sensitive? what
I'm trying to connect is a TLV320AIC23 Audio Codec, which I
suppose,
should match the SPORT pins characterisitcs withouth any special
circuitry.
Please, I look forward to having a response from you as soon
as possible.
So, I'd love you sent your replies to j...@sanjaac.com,
besides sending it
to the group.
Kindest
regards,
------------------------------
Jaime Andr Aranguren
Cardona
SanJaaC Electronics
www.sanjaac.com
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