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invert the DX-pin on McBSP ?

Started by olaf636 ●September 9, 2003
the voltage on the c6711-dx-pin was approx. 3,3v, changes to zero and
then starts the data-transfer.
but now on the c6713-dsk, it`s always zero, but the DR-pin of the
c6713-dsk`s is always 3,3v like the c6711, so when i connect these
pins, the voltage is approx. 1,7v with no changing during the
data-transfer.

does anybody know how i can change the dr- or dx-pin-voltage ?

can`t find any settings, "actice high/low" is only for the framing... sincerely,

olaf



Reply by Mike Dunn ●September 10, 20032003-09-10
Olaf,
 
Something is wrong! Do not leave those pins connected like that.  Your symptoms imply that one pin is "driving low" and the other pin is "driving high" - creating a voltage divider effect.  Double check your pins and config.
 
Which specific pins are you connected to??\
 
mikedunn

olaf636 <c...@t-online.de> wrote:
the voltage on the c6711-dx-pin was approx. 3,3v, changes to zero and
then starts the data-transfer.
but now on the c6713-dsk, it`s always zero, but the DR-pin of the
c6713-dsk`s is always 3,3v like the c6711, so when i connect these
pins, the voltage is approx. 1,7v with no changing during the
data-transfer.

does anybody know how i can change the dr- or dx-pin-voltage ?

can`t find any settings, "actice high/low" is only for the framing...sincerely,

olaf
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Reply by olaf636 ●September 10, 20032003-09-10
> Something is wrong! Do not leave those pins connected like that.
Your symptoms imply that one pin is "driving low" and the other pin is
"driving high" - creating a voltage divider effect. Double check your
pins and config.
>
> Which specific pins are you connected to??\
>
> mikedunn
 dear mike,

i have connected the DX0-pin from one dsk to the DR-pin from another dsk.
on the master-dsp is the DX-pin on 300mV and the DR-pin on 3,1V like
the slave-DR-pin.

but i believe that the McBSPs are not initialised correctly, so
perhabs they are still "connected" to the onboard AIC23-codec, because
when i write the code for the McBSP1 on the master-dsp i see nothing
on the scope....no clock, no frame, no data and DX/DR-pins are
low...no 300mV, just 0V......