Help required with 22V10 - Using a pin as Input an Output

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I'm having problems with the SDA part of an IIC implementation in a AMD 22V
10C (not from China!). I can Output data, to the SDA output, but I'm not ab
le to read the SDA input! My CUPL equations, as a whole, compile OK using W
INCUPL and the .JED file programs OK.

These are the intermediate declarations:


SCLL   =  FCD7 & !BnWR & !D6 ;  
SDAH  =  FCD7 & !BnWR &  D7 ;
SDAL   =  FCD7 & !BnWR & !D7 ;  

These are the outputs associated with SDA I/O:



/

* SDA I/O pin */

This is the equation for the SDA output control latch and sets the SDA outp
ut Low when needed. This sections works just fine.

rite FCD7 with D7=H */


 FCD7 with D7=0 */



This is the SDA output pin. Pulled high, externally, with a 4K7 resistor. W
orks as an output just fine.

 output required */

 output enabled */

This is the problem pin.

o D7 output on read of FCD7 */


If I toggle the SDAOE latch I can read its state through D7 e.g. I can read
 SDA output, however, if I set the SDAOE latch High, ready for  read of the
 SDA INPUT, I can't then read the input - I just read a High value on D7. I
t seems that the path from the SDA pin through to the & array isn't there!

Anybody have any clues to what's going wrong? Thanks . . . Dave H.

Re: Help required with 22V10 - Using a pin as Input an Output
 Dave Hitchins wrote:
-------------------------------------

Hi Dave,  

WTF makes you think your  is a  *basic*  question about  * electronics *  ?
?????????????  

You DID even read the NG name  ??  
-------------------------------------------------------



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2V10C (not from China!). I can Output data, to the SDA output, but I'm not  
able to read the SDA input! My CUPL equations, as a whole, compile OK using
 WINCUPL and the .JED file programs OK.  
Quoted text here. Click to load it
tput Low when needed. This sections works just fine.  
Quoted text here. Click to load it
 Works as an output just fine.  
Quoted text here. Click to load it
ad SDA output, however, if I set the SDAOE latch High, ready for read of th
e SDA INPUT, I can't then read the input - I just read a High value on D7.  
It seems that the path from the SDA pin through to the & array isn't there!
  
Quoted text here. Click to load it

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