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

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.

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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.

tput Low when needed. This sections works just fine.

Works as an output just fine.

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!