Hello every body,
i m working on dgtal ic tester , every thing is all right . The ic7400 nand gate attached with port 2 not showing good,port bit pin of port-2 not working as input & not taking o/p from gate 3 & 4 of 7400 .but port -1 bits(pin -4 & pin -6) is working as input. &taking o/p from nand gate o/p (gate-1 & gate-2).my logic to chek gates is attached.
Plz ........help ..........me........... Very much disturb
i have use 89c55.
Plz help me imideatly........as possible


thankyou
<snip>

 

It is always a good idea to post images to the forum using the advanced button.

Your schematic is very hard to make out because of the messy colored lines. If those are resistors between the microprocessor outputs and inputs and the IC under test, that might cause a problem. The colored lines make it hard to make them out.

A neater schematic and a statement of the operating algorithm would be very helpful. You code looks a bit too little to do thins like read the keyboard and perform a test.

 

Thanks for repply sir;
sorry but i m not getting your poit sir. My main problem is p2 is not working as o/p as we have assign it . Other hand p0 working as input & taking o/p from gate 1 & 2 from , where as o/p from gates 3 & 4 not is not accepting by p2, means not working as o/p.




Thanks allot sir.


Best regard
<shailesh agrahari>