Is it possible to write s/w for h/w testing?
Can we also find out exact fault location?
now ADC is placed after analog circuit, so we can check ADC o/p, but how to check analog o/p(adc i/p) ?

Also for display(7-seg LED MUX) checking, we can illuminate each segment of particular digit and check wheather theres any short connection with other digit/segment or not?
(all similar segments of all digits are grouped together, but other than that if theres any short ? that is to be checked )

Memory check can be done by writting random data at random location and reading back from same location.

Keypad check can also be done by displaying pressed key.

I'm using ADC: TLC 7135, how to check it ?
and how to find out fault at analog side from it?
or if we need to check OPAMP(thru s/w) , what can be done?

Theres no scope available at working site, and normally thats the case.
The whole objective is to save/minimize manual testing time. And test circuit using s/w. Ofcourse we need to make some assumptions like controller is working !!
( We will need to check all power supplies and microcontroller manually. )

Do write back your comments, suggestions/approach and resourses.

Best regards,
Neil