Re: when OR gates work as AND gates.!? NEEK

Altera_Forum · ‎12-05-2010

ok, I know its been a few years since I went to school but has someone redefined how OR gates work.!?

(See attached)

So I have two buttons on my NEEK connected to a OR2 gate. The output drives an led.

so problem is you have to press BOTH to get the led to come on.

I then tried swapping out the OR2 gate with an AND2 gate - guess what, either button lights the led.!?:confused:

Any comments welcome.

Thanks

Paul

Quartus 9.1 Build 222 Web Edition

WinXP SP2

Altera_Forum · ‎12-05-2010

Retry it with primitive AND, OR, instead of LPM_AND LPM_OR

Altera_Forum · ‎12-05-2010

Did you check the logic sense of your switches and LEDs??

Altera_Forum · ‎12-05-2010

Ha-ha-!! :D

Yes its the logic on the buttons and leds.

Buttons when pressed pull down and leds are pull down.

Thanks for pointing out the obvious - silly me!

Many thanks

Paul :)

Altera_Forum · ‎12-05-2010

Congratulations, you have just discovered de morgan's laws (http://en.wikipedia.org/wiki/de_morgan%27s_laws) the hard way!