Well excepting the same reaction as i have received before from all of you.

My project :-
" Designing an efficient town houses Secuirty System"

this involves controlling water motors , Lights, communication between houses and Guard rooms, using PIR etc...iam not asking for any hardware help as that will really be long to ask and long to reply and also i don't want to waste people time on my long questions as all are experts and have professional jobs to handle , all have their price for doing some work so some people may not reply me if i go in details of my project.

My project does not involve time critical issue like in case of clock or timer projects..

please just consider that:-

Devices which are connected with Port 2 sents a High Signal which means controller should do some specific task and when low is coming from any device controller should not do any thing to that device only.

Controller Atmel 89c51
Crsytal 11.05KOH

8 Devices..

should i firstly MOV P2,#00H so that P2 becomes logical low so that controller can respond to a High Signal?


e.g.
High on P2.0 means Water Motor should start.
Low means water motor stop.

High on P2.1 House Light should go ON and low mean Off

High on P2.2 means house bell should ring
low means stop ringing

High on P2.3 means Television should get ON and low means OFF.

(now the above is just an example and not the actual case)

using CJNE command for controller checking Port status and high coms at P2.0 , P2.1, P2.2 at the same time , is controller is scanning so fast that all three will be entertained or is there any chance of missing any?

Like controller should on a High signal to the following

P2.0 means Water Motor should start.
and to stop the motor controlle should wait for a low signal at P2.0

P2.1= House Light should go ON and wait for low

P2.2 = house bell should ring
and controller should wait for low.

but P2.3 , nothing should happen to TV on and off status since low is at P2.3

Now if one of the above device go sents low controller should be able to off that device not effecting any other..

what methodology should i apply...or using CJNE i should make large loops