So i'm doing a technical thesis project which controls dampers of a HVAC unit according to the amount of people inside a building.. I have a circuit designed that will increment when a person enters a building and decrement when someone leaves. This is where my trouble is. These voltages go into a comparator and latch circuit which outputs a number to an 8255 PPI Interface card. The program should then output in order to move a motor on one way or the other to open or close a damper. I have very little skills in assembly language programming and just know the bare basics. Any help on this program would be greatly appretiated. This is what I have so far..

A100
MOV AL,90
MOV DX,303
OUT DX,AL

 

Hi you need to atleast give a rough diagram showing the lines(address,data and the signals) of the PPI and the up that way one could help. Which up are you using anyways?Also the OUT instruction is a 2 byte instruction while you seem to have used 3 bytes!

Also first you need to initialize the device for e.g port setting interrrupt enable/disable....

 

Little change in plans. I think I may now actually use a PIC instead of the 8255 PPI because the PIC can accept an analog input which makes life a lil easier for me. Although the same problem persists with the programming. Not exactly sure how or where to start with the code.

 

Which PIC are you talking about? the 8259a? or using PIc microcontrollers and changing everything altogather? Also PIC and PPI are two different things. One is a parallel data transfer device and the other is an interrupt controller.