This is my first assembler project and I have come accross a problem that I cannot seem to figure out. My program takes 3 analog inputs from a tri-axial accelerometer and inputs them to a aduc812 that does an a to d conversion then serials the seperate channels out through the Txd pin. The problem I am having is that I am using a variable called first that is set to 1 at the begging of the program to tell if it is the first time through the program loop. In the middle of the progarm I set first to 0 before it checks the analog input a second time so that the progarm knows that it is not the first time through the loop. The only problem is that the program does set first to 1 but for some reason it is not changeing first to 0 when I redifine it later in the progarm. The program assembled fine and when I single step through it everything else works, but it dose not redifine first to 0. The aduc812 has an 8052 compatible core and I am using the $mod52 control at the beggining of the program and the variable first is initialized to 1 before the progarm starts its loop to read the analog inputs. Why is first not being redifined to 0? Can someone give me any suggestions please.
Here is a code example:
$mod52
;VARIABLE DECLARATIONS
Chx DATA 030H ;x channel stored in address 30 hex
. (DECLARATION OF OTHER VARIABLES)
.
.
First SET 1 ; flag for first time through loop
; START PROGRAM
org 00h
. (SET REGISTERS FOR A/D CONVERSION ETC.)
.
Loop:
if (first)
mov Tchx,Chx
mov Tchy,Chy
mov Tchz,Chz
endif
First SET 0
;CALCULATE CHECKSUM
;SET SERIAL PORT FOR TRANSMISSION OF DATA
;OUTPUT DATA
;BACK TO BEGGING OF LOOP