Applications Information (Continued)
SAMPLE PROGRAM FOR ADC0844 — INS8039 INTERFACE
CONVERTING TWO RATIOMETRIC, DIFFERENTIAL SIGNALS (Continued)
=
0054
0056
0057
0059
005A
32 53
81
JB1
LOOP
;IF INTR 1 GOTO LOOP
=
@
A, R1
MOVX
ORL
MOV
RET
;IF INTR 0 INPUT A/D DATA
89 01
A0
P1,&01H
;CLEAR THE A/D CHIP SELECT
;STORE THE A/D DATA
@
R0,A
83
;RETURN TO MAIN PROGRAM
I/O Interface to NSC800
DS005016-28
SAMPLE PROGRAM FOR ADC0848 — NSC800 INTERFACE
0008
000F
001F
3C00
NCONV
DEL
EQU
EQU
EQU
EQU
16
15
;DELAY 50 µsec CONVERSION
;THE BOARD ADDRESS
;START OF RAM FOR A/D
;DATA
CS
1FH
003CH
ADDTA
0000'
0004'
0008'
000A'
000C'
000F'
0012'
08 09 0A 0B
0C 0D 0E 0F
0E 1F
MUXDTA:
START:
DB
DB
LD
08H,09H,0AH,0BH
0CH,0DH,0EH,0FH
C,CS
;MUX DATA
06 16
LD
B,NCONV
21 0000'
11 003C
ED A3
LD
HL,MUXDTA
DE,ADDTA
LD
STCONV:
WAIT:
OUTI
;LOAD A/D’S MUX DATA
;AND START A CONVERSION
=
0014'
EB
EX
DE,HL
;HL RAM ADDRESS FOR THE
;A/D DATA
0015'
0017'
0018'
001B'
3E 0F
3D
LD
A,DEL
A
DEC
JP
;WAIT 50 µsec FOR THE
;CONVERSION TO FINISH
;STORE THE A/D’S DATA
;CONVERTED ALL INPUTS?
C2 0013'
ED A2
NZ,WAIT
INI
001D'
001E'
EB
EX
JP
DE,HL
C2 000E'
NZ,STCONV
;IF NOT GOTO STCONV
END
Note 14: This routine sequentially programs the MUX data latch in the signal-ended mode. For CH1-CH8 a conversion is started, then a 50 µs wait for the A/D to
complete a conversion and the data is stored at address ADDTA for CH1, ADDTA + 1 for CH2, etc.
17
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NSC [ National Semiconductor ]
